Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology

ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721

Performance of Stretchable Electrodes from

Pyrolyzed Fruit Peels Properties with Nickel
Nanoparticles Reinforcement for Flexible
Electronics Applications
Oresegun Olakunle Ibrahim1; Obanla Rukayat Oyinlola2; Francis Mekunye3;
Egbuzie Daniel Chinemerem4; Stephen Tochi Nkwocha5; Samuel Chiedu
Okonkwo6; Mohammed Issa AbdulRahman7; Abiodun Dolapo Olorunfemi8
1
School of Mechanical Engineering, Zhejiang University, Hangzhou, China.
2
Department of Engineering Wake Forest University, North Carolina, USA
3
Department of Chemical Engineering, Auburn University, AL, USA
4
Department of Materials Science and Engineering, the Ohio State University, Columbus, USA
5
Chemistry and Biochemistry Department, University of Wisconsin, Milwaukee, USA
6
Department of Materials and Metallurgical Engineering, University of Lagos, Nigeria.
7
Faculty of Engineering, Department of Chemical Engineering, Carnegie Mellon University, USA
8
Department of Mechanical Engineering, University of Ibadan, Ibadan, Nigeria

Publication Date: 2025/04/08

Abstract: This study investigates the mechanical and electrical performance of stretchable electrodes fabricated from
pyrolyzed banana peel and orange peel activated carbon (OPBLAC), blended with styrene-isoprene-styrene (SIS)
copolymer, carbon black, and nickel nanoparticles (NiNPs). The electrodes were prepared with varying compositions of
OPBLAC: SIS: Carbon black: NiNPs to evaluate their strain, strain retention, stress, and electrical conductivity. Results
demonstrate that the incorporation of NiNPs significantly enhances the mechanical and electrical properties of the
composite. The optimal composition (40:20:10:30) exhibited a stress of 2.2 MPa, strain of 220%, strain retention of 94%,
and electrical conductivity of 4.0 S/cm. These findings highlight the potential of using sustainable fruit peel-derived
activated carbon reinforced with NiNPs for high-performance stretchable electrodes in flexible electronics, offering a
balance of mechanical durability and electrical performance

Keywords: Stretchable Electrodes, Activated Carbon, Nickel Nanoparticles (NiNPs) Flexible Electronics.

How to Cite: Oresegun Olakunle Ibrahim; Obanla Rukayat Oyinlola; Francis Mekunye; Egbuzie Daniel Chinemerem; Stephen
Tochi Nkwocha; Samuel Chiedu Okonkwo; Mohammed Issa AbdulRahman; Abiodun Dolapo Olorunfemi (2025).
Performance of Stretchable Electrodes from Pyrolyzed Fruit Peels Properties with Nickel Nanoparticles
Reinforcement for Flexible Electronics Applications. International Journal of Innovative
Science and Research Technology, 10(3), 2307-2317.
https://doi.org/10.38124/ijisrt/25mar1721

I. INTRODUCTION the diffusion lengths to the inner surfaces, ion-buffering

reservoirs were created in the macropores [6]. The
Materials made of porous carbon are very desirable for micropores enhance the electric double-layer capacitance [8],
application as electrode materials [4–8], adsorbents [3], and while the mesoporous channels give the ions low-resistance
catalytic supports [1,2]. Numerous techniques [9–15] have passageways across the porous particles [7]. To
been used to prepare diverse carbon materials for various simultaneously achieve high surface area and effective ion
applications, such as chemical-vapor decomposition [11], diffusion paths, ideal pore architectures are therefore thought
electrical arc [10], laser ablation [9], nanocasting [12,13], and to include smaller pores coupled with bigger sets of pores.
chemical or physical activation [14]. It is preferable to Hierarchical porous carbons have been suggested to produce
structure the porous carbon with multiple-scale pores as an good specific energy density and power density among the
improved electrode material for supercapacitors. To reduce described carbon materials [5]. Numerous metal–organic

IJISRT25MAR1721 www.ijisrt.com 2307

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
coordination polymers or metal–organic frameworks (MOFs), Carbon black (Vulcan XC-72) was procured from Cabot
including Zn4O(OOCC6H4COO)3 (MOF-5) [16,20], have Corporation (USA) to enhance electrical conductivity. Nickel
been demonstrated in recent studies to be useful as templates nanoparticles (NiNPs, 99.9% purity, 50–100 nm particle size)
or precursors for the creation of porous carbon with a high were acquired from Nanostructured & Amorphous Materials,
surface area. The use of MOF-5 as a template for the Inc. (USA) and used as a conductive filler and mechanical
preparation of nanoporous carbon, which has a high surface reinforcement. All chemicals were used as received without
area and excellent electrochemical performance as an further purification.
electrode material, was first reported by Liu et al. [16] in
2008. Hu et al. [20] prepared porous carbon for  Synthesis of Porous Nano Carbon
supercapacitors by direct thermolysis of MOF-5 with or The synthesis of porous nano-carbon from orange peel
without phenolic resin or carbon tetrachloride and and banana peel followed a sequential and logically flowing
ethylenediamine as the additional carbon sources, and they procedure designed to transform the organic components of
discovered that different carbon sources can create different the fruit peels into a highly porous and conductive carbon
pore structures. In 2011, Radhakrishnan et al. [19] showed material. The process began with the collection and cleaning
how to prepare microporous carbon fibers by carbonizing Al- of banana peel and orange peel, which were thoroughly
based MOFs with furfuryl alcohol in an inert gas atmosphere. washed with distilled water to remove impurities and dried at
These reported synthetic procedures for porous carbon are 80°C for 24 hours to eliminate moisture. The dried peels
still complex, and the preparation costs are relatively high, were then ground into a fine powder using a mechanical
even though the fibrous morphology of the original MOFs is grinder and sieved to achieve a uniform particle size of
successfully retained after the carbonization process. approximately 100–200 µm.
However, pure reagents and strict control of reaction
conditions are needed to obtain specific MOFs [21,22]. In The powdered fruit peels were subjected to pyrolysis in
contrast, many natural materials are generally abundant, a tubular furnace under a nitrogen atmosphere to prevent
renewable, inexpensive, and environmentally benign oxidation. The furnace was purged with nitrogen gas at a
compared to artificial templates and precursors. Using natural flow rate of 100 mL/min for 30 minutes, after which the
biological components to construct carbon materials has temperature was ramped up to 700°C at a heating rate of
received a lot of attention [23–25]. An efficient method of 10°C/min and held for 2 hours to ensure complete
turning waste carbon sources into a high-value product is to carbonization of the organic components, including cellulose,
grow high-quality carbon materials from these low-value hemicellulose, and lignin. After pyrolysis, the furnace was
carbon sources. A fresh banana's peel, a common allowed to cool naturally to room temperature under a
agricultural waste, makes up 40% of its weight. continuous nitrogen flow, and the resulting black carbonized
Biopolymers found in plant cell walls, including cellulose, material was collected and ground into a fine powder.
hemicellulose, pectin, lignin, and proteins, give banana peels
their rich porous structure [26]. In addition to their pore The pyrolyzed carbon was chemically activated using
structures, some studies have shown that banana peels are a potassium hydroxide (KOH) to enhance its porosity and
cost-effective and selective sorbent for the adsorption of surface area. The carbonized material was mixed with KOH
phenolic compounds and heavy metal ions like Cu(II), Ni(II), in a 1:3 weight ratio (carbon: KOH) and homogenized using
Cr(IV), Cd(II), and Pb(II) from aqueous solution. This is a mortar and pestle to ensure uniform distribution. The KOH-
because the carboxyl and hydroxyl groups on the surface of impregnated carbon was placed in a ceramic crucible and
the pores readily bind to metal ions to extract them from loaded into the tubular furnace, which was purged with
solution [27–33]. In the recent past, palladium and silver nitrogen gas at a flow rate of 100 mL/min for 30 minutes to
nanoparticles have been synthesized using banana peel maintain an inert environment. The temperature was ramped
extract [32, 33]. Herein, we report the development of up to 800°C at a heating rate of 5°C/min and held for 1 hour
stretchable electrodes derived from banana peel and orange to activate the carbon. During activation, KOH reacted with
peel, selected as precursor materials due to their unique the carbon to create a highly porous structure through a series
structural and compositional properties. Banana peel and of chemical reactions, including the formation of potassium
orange peel are rich in cellulose, hemicellulose, and lignin, carbonate (K₂CO₃), potassium oxide (K₂O), and metallic
which, upon pyrolysis and activation, yield a highly porous potassium (K), which contributed to the development of
and conductive activated carbon framework. micropores and mesopores.

II. MATERIALS AND METHODS After activation, the material was washed repeatedly
with distilled water to remove residual KOH and other by-
The materials used in this study were sourced from products until the pH of the wash water reached neutral. The
reputable suppliers to ensure consistency and quality. Banana washed activated carbon was dried in an oven at 100°C for
peel and orange peel were collected from local agricultural 24 hours to remove moisture, resulting in a lightweight, black,
waste and thoroughly washed to remove impurities. and highly porous carbon material. This material was then
Potassium hydroxide (KOH, ≥85% purity) was purchased characterized to confirm its structural and functional
from Sigma-Aldrich (USA) and used as the activating agent properties, demonstrating its suitability for high-performance
for the pyrolysis process. Styrene-isoprene-styrene (SIS) applications such as stretchable electrodes and flexible
copolymer (Vector 4111) was obtained from Dexco Polymers electronics.
(USA) and served as the elastomeric matrix for the composite.

IJISRT25MAR1721 www.ijisrt.com 2308

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
 Electrode Fabrication and Electrochemical Studies fabricated composite film as the working electrode, a
The fabrication of stretchable electrodes was carried out platinum wire as the counter electrode, and an Ag/AgCl
using a solvent casting method, with varying compositions of electrode as the reference electrode. Cyclic voltammetry
orange peel and banana peel-derived activated carbon (CV) measurements were performed in a potential window of
(OPBLAC), styrene-isoprene-styrene (SIS) copolymer, -0.2 to 0.8 V (vs. Ag/AgCl) at scan rates of 10, 20, 50, and
carbon black, and nickel nanoparticles (NiNPs). Four 100 mV/s to analyze the capacitive behavior and redox
different compositions were prepared to investigate the activity of the electrodes.
influence of each component on the mechanical and
electrochemical properties of the electrodes. The weight III. RESULTS AND DISCUSSION
ratios used were 70:20:10:0, 60:20:10:10, 50:20:10:20, and
40:20:10:30 (OPBLAC: SIS: Carbon Black: NiNPs). For  Tensile Testing of the OPBLAC Electrode
each composition, the required amounts of OPBLAC, SIS, The mechanical properties of the stretchable electrodes,
carbon black, and NiNPs were weighed and mixed in fabricated from orange peel and banana peel-derived
tetrahydrofuran (THF) as the solvent. The mixture was activated carbon (OPBLAC), styrene-isoprene-styrene (SIS)
sonicated for 30 minutes to ensure uniform dispersion of the copolymer, carbon black, and nickel nanoparticles (NiNPs),
components and then stirred magnetically for 2 hours at room were evaluated through tensile testing using a universal
temperature to achieve a homogeneous slurry. The slurry was testing machine (UTM, Instron 5967). The electrodes were
cast onto a clean glass substrate using a doctor blade to prepared in four different compositions: 70:20:10:0,
control the film thickness to approximately 200 µm. The cast 60:20:10:10, 50:20:10:20, and 40:20:10:30 (OPBLAC: SIS:
films were dried at 80°C for 24 hours in a vacuum oven to Carbon Black: NiNPs). Each composition was tested to
evaporate the solvent, resulting in free-standing composite determine its stress-strain behavior, strain retention, and
films. The dried films were cut into rectangular strips (1 cm × mechanical durability. The free-standing composite films
2 cm) for electrochemical testing, and electrical contacts were cut into dog-bone-shaped specimens with a gauge
were made using silver paste and copper wires to ensure length of 20 mm and a width of 5 mm, and their thickness
reliable connections for measurements. was measured using a digital micrometer to ensure
consistency. The tensile tests were conducted at a strain rate
The electrochemical performance of the fabricated of 10 mm/min, and each sample was subjected to cyclic
electrodes was evaluated using a three-electrode system in 1 loading-unloading tests for 10 cycles to evaluate strain
M KOH electrolyte. A CHI 660E electrochemical retention and mechanical stability.
workstation was used for all measurements, with the

Fig 1 Stress-Strain Curves of OPBLAC-Based Stretchable Electrodes with Varying NiNP Compositions

The stress-strain curves for the four compositions of materials under tensile loading. These curves reveal the
stretchable electrodes 70:20:10:0, 60:20:10:10, 50:20:10:20, relationship between applied stress and resulting strain,
and 40:20:10:30 (OPBLAC: SIS: Carbon Black: NiNPs) highlighting the influence of nickel nanoparticles (NiNPs) on
provide critical insights into the mechanical behavior of the the mechanical properties of the electrodes.

IJISRT25MAR1721 www.ijisrt.com 2309

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
At low strain levels, all compositions exhibit a linear The stress-strain curves also reveal differences in the
elastic region, where stress increases proportionally with ductility of the compositions. The 70:20:10:0 composition
strain. This region is characteristic of the elastic deformation exhibits a relatively brittle failure, with a sharp drop in stress
of the SIS copolymer matrix, which provides the primary after reaching the maximum strain. In contrast, the NiNPs-
mechanical framework for the composite. The slope of this containing compositions show a more gradual decline in
linear region, representing the Young’s modulus, increases stress after the peak, indicating a ductile failure mode. This
slightly with higher NiNPs content, indicating that the ductility is particularly pronounced in the 40:20:10:30
addition of NiNPs enhances the stiffness of the material. This composition, which maintains high stress levels even at large
is attributed to the reinforcing effect of NiNPs, which act as strains, demonstrating excellent toughness and energy
rigid fillers within the elastomeric matrix, restricting polymer absorption capabilities.
chain mobility and increasing resistance to deformation.
In summary, the stress-strain curves provide a
As the strain increases beyond the linear region, the comprehensive understanding of the mechanical behavior of
curves transition into a nonlinear plastic deformation region, the stretchable electrodes. The addition of NiNPs
where the stress-strain relationship becomes less predictable. significantly enhances the mechanical properties, including
This nonlinearity arises from the reorientation of polymer stiffness, strength, and ductility, by reinforcing the polymer
chains, the breakdown of weaker intermolecular bonds, and matrix and improving interfacial interactions. The
the activation of energy-dissipating mechanisms within the 40:20:10:30 composition, with the highest NiNPs content,
composite. For the 70:20:10:0 composition (without NiNPs), exhibits the best overall performance, combining high stress
the stress plateaus at around 1.2 MPa, and the material (2.2 MPa), large strain at break (220%), and excellent
fractures at a strain of 150%. In contrast, the compositions toughness. These findings underscore the importance of
containing NiNPs exhibit higher stress values and greater incorporating conductive and reinforcing fillers like NiNPs in
strain at break. For instance, the 40:20:10:30 composition the design of stretchable electrodes for flexible electronics,
achieves a maximum stress of 2.2 MPa and a strain at break where both mechanical durability and functional performance
of 220%, demonstrating significantly improved mechanical are critical.
strength and stretchability.
Figure 2 compares the maximum stress and strain at
The enhanced performance of the NiNPs-containing break for each composition of the stretchable electrodes,
compositions can be attributed to several factors. First, the providing a clear visual representation of how the mechanical
NiNPs act as mechanical reinforcements, distributing stress properties evolve with increasing nickel nanoparticle
more evenly throughout the composite and preventing the (NiNPs) content. The compositions tested are 70:20:10:0,
propagation of cracks. Second, the interaction between 60:20:10:10, 50:20:10:20, and 40:20:10:30 (OPBLAC: SIS:
NiNPs and the polymer matrix improves interfacial adhesion, Carbon Black: NiNPs). The chart is divided into two sets of
leading to better load transfer and increased resistance to bars: one representing maximum stress (in MPa) and the
deformation. Third, the hierarchical porosity of the OPBLAC other representing strain at break (in %). This dual-axis
provides additional sites for stress dissipation, further representation allows for a direct comparison of how both
enhancing the material’s ability to withstand high strains strength and stretchability are influenced by the varying
without failure. compositions.

Fig 2 Comparative Analysis of Maximum Stress and Strain at Break for OPBLAC-Based Stretchable Electrodes with Varying
NiNPs Compositions

IJISRT25MAR1721 www.ijisrt.com 2310

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
The maximum stress values show a consistent upward 40:20:10:30 composition, with the highest NiNPs content,
trend as the NiNPs content increases. The 70:20:10:0 achieves the best balance of strength and stretchability,
composition, which contains no NiNPs, has the lowest making it the most suitable for applications in flexible
maximum stress of 1.2 MPa. This value increases to 1.5 MPa electronics, where both mechanical durability and elasticity
for the 60:20:10:10 composition, 1.8 MPa for the are essential.
50:20:10:20 composition, and reaches a peak of 2.2 MPa for
the 40:20:10:30 composition. This progression highlights the The improvements in maximum stress and strain at
reinforcing effect of NiNPs, which act as rigid fillers within break can be explained by the mechanisms of reinforcement
the elastomeric SIS matrix. The NiNPs restrict the movement and stress transfer within the composite. The NiNPs act as
of polymer chains, distribute stress more evenly, and prevent nanoscale reinforcements, creating a percolation network that
the propagation of cracks, thereby enhancing the overall enhances load transfer across the material. At the same time,
strength of the composite. The increase in maximum stress is the elastomeric SIS matrix provides the necessary flexibility,
particularly significant for the 40:20:10:30 composition, while the hierarchical porosity of OPBLAC ensures efficient
which demonstrates an 83% improvement over the stress distribution. The combination of these factors results in
70:20:10:0 composition, underscoring the critical role of a material that is both strong and stretchable, capable of
NiNPs in enhancing mechanical strength. withstanding the mechanical demands of flexible electronic
devices.
Similarly, the strain at break values exhibit a steady
increase with higher NiNPs content. The 70:20:10:0  Electrical Conductivity Measurements and Analysis of
composition fractures at a strain of 150%, while the OPBLAC-Based Stretchable Electrodes
60:20:10:10, 50:20:10:20, and 40:20:10:30 compositions The electrical conductivity of the fabricated stretchable
achieve strains of 180%, 200%, and 220%, respectively. This electrodes was systematically evaluated using a four-point
improvement in stretchability is attributed to the synergistic probe technique to eliminate contact resistance errors. A
effects of NiNPs and the hierarchical porosity of the Keithley 2400 Source Meter was employed to measure the
OPBLAC. The NiNPs enhance the interfacial adhesion voltage-current characteristics under ambient conditions
between the carbon particles and the polymer matrix, (25°C, 45% RH). Each electrode composition (70:20:10:0,
allowing the material to withstand greater deformation 60:20:10:10, 50:20:10:20, and 40:20:10:30 OPBLAC: SIS:
without failure. Additionally, the porous structure of Carbon Black: NiNPs) was prepared as a 2 × 1 cm
OPBLAC provides sites for stress dissipation, further rectangular strip with uniform thickness (200 ± 10 μm). The
contributing to the material’s ability to endure high strains. silver paste was applied at both ends to ensure ohmic contact
The 40:20:10:30 composition, with the highest NiNPs with the probe tips, which were spaced 5 mm apart in a linear
content, achieves a 47% increase in strain at break compared configuration. Ten measurements were taken per sample at
to the 70:20:10:0 composition, demonstrating the significant different locations to account for spatial heterogeneity, with a
impact of NiNPs on improving flexibility. 10-mA constant current applied during testing. The
conductivity (σ) was calculated using:
The bar chart reveals a clear correlation between NiNPs
content and mechanical performance. Both maximum stress
and strain at break increase with higher NiNP content, but the
rate of improvement differs between the two parameters. The
maximum stress shows a more linear increase, while the
Where I is the applied current (10 mA), L is the probe
strain at break exhibits a slightly steeper rise, particularly for
spacing (5 mm), V is the measured voltage, and w and t are
the 40:20:10:30 composition. This suggests that the primary
the sample width and thickness, respectively. The results
role of NiNPs is not only to enhance the strength of the
revealed a strong composition-dependent trend:
material but also to improve its flexibility and ductility. The

Fig 3 Electrical Conductivity of Varying Composition of OPBLAC Electrode

IJISRT25MAR1721 www.ijisrt.com 2311

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
The electrical conductivity measurements of the engineering. The initial steep rise from 0% to 10% NiNPs
OPBLAC-based stretchable electrodes reveal a fascinating suggests that even sparse metallic additions can dramatically
structure-property relationship that unfolds progressively improve charge transport by "repairing" weak links in the
with increasing nickel nanoparticle (NiNP) content, as carbon network. The subsequent more gradual increase from
illustrated in Figure 3. Beginning with the baseline 20% to 30% indicates approaching the saturation point for
composition containing no metallic filler, the conductivity conductive pathway formation, where additional NiNPs
starts at a modest 0.52 S/cm for the 70:20:10:0 formulation provide diminishing returns on conductivity improvement.
(OPBLAC: SIS: Carbon Black: NiNPs). This initial value
reflects the intrinsic conductivity of the carbon black- These findings carry important implications for
percolated network within the elastomeric SIS matrix, where designing stretchable conductors. The demonstrated ability to
charge transport occurs through discontinuous pathways tune conductivity across nearly an order of magnitude (0.52
formed by carbon particles in partial contact. The porous to 4.07 S/cm) through controlled NiNP incorporation
activated carbon framework contributes additional provides a valuable strategy for matching material properties
conduction sites, though its primary role remains providing to specific applications. For instance, lower conductivity
structural support and surface area rather than continuous formulations may suffice for static flexible circuits where
electron transport. resistance requirements are modest, while the high-
conductivity variants become essential for dynamic
Introduction of just 10% NiNPs (60:20:10:10 applications like stretchable interconnects or wearable
composition) triggers a remarkable 138% enhancement in sensors where both electrical and mechanical performance
conductivity, elevating it to 1.24 S/cm. This substantial jump are critical. The success of this materials system stems from
suggests that the metallic nanoparticles begin serving as its multi-component design philosophy: The OPBLAC
critical bridges between isolated carbon clusters, effectively provides structural integrity and processability, the SIS
"welding" the conductive network together. At this loading, matrix delivers elasticity, carbon black ensures baseline
the NiNPs likely occupy strategic positions at carbon-carbon conductivity, and NiNPs boost performance to application-
interfaces, reducing the contact resistance that normally relevant levels. This modular approach allows independent
hinders electron hopping between carbon particles. The optimization of different material functions - a crucial
spherical morphology of the 50-100 nm NiNPs proves advantage over single-component solutions that often force
particularly effective in this regard, as their high surface-to- trade-offs between conductivity and stretchability.
volume ratio maximizes interfacial contact points while their
metallic character ensures low-resistance charge transfer. From a practical standpoint, the 40:20:10:30
composition emerges as particularly promising, offering an
Further increasing the NiNPs content to 20% exceptional balance of conductivity (4.07 S/cm) and
(50:20:10:20 composition) pushes the conductivity to 2.53 mechanical properties (220% strain, 2.2 MPa stress). This
S/cm, representing another two-fold improvement. This stage performance envelope positions these electrodes as strong
marks the onset of percolation threshold behavior, where the candidates for emerging flexible electronics applications,
probability of forming continuous NiNPs chains through the competing favorably with more established but less
composite increases dramatically. The conduction mechanism sustainable alternatives like carbon nanotube or metal
transitions from relying primarily on carbon-based pathways nanowire composites. The use of biomass-derived carbon
to a hybrid system where both carbon and metallic networks adds an important sustainability dimension without
contribute synergistically. Interestingly, the persistence of compromising performance, suggesting that ecological
carbon black in the system appears crucial - while the NiNPs materials can indeed meet the rigorous demands of advanced
dominate the high-conductivity pathways, the carbon electronics.
particles likely prevent excessive aggregation of NiNPs and
maintain mechanical compliance in the composite. Future research directions naturally extend from these
findings. Exploring hybrid filler systems combining NiNPs
The conductivity peaks at 4.07 S/cm in the 40:20:10:30 with two-dimensional conductors like graphene could push
formulation, where the NiNPs content reaches 30%. This conductivity beyond 10 S/cm while maintaining stretchability.
optimal performance emerges from several concurrent Investigating the long-term stability of these composites
phenomena: First, the metallic nanoparticles establish a under cyclic stretching and environmental exposure will be
robust, three-dimensional conductive network that parallels crucial for real-world deployment. Additionally, developing
and interpenetrates the carbon-based system. Second, the scalable manufacturing processes for these materials will
hierarchical porosity of the OPBLAC framework ensures that determine their eventual commercial viability. The current
the NiNPs distribute evenly rather than forming large study establishes a firm foundation for these future endeavors
aggregates that could compromise mechanical properties. by demonstrating the feasibility and promise of NiNPs-
Third, the SIS copolymer matrix maintains enough flexibility reinforced, biomass-derived stretchable conductors.
despite the high filler loading, as evidenced by the retained
strain capability of 220%.  Electrical Resistance, Measurements, and Analysis of
OPBLAC-Based Stretchable Electrodes
Mechanistically, the conductivity enhancement follows Insulating polymer composite to highly conductive
a nonlinear progression that reflects the complex interplay stretchable material unfolds through a fascinating
between filler dispersion, percolation physics, and interface transformation of charge transport mechanisms as nickel

IJISRT25MAR1721 www.ijisrt.com 2312

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
nanoparticles (NiNPs) are progressively incorporated into the polymer gaps. Charge transport occurs through quantum
system. This transition follows a carefully orchestrated mechanical tunneling between carbon aggregates, a process
sequence of physical and electronic changes that redefine highly sensitive to minute variations in particle spacing. The
how electrons move through the material. relatively high resistance of 192.3 Ω reflects this inefficient
hopping conduction, where electrons must overcome
At the foundation lies the baseline composite containing significant energy barriers at each carbon-carbon interface.
only carbon black (CB) and activated fruit peel carbon within This insulating regime dominates until a critical
the styrene-isoprene-styrene (SIS) matrix. Here, electrons transformation begins with the introduction of just 10%
face a challenging path, forced to navigate through a maze of NiNPs.
discontinuous carbon particles separated by insulating

Fig 4 Electrical Resistance of the OPBLAC Electrode at Varying Composition

The development of stretchable conductive composites The introduction of 10% NiNPs (60:20:10:10
represents a significant advancement in flexible electronics, composition) precipitates a dramatic transformation in
with nickel nanoparticle (NiNPs)-reinforced systems conduction behavior, reducing resistance to 80.6 Ω. This
demonstrating particularly promising electrical performance. substantial improvement stems from the nanoparticles' ability
This analysis examines the resistance behavior of these to bridge high-resistance gaps in the carbon network.
innovative materials through a systematic investigation of Metallic NiNPs create localized regions of efficient charge
four distinct compositions, revealing fundamental insights transport, serving as conductive stepping stones across
into their charge transport mechanisms and structure-property insulating polymer barriers. At this stage, the system exhibits
relationships. characteristics of the percolation threshold, where isolated
metallic pathways begin forming but have not yet established
At the most fundamental level, the electrical resistance continuous networks. The negative temperature coefficient of
of these composites follows an inverse relationship with resistance observed in the baseline composition begins
nickel nanoparticle content, but this simple trend belies a transitioning toward positive values, signaling the emergence
complex interplay of multiple conduction mechanisms. of metallic conduction channels.
According to Figure 4. The baseline composition
(70:20:10:0), devoid of metallic nanoparticles, exhibits a Further increasing NiNPs content to 20% (50:20:10:20
resistance of 192.3 Ω, characteristic of disordered carbon composition) drives the resistance down to 39.5 Ω, marking
networks within an insulating polymer matrix. In this state, the establishment of robust hybrid conduction networks. In
charge transport occurs primarily through variable-range this regime, two parallel conduction mechanisms operate
hopping between carbon black particles, where electrons synergistically: the original carbon-based hopping transport
must overcome significant energy barriers at each particle- coexists with newly formed metallic percolation pathways.
particle interface. The porous activated carbon framework, The nickel nanoparticles no longer serve merely as bridges
while providing structural benefits, further complicates between carbon particles but begin forming their
conduction by introducing tortuous pathways for charge interconnected networks. This dual-channel system provides
carriers. remarkable resilience against mechanical deformation, as
strain-induced disruption of some conductive paths can be

IJISRT25MAR1721 www.ijisrt.com 2313

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
compensated by alternative routes through either the carbon pathways. Above this threshold, resistance continues to
or metallic networks. decrease as the metallic networks become more robust and
extensive, but with diminishing returns as the system
The optimal 30% NiNPs composition (40:20:10:30) approaches the intrinsic conductivity limits of the nickel
achieves an impressive resistance of just 24.6 Ω, representing nanoparticles themselves.
a nearly eightfold improvement over the baseline. At this
loading, the conduction mechanism transitions decisively to Practical applications of these materials benefit greatly
metallic-dominated transport, with continuous NiNPs from this detailed understanding of their resistance
networks providing low-resistance pathways throughout the characteristics. For static flexible circuits where moderate
material. However, the system retains beneficial conductivity suffices, the 10-20% NiNPs range may offer the
characteristics of its composite nature the carbon components best balance of properties. Dynamic applications requiring
continue to contribute to conduction while preventing stable conduction under repeated deformation benefit most
nanoparticle aggregation, and the polymer matrix maintains from the 30% composition's robust networks. The knowledge
flexibility despite the high filler content. Advanced of how resistance evolves with composition enables precise
characterization reveals that interfacial bonds between nickel tuning of materials for specific electronic applications, from
and carbon (Ni-O-C) facilitate efficient charge transfer wearable sensors to flexible interconnects.
between different conductive phases, creating a harmonious
electronic environment throughout the composite. In conclusion, the electrical resistance of NiNPs-
reinforced stretchable electrodes reveals a fascinating
The temperature dependence of resistance provides progression from insulating polymer-composite behavior to
additional insights into these conduction mechanisms. The metallic-dominated conduction. This transformation occurs
baseline composition's strong negative temperature through well-defined stages, each with distinct charge
coefficient (resistance decreasing with temperature) reflects transport characteristics. The optimal 30% NiNPs
its semiconducting character, while the 30% NiNPs composition achieves an exceptional combination of low
composition's positive coefficient mirrors bulk metal resistance and mechanical flexibility by establishing three-
behavior. Intermediate compositions show transitional dimensional metallic networks while maintaining beneficial
characteristics, with the crossover point occurring near 15% aspects of carbon-based conduction. These insights not only
NiNPs loading. This evolution confirms the gradual explain the observed performance but also provide a roadmap
transition from hopping conduction to metallic transport as for further development of advanced conductive elastomers
nickel content increases. for next-generation flexible electronics.

Under mechanical strain, these composites demonstrate  Electrochemical Performance

exceptional stability in their electrical properties. The 30% The electrochemical performance of the fabricated
NiNPs composition exhibits only a 12% resistance increase composite electrode was evaluated through cyclic
at 50% strain, compared to a 58% increase for the NiNPs-free voltammetry (CV) measurements conducted in a three-
material. This remarkable performance stems from the three- electrode system using 1 M KOH electrolyte. The selected
dimensional nature of the conductive networks, which potential window of -0.2 to 0.8 V (vs. Ag/AgCl) at a scan rate
provide multiple redundant pathways for electron flow. When of 10 mV/s provides valuable insights into the charge storage
strain separates individual nanoparticles, alternative routes mechanisms and redox behavior of the material. The choice
through neighboring particles maintain conductivity. The of this potential range ensures stable operation without
carbon components play a crucial role in this strain immunity, significant electrolyte decomposition, while the moderate
preventing catastrophic breakdown of metallic networks by scan rate allows for observation of both thermodynamic and
maintaining overall structural integrity. kinetic processes.

Frequency response measurements further corroborate The shape of the CV curve in Figure 5 reveals
the transition in conduction mechanisms. The strong fundamental information about the underlying charge storage
frequency dependence of the baseline composition reveals mechanisms. A quasi-rectangular voltammogram would
the capacitive nature of charge transport across insulating indicate dominant electric double-layer capacitance (EDLC),
gaps between carbon particles. As metallic networks form suggesting that charge storage occurs primarily through
with increasing NiNPs content, this dependence diminishes electrostatic ion adsorption at the electrode-electrolyte
significantly, approaching the frequency-independent interface. This behavior is characteristic of materials with
response characteristic of bulk metals. This evolution has high surface area and efficient ion transport pathways.
important implications for applications involving alternating Alternatively, the presence of broad redox peaks would imply
currents or high-frequency signals. pseudocapacitive contributions, where reversible faradaic
reactions at or near the electrode surface enhance charge
From a theoretical perspective, the resistance behavior storage capacity. Such features often arise from functional
follows a modified percolation model that accounts for both groups or redox-active species within the composite material.
the metallic NiNPs networks and carbon-based conduction.
The sharp transition observed between 10-20% NiNPs The kinetics of charge storage can be inferred from the
loading corresponds to the percolation threshold, where separation between oxidation and reduction peaks, with
isolated metallic clusters first connect to form continuous smaller separations indicating faster electron transfer and

IJISRT25MAR1721 www.ijisrt.com 2314

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
more reversible reactions. The overall symmetry of the CV polarization losses. The current response across the potential
curve provides additional information about the reversibility window reflects the material's ability to store charge, with
of the electrochemical processes, where good overlap higher currents generally corresponding to greater
between forward and reverse scans suggests minimal capacitance.

Fig 5 Cyclic Voltammogram of Fabricated Composite Electrode in 1 M KOH (−0.2 to 0.8 V vs. Ag/AgCl, 10 mV/s)

The alkaline environment of 1 M KOH electrolyte matrix, this creates a flexible foundation, but one limited by
facilitates stable operation and enables clear observation of the inherent resistance of carbon-based conduction. The
both capacitive and faradaic processes. The absence of sharp breakthrough emerges through the gradual introduction of
current increases at the potential limits demonstrates the NiNPs, which transform the composite's electrical properties
material's electrochemical stability in this medium. This while simultaneously enhancing its mechanical robustness.
stability is particularly important for practical applications
where long-term cycling performance is required. The At lower NiNPs loadings (10%), the system begins its
observed charge storage behavior, whether primarily transformation, with metallic particles acting as bridges
capacitive, faradaic, or a combination of both, guides further between isolated carbon clusters. This stage represents more
optimization of the composite material's composition and than simple conductivity enhancement—it establishes the
structure. first elements of a stress-responsive network. The
nanoparticles preferentially occupy high-stress regions in the
IV. CONCLUSION polymer matrix, creating conductive pathways that naturally
align with mechanical load directions. As strain increases,
This research demonstrates an elegant convergence of these aligned pathways maintain connectivity even as the
sustainable materials engineering and advanced functional overall material deforms, explaining the observed 12%
performance in developing stretchable conductive composites. resistance change at 50% strain in the optimal composition.
The systematic investigation reveals how strategic
incorporation of nickel nanoparticles (NiNPs) into fruit peel- The transition to 20% NiNPs loading marks a critical
derived carbon matrices creates a material system where inflection point where conduction mechanisms fundamentally
electrical, mechanical, and electrochemical properties shift. Here, the material develops true hybrid behavior—not
synergistically enhance one another, rather than existing as merely a mixture of carbon and metallic conduction, but an
competing priorities. integrated system where each component enhances the
other's function. The carbon network prevents NiNPs
The foundation of this work lies in the innovative use of aggregation during deformation, while the metallic pathways
pyrolyzed banana and orange peels to create hierarchically provide low-resistance conduits that maintain conductivity
porous activated carbon (OPBLAC). This biomass-derived when carbon contacts separate under strain. This mutual
framework serves as both a structural scaffold and a reinforcement creates the observed plateau in mechanical
conductive pathway, its natural porosity providing ionic properties, where further NiNPs additions continue
accessibility while its carbonaceous structure offers electron improving conductivity without compromising stretchability.
transport routes. When combined with the elastomeric SIS

IJISRT25MAR1721 www.ijisrt.com 2315

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
The 30% NiNPs composition represents the pinnacle of In conclusion, this work achieves more than incremental
this synergistic integration. Electron microscopy reveals a improvement in stretchable conductors; it demonstrates a
self-organized structure where NiNPs form continuous paradigm where material components work in concert rather
networks while maintaining optimal spacing through carbon- than compromise. By respecting the inherent properties of
mediated separation. This delicate balance produces each constituent and carefully engineering their interactions,
simultaneous peaks in conductivity (4.07 S/cm), strain we've created a system where electrical, mechanical, and
capacity (220%), and electrochemical performance (218 F/g). electrochemical performance don't merely coexist, but
The system's intelligence lies in its hierarchical mutually enhance one another. This holistic approach to
organization—nanoscale NiNPs contacts provide metallic materials design points toward a new generation of
conduction, mesoscale carbon connections ensure multifunctional composites that transcend traditional
redundancy, and macroscale polymer elasticity performance tradeoffs, offering sustainable solutions for the
accommodates deformation. growing field of flexible electronics.

Electrochemical analysis further confirms this synergy. ACKNOWLEDGEMENT

The Ni²⁺/Ni³⁺ redox activity not only contributes pseudo
capacitance but also creates self-healing mechanisms at the The authors acknowledge the support of this research
electrode-electrolyte interface. During cycling, reversible work by the Biomimetic Lab at the Ningbo Innovation Center
oxidation/reduction processes naturally repair minor damage of Zhejiang University for providing fabrication and
to conductive networks, explaining the exceptional 95% designing facilities essential for carrying out this research
capacitance retention after 5000 cycles. This inherent self- work.
repair capability, combined with the material's mechanical
resilience, suggests unprecedented durability for stretchable  Conflict of Interest:
energy storage applications. The authors declare that they have no known competing
financial interests or personal relationships that could have
Critical examination of the underlying physics reveals appeared to influence the work reported in this paper.
why this system outperforms conventional approaches.
Traditional composites often face a zero-sum game between REFERENCES
conductivity and stretchability, enhancing one typically
degrades the other. Our biomimetic design overcomes this [1]. H. Suda, K. Haraya, Chem. Commun. (1997) 93–94.
through three key innovations: (1) utilizing nature-derived [2]. L.F. Velasco, B. Tsyntsarski, B. Petrova, T. Budinova,
carbon with intrinsic mesoporosity for strain accommodation, N. Petrov, J.B. Parra, C.O. Ania, J. Hazard. Mater. 184
(2) employing NiNPs as both conductive and reinforcing (2010) 843–848.
elements, and (3) engineering interfacial bonds that promote [3]. F. Rodriguez-Reinoso, Carbon 36 (1998) 159–175.
charge transfer while maintaining mechanical integrity. The [4]. Y. Lv, M. Liu, L. Gan, Y. Cao, L. Chen, W. Xiong, Z.
result is a material that doesn't just balance competing Xu, Z. Hao, H. Liu, L. Chen, Chem.Lett. 40 (2011)
demands but creates conditions where each property 236–238.
enhancement reinforces the others. [5]. D.W. Wang, F. Li, M. Liu, G.Q. Lu, H.M. Cheng,
Angew. Chem. Int. Ed. 47 (2008)373–376.
From an applications perspective, these findings [6]. D.R. Rolison, Science 299 (2003) 1698–1701.
redefine what's possible in flexible electronics. The [7]. T. Morishita, Y. Soneda, T. Tsumura, M. Inagaki,
demonstrated combination of metallic conductivity with Carbon 44 (2006) 2360–2367.
elastomeric stretchability opens doors for: Wearable sensors [8]. J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon,
maintaining signal integrity during body movement, P.L. Taberna, Science 313(2006) 1760–1763.
Stretchable energy storage devices that power flexible [9]. A. Thess, R. Lee, P. Nikolaev, H.J. Dai, P. Petit, J.
displays, Biomedical electrodes conforming to dynamic Robert, C.H. Xu, Y.H. Lee, S.G. Kim, A.G. Rinzler,
tissue surfaces. D.T. Colbert, G.E. Scuseria, D. Tomanek, J.E. Fischer,
R.E. Smalley, Science 273 (1996) 483–487.
The sustainability aspect adds another dimension, [10]. C. Journet, W.K. Maser, P. Bernier, A. Loiseau, M.L.
transforming agricultural waste into high-performance Delachapelle, S. Lefrant, P.Deniard, R. Lee, J.E.
electronic materials through scalable pyrolysis processes. Fischer, Nature 402 (1999) 276–279.
[11]. B. Zheng, C.G. Lu, G. Gu, A. Makarovski, G.
While challenges remain particularly in large-scale Finkelstein, J. Liu, Nano Lett. 2 (2002)895–898.
manufacturing consistency and long-term environmental [12]. M. Liu, L. Gan, C. Tian, J. Zhu, Z. Xu, Z. Hao, L.
stability, the fundamental principles established here provide Chen, Carbon 45 (2007) 3045–3046.
a roadmap for future development. The unexpected discovery [13]. T.W. Kim, I.S. Park, R. Ryoo, Angew. Chem. Int. Ed.
of strain-enhanced interfacial charge transfer in these 42 (2003) 4375–4379.
composites suggests even greater potential waiting to be [14]. B. Xu, F. Wu, R. Chen, G. Cao, S. Chen, Y. Yang, J.
unlocked through further investigation of dynamic structure- Power Sources 195 (2010)2118–2124.
property relationships. [15]. Y.I. Jang, N.J. Dudney, T.N. Tiegs, J.W. Klett, J.
Power Sources 161 (2006) 1392–1399.
[16]. B. Liu, H. Shioyama, T. Akita, Q. Xu, J. Am. Chem.

IJISRT25MAR1721 www.ijisrt.com 2316

Volume 10, Issue 3, March – 2025 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165 https://doi.org/10.38124/ijisrt/25mar1721
Soc. 130 (2008) 5390–5391.
[17]. M. Hu, J. Reboul, S. Furukawa, L. Radhakrishnan, Y.J.
Zhang, P. Srinivasu, H. Iwai, H.J. Wang, Y. Nemoto,
N. Suzuki, S. Kitagawa, Y. Yamauchi, Chem.
Commun. 47 (2011) 8124–8126.
[18]. B. Liu, H. Shioyama, H.L. Jiang, X.B. Zhang, Q. Xu,
Carbon 48 (2010) 456–463.
[19]. L. Radhakrishnan, J. Reboul, S. Furukawa, P.
Srinivasu, S. Kitagawa, Y. Yamauchi,Chem. Mater. 23
(2011) 1225–1231.
[20]. J.A. Hu, H.L. Wang, Q.M. Gao, H.L. Guo, Carbon 48
(2010) 3599–3606.
[21]. H. Li, M. Eddaoudi, M. O’Keeffe, O.M. Yaghi, Nature
402 (1999) 276–279.
[22]. A. Carton, A. Mesbah, L. Aranda, P. Rabu, M.
Francois, Solid State Sci. 11 ( 2009)818–823.
[23]. H.J. Liu, X.M. Wang, W.J. Cui, Y.Q. Dou, D.Y. Zhao,
Y.Y. Xia, J. Mater. Chem.20(2010) 4223–4230.
[24]. E. Raymundo-Pinero, F. Leroux, F. Beguin, Adv.
Mater. 18 (2006) 1877–1882.
[25]. G.D. Ruan, Z.Z. Sun, Z.W. Peng, J.M. Tour, ACS
Nano 5 (2011) 7601–7607.
[26]. T.H. Emaga, C. Robert, S.N. Ronkart, B. Wathelet, M.
Paquot, Bioresour. Technol.99 (2008) 4346–4354.
[27]. M. Thirumavalavan, Y.L. Lai, L.C. Lin, J.F. Lee, J.
Chem. Eng. Data 55 (2010)1186–1192.
[28]. M. Achak, A. Hafidi, N. Ouazzani, S. Sayadi, L.
Mandi, J. Hazard. Mater. 166 (2009)117–125.
[29]. V.N. Gunaseelan, Bioresour. Technol. 98 (2007)
1270–1277.
[30]. A. Bankar, B. Joshi, A.R. Kumar, S. Zinjarde,
Colloids Surf. B 80 (2010) 45 -50.
[31]. R.S.D. Castro, L. Caetano, G. Ferreira, P.M. Padilha,
M.J. Saeki, L.F. Zara, M.A.U.Martines, G.R. Castro,
Ind. Eng. Chem. Res. 50 (2011) 3446–3451.
[32]. A. Bankar, B. Joshi, A.R. Kumar, S. Zinjarde, Mater.
Lett. 64 (2010) 1951–1953.
[33]. A. Bankar, B. Joshi, A.R. Kumar, S. Zinjarde,
Colloids Surf. A 368 (2010) 58–63.

IJISRT25MAR1721 www.ijisrt.com 2317