Abstract
Silicon (Si) has a high theoretical capacity of 4200 mAh/g in lithium-ion batteries anode; however, it faces three main difficulties: an unstable Solid Electrolyte Interface (SEI), particle pulverization, and volume expansion. In this work, we present a highly efficient anode material for Lithium-Ion CR2032 3V half-cell using Activated Charcoal (AC), Carbonized Sucrose Powder (CSP), and Hierarchically Porous Spherical Cluster Silicon Nanoparticles (HPSC-SiNPs). This anode is designed using carbon to overcome three issues associated with Si. Additionally, the anode charge-storage behavior was examined using cyclic voltammetry (CV). The anode in this investigation showed outstanding electrochemical performance and structural stability. Additionally, Faradaic charge-storage behavior was demonstrated by CV analysis. At 0.56 C, the anode-specific capacity was 3,412.44 mA h/g, and the energy density was 204.74 W h/kg. The initial specific capacity of the half-cell, 3,103.42 mA h/g, decreased to 1,674.53 mA h/g after 200 cycles at a rate of 2.57 C. Initially, the capacity and efficiency of Si appear promising; however, they decline rapidly with increasing cycle number. In contrast, the HPSC-SiNPs-CSP-AC anode, incorporating activated charcoal and carbonized sucrose powder, demonstrated promising and effective performance.
1 Introduction
In the current era, high-energy-density lithium-ion batteries (LiBs) have become increasingly important as renewable energy technologies continue to develop and demand for these batteries grows to meet rising energy needs (; ). One of most effective approaches to satisfy the growing need for higher energy density in next-generation LiBs is the use of electrode materials with high theoretical capacity. Silicon (Si) has emerged as the most promising anode material to replace conventional graphite anode due to its exceptionally high theoretical capacity of 4,200 mA h/g, nearly ten times greater than that of commercial graphite (372 mA h/g) (; ; ).
The three main problems encountered with Si anode during lithiation and delithiation are (i) large-volume swelling (it swells by more than 300%). (ii) Pulverization. Both of these problems lead to cracking of Si and its conversion to powder (). Also, (iii) the solid electrolyte interface layer leads to continuous consumption of electrolyte, which leads to a decrease in efficiency. This leads to a rapid decrease in Si anode capacity and, consequently, a decrease in electrochemical performance during repeated cycles. A large amount of research effort is underway to overcome these problems at the earliest, primarily by increasing the structural stability and electrical conductivity of Si anode. Various Si-based structures have been developed recently to overcome volume swelling and reduce internal stresses. Such as thin films, nanotubes, nanowires, nanosheets, hollow nanospheres, and porous frameworks. In addition, incorporating conductive materials such as metal nanoparticles (NPs), carbon-based structures, polymers, and MXene has been effective in improving electrical conductivity () and stabilizing electrode performance. Research has increased Si anode electrical conductivity to reduce internal stress by using thin films, nanowires, hollow nanospheres, nanosheets, and porous frameworks to accommodate solid bubble dimensional changes (). Furthermore, the incorporation of conductive materials, including metal nanoparticles (NPs), carbon-based matrices, polymers, and MXene (), has been shown to improve electrical conductivity and stabilize electrode performance. Although all the above solutions show promising results, their implementation often requires expensive raw materials, complex synthesis processes, and harsh reaction conditions. This results in significant limitations in large-scale production (scalability). For these reasons, there is an urgent need to develop solutions to prepare high-performance Si-based anode materials in a facile, cost-effective, and effective manner (; ).
The focus should be on selecting readily available Si sources, increasing electrochemical efficiency, targeting cost reduction, creating suitable Si-based structures, and adopting technologies that enable the fabrication of such simple processes. Metallurgical-grade Si (MG-Si) is particularly important as a low-cost and mass-produced source of Si. This Si is a very good alternative raw material in large quantities (; ; ). The metal-assisted chemical etching (MACE) method is attracting special attention in research due to its simplicity, low cost, and ability to produce Si nanowires with porous Si structures and controlled microstructures. To remove metal nanoparticles (NPs) deposited from the porous structures, the MACE process usually includes an acid wash step to ensure high-quality porous structures. Proper control and confinement of metal nucleation in the pore channels can further improve the electrical conductivity of Si-based compounds. As a result, their overall electrochemical performance also increases.
This work aims to enhance electrochemical performance by utilizing pre-synthesized hierarchically porous spherical cluster silicon nanoparticles (HPSC-SiNPs) from Sigma-Aldrich and fabricating electrodes with carbonized sucrose powder and activated charcoal. The results demonstrate improved cyclic stability and superior rate performance. This study not only provides a simple approach to enhance the electrochemical properties of pre-made HPSC-SiNPs-CSP-AC but also offers a viable pathway for large-scale production of high-performance anodes for rechargeable Lithium-Ion CR2032 Half-Cell.
2 Experimental details
2.1 Materials
Hierarchically porous spherical cluster silicon nanoparticles (HPSC-SiNPs) with a minimum particle size of 100 nm and 98% purity were used from Sigma-Aldrich. Activated charcoal (AC), N-methyl-2-pyrrolidone (NMP), and polyvinylidene fluoride (PVDF) were obtained from Sigma-Aldrich. Sigma-Aldrich’s sucrose was used to prepare carbonized sucrose powder (CSP).
In addition, Lithium-Ion CR 2032 3V Half-Cell equipment required for the preparation of HPSC-SiNPs-CSP-AC anode was obtained from Sigma-Aldrich. For electrolyte preparation, a commercial LP30 solution (1 M LiPF6 in a 1:1:1 mixture of diethyl carbonate (DEC), ethylene carbonate (EC), and dimethyl carbonate (DMC)) was obtained from Sigma-Aldrich. Additionally, 0.6 mm-thick lithium metal and Whatman™ filter paper were sourced from Sigma-Aldrich. All reagents were used as supplied, without further purification ().
2.2 Preparation of HPS-sinps-csp-ac anode electrode and lithium ion CR 2032 3V half-cell fabrication
We prepared a composite mixture to fabricate an HPSC-SiNPs-CSP-AC anode electrode for assembly in a Lithium-Ion CR 2032 3V Half-Cell. The mixture, consisting of HPSC-SiNPs, PVDF (in NMP), carbonized sucrose powder, and activated charcoal in a 70:10:10:10 ratio, was stirred for 3 h at 1,000 rpm to achieve a homogeneous and consistent slurry. This thick slurry was Doctor Blade-coated onto copper foil, dried at 100 °C under vacuum for 12 h, and cut into 16 mm discs, with an active material loading of approximately 2.01 mg/cm2 ().
During cell assembly, Whatman™ filter paper was used as the separator due to its high electrolyte absorption and wettability, ensuring consistent electrode contact and good ionic conductivity-properties widely recognized in lab-scale Lithium-Ion CR 2032 3V Half-Cell applications. Lithium foil was used as the counter electrode. A commercial LP30 electrolyte (1 M LiPF6 in dimethyl carbonate (DMC), ethylene carbonate (EC), and diethyl carbonate (DEC)) was used. The entire assembly was conducted in an argon-filled glove box, with humidity and oxygen levels strictly maintained below 0.1 ppm to ensure an inert atmosphere and reliable cell fabrication.
2.3 Material characterization
The structural properties and crystallinity of samples were studied using X-ray diffraction (XRD). A Rigaku MiniFlex-600 system was used for this analysis, with Cu Kα radiation and a 2θ scan range of 10°–90°. The JASCO Fourier-transform infrared (FTIR) spectroscopy 6,100 instrument was used to study the functional groups on the surface. The pore size and specific surface area of material were determined using Brunauer–Emmett–Teller (BET) characterization with the Barrett–Joyner–Halenda (BJH) model. The NOVA NANOSEM 450 instrument was used for field-emission scanning electron microscopy (FE-SEM) to determine the size and morphological characteristics of crystalline particles in the materials, as well as for EDS mapping. The contact angle was determined by measuring the wettability and surface energy of electrode after electrode preparation using a contact angle meter HO-IADCAM-01 from Holmarc OptoMechatronics Pvt. Ltd (India) (). Thermogravimetric analysis (TGA) of HPSC-SiNPs anode was performed using the Universal V4.5A TA Instruments, Instrument: SDT Q600 V20.9 Build 20, to determine the weight percentage of HPSC-SiNPs structure (see Supplementary Material for details).
2.4 Electrochemical characterization
Electrochemical performance parameters were evaluated using the Galvanostatic Charge-Discharge (GCD) method. The following Equations 1 and 2 were employed to calculate specific capacity () and C-rate with high accuracy:where ‘m’ in Gram is the mass of active electrode deposited material, ‘’ is applied current, ‘dt’ is the discharging time in ‘s’where 1 C = 1 Hour = 3,600 Second and Time in (s) (Discharging or Charging).
The energy density (E) was accurately determined using the following mathematical expressions, Equation 3 ():
3 Results and discussion
3.1 Structural analysis
Figure 1A shows HPSC-SiNPs XRD peaks for crystalline Si and a broad amorphous SiO2 hump at ∼14°. The labeled peaks and features shown in the Figure provide important information about the material’s structural organization. At the same time, the broad peak found at 14° is associated with amorphous SiO2. This amorphous state indicates partial oxidation of Si NPs. This may be due to surface oxidation during handling and exposure to air or during synthesis. This amorphous SiO2 layer can act as a passivation layer. Thus, it protects the main C-Si from further oxidation. Prominent XRD peaks at 28.91°, 47.76°, 56.69°, 69.69°, and 76.97° correspond to Si (111) (220) (311) (400), and (331) planes, improving electrochemical stability. These peaks match the reference pattern for Si (JCPDS No. 27–1,402) and confirm the presence of a highly C-Si phase (). The Scherrer equation (Equation 4) was used to calculate the crystallite size (D) based on XRD peak broadening:
FIGURE 1
Here, D is the crystallite size, λ is the X-ray wavelength, β is the Full Width at Half Maximum (FWHM) of diffraction peak, and θ is the Bragg angle. Using this equation for the (111) and (002) peaks, the average crystallite size was calculated as 96.75 nm, which closely matches the ∼100 nm particle size observed by TEM (Sigma Aldrich).
The lattice constants (a) for the (111) and (002) planes were determined to be 1.67 Å and 2.9 Å, respectively, confirming the cubic crystal structure of Si nanoparticles. The high intensity of (111) peak reflects a well-ordered crystalline structure, which is beneficial for lithium-ion storage efficiency (). Lower intensity peaks in the composite indicate the presence of amorphous phases, such as SiO2, which can attenuate X-ray interactions with crystalline Si and result in peak reduction (). The presence of amorphous SiO2 also helps stabilize the material by mitigating volume expansion during lithiation/delithiation, a common challenge for Si-based anode (). Overall, the average dimension of HPSC-SiNPs anode material is about 96.75 nm, confirming the coexistence of both crystalline and amorphous SiO2 phases. This combination provides a balance between high conductivity and structural stability, making the material a promising candidate for high-performance lithium-ion CR 2032 3V Half-Cell ().
3.2 Fourier transforms infrared spectroscopy
The FTIR spectrum (Figure 1B) of HPSC-SiNPs anode sample provides crucial information on the functional groups present on the material’s surface. A broad absorption band between 3,300 and 3,500 cm-1 is attributed to silanol (Si-OH) groups, which are typically formed during synthesis or upon exposure to atmospheric moisture (). These groups enhance surface wettability, thereby improving electrolyte penetration and lithium-ion diffusion during electrochemical cycling ().
The peak at 1,619.22 cm-1 is assigned to H-O-H bending vibrations, indicating the presence of adsorbed water molecules, which impart partial hydration to the surface. This enhances the hydrophilic nature of material and may support ionic conductivity in the electrode (). Distinct Si-O-Si asymmetric stretching vibrations are observed at 1,192.31 cm-1, 1,084.17 cm-1, and 885.56 cm-1, characteristic of siloxane bonds in the SiO2 network. These confirm the presence of an amorphous SiO2 matrix, which acts as a structural stabilizer and helps minimize volume expansion during charge–discharge cycles (). This observation is consistent with XRD analysis, which also showed both crystalline and amorphous SiO2 phases. A peak at 470.67 cm-1 corresponds to Si-O bending vibrations, reflecting deformation modes within the SiO2 framework (). These vibrational features highlight the chemical stability and mechanical robustness imparted by the SiO2 component.
Notably, the absence of peaks in the 2,852–2,924 cm-1 region, commonly associated with C-H stretching vibrations, suggests high material purity with minimal organic or carbon contamination (). Peaks at 1868 cm-1 and 2,258 cm-1 are assigned to Si–H stretching modes, indicating some residual Si–H bonds on the particle surfaces (). Overall, the FTIR analysis confirms the presence of Si–O–Si bonds in both crystalline and amorphous forms, aligning with structural findings from XRD. The detection of water-associated bands suggests partial hydration, which could influence surface reactivity and electrochemical performance. These detailed spectral features are essential for understanding and optimizing the functionality of HPSC-SiNPs anode material.
3.3 Surface area analysis
The Brunauer–Emmett–Teller (BET) isotherm is a key technique for surface characterization, describing the relationship between gas adsorption and relative pressure (P/P0) on a solid surface. For the HPSC-SiNPs anode, the BET type III isotherm (Figures 1C,D) shows a sharp rise at low relative pressure, indicating monolayer adsorption. As pressure increases, an inflection point appears, marking the transition to multilayer adsorption, followed by a plateau at surface saturation. Hysteresis loops during desorption reveal non-ideal, porous structures and capillary condensation effects. The HPSC-SiNPs anode exhibits a specific surface area of 61.89 m2/g and an average pore diameter of 38.50 nm, confirming a mesoporous structure. These features improve electrolyte accessibility and ion diffusion, which are critical for electrochemical performance. Barrett–Joyner–Halenda (BJH) analysis further supports the mesoporous nature and detailed pore size distribution. Together, BET and BJH analyses provide essential insights into the porosity and structural properties of material, directly impacting its suitability for battery applications (; ; ).
3.4 Raman spectrum analysis
Raman spectroscopy (Figure 1E) was used to analyze the structural features of HPSC-SiNPs anode material. A distinct peak at 523 cm-1 was observed, corresponding to the first-order Raman active mode of Si (Si-Si covalent bond stretching) (; ). This sharp, well-defined peak confirms the highly ordered lattice and high crystallinity of the C-Si phase. The absence of broad peaks associated with amorphous Si or other phases further supports the material’s crystalline nature and phase stability. The intensity and precise position of 523 cm-1 peak indicate structural purity, minimal lattice defects, and low residual stress or strain in the Si lattice (; ). Raman shift analysis thus provides important information on lattice dynamics, material quality, and possible strain effects. Overall, the Raman results demonstrate that the HPSC-SiNPs anode possesses a well-protected, crystalline Si lattice, making it a strong candidate for use in high-performance Lithium-ion CR 2032 3V Half-Cell, with expected benefits in capacity, stability, and electrochemical performance.
3.5 Contact angle measurement
The use of liquid-based electrolytes has a direct positive effect on the surface behavior of solid anode electrodes, which in turn improves their electrochemical performance (). Therefore, a lower contact angle and higher surface energy together lead to improved electrochemical performance. Contact angle measurement depends on purity, particle size, cleanliness, heterogeneity, and surface roughness (; ). In energy storage applications, superhydrophilic properties increase the surface area for interaction between electrolyte ions and the active electrode material. Figure 1F shows the water contact angle on the surface of HPSC-SiNPs anode, which testifies to its remarkable superhydrophilicity (). Water droplets spread completely and form a uniform, thin coating at a 0° angle.
3.6 Morphological analysis
The size and structural properties of HPSC-SiNPs anode were analyzed by field emission scanning electron microscopy (FE-SEM). The FE-SEM images of HPSC-SiNPs anode are shown in Figures 1G,H. The micrographs reveal that Si NPs anode shows porous spherical cluster formed by aggregated particles with dimensions of 50–200 nm. This morphology enables high energy and power densities via diffusion and surface charge-storage mechanisms (). Electrical conductivity and thermal stability are improved by adding materials like carbonized sucrose powder, nanographite, or graphene oxide (; ). Additionally, the hierarchically porous structure improves charge-transfer capability, lowers interfacial resistance, and increases electrolyte absorption (). The EDS analysis included: (a) elemental composition with weight (%) and atom (%), (b) a selected portion of the HPSC-SiNPs anode, (c) a secondary electron (SE) image showing oxygen (O) and silicon (Si), (d) elemental mapping of O and Si, (e) O, and (f) Si in Supplementary Figure S1 (see Supplementary Material for details).
3.7 Electrochemical study
3.7.1 Cyclic voltammetry
Cyclic voltammetry (0.0–3.0 V) of HPSC-SiNPs-CSP-AC anode in a CR2032 half-cell was measured at scan rates from 20 to 200 mV/s (Figure 2A). There is no noticeable intercalation peak in the CV curves of HPS-SiNPs-CSP-AC composite anode between 1.0 V and below 0.5 V, suggesting that lithium intercalation is absent in this voltage range. Rather, Figure 2A displays redox peaks at ∼1.5 V and ∼1.0 V that correspond to lithium insertion and deinsertion. These profiles demonstrate how the combination of faradaic and pseudocapacitive charge-storage techniques enables the high-rate performance of a Lithium-Ion CR 2032 3V Button-Cell (). Bulk lithium storage, a characteristic of traditional Si-based anodes, is made easier by HPS-SiNPs ().
FIGURE 2
Additionally, surface-dominated HPSC-SiNPs-CSP-AC anode exhibit faradaic behavior, which improves their electrochemical performance. When fully lithiated, Si experiences a volume expansion of around 400%, which breaks the particles and pulverizes the electrodes (). Active particles lose contact due to mechanical degradation, which lowers their capacity and conductivity. The SEI layer grows continuously as a result of frequent volume changes, which worsens the electrochemical performance. The following (Equations 5–8) are the anodic and cathodic reactions during lithiation and delithiation, ():
During lithiation.
Cathode reaction
Anode reaction
During delithiation.
Cathode reaction
Anode reaction
To evaluate stability, CV was measured at 200 mV/s across 10–700 cycles; profiles are displayed in Figure 2B. According to Bouguern et al. (), stability measurements revealed no intercalation peak between 1.0 and 0.9 V vs. Li/Li+. Signals of Li/Li+ appeared at about 1.0 V, whereas redox pairs indicating lithium integration appeared at about 1.6 V (). Over several cycles, the CV profile did not change, indicating sustained redox activity and electrochemical performance preservation (). Because of its distinctive porous structure and mixed faradic-pseudocapacitive charge storage processes, the HPSC-SiNPs-CSP-AC anode displays high rate capability and steady redox behavior. Despite obstacles including volume expansion and SEI generation, structural design and surface alterations can enhance electrochemical performance and cycling stability.
3.7.2 Diffusion coefficient study
The total charge storage shown by the electrode can include contributions from both capacitive and diffusion-controlled processes (). Capacitive charge storage involves electro-adsorption of electrolyte ions on the electrode surface, then surface redox reactions occur (). In contrast, the diffusion-controlled process requires the incorporation of electrolyte ions into the electrode structure, where they are involved in bulk redox reactions (). The charge storage kinetics of HPSC-SiNPs-CSP-AC anode was analyzed using the power-law relation (Equation 9), which is shown in ():where, Ip (mA) is the peak current, ν (mV/s) denotes the scan rate and a and b are coefficients. The parameter ‘b' determines the charge storage mechanism. For b ≈ 0.5, the charge storage is predominantly diffusion-controlled, while for b ≈ 1, it is primarily governed by capacitive processes. From the log(I) versus log(ν) plot shown in Figure 2C, the results indicate that HPSC-SiNPs-CSP-AC anode stores a majority of charge via diffusion-controlled processes. The current response was deconvoluted using the following equation (Equation 10) to accurately quantify the contributions from capacitive and diffusion-controlled mechanisms ():where represents the capacitive contribution and corresponds to the diffusion-controlled contribution. The slope and intercept derived from the linear fit of graph yield the values of and , as illustrated in Figure 2E. The corresponding contributions from capacitive and diffusion-controlled mechanisms are shown in Figure 2C for HPSC-SiNPs-CSP-AC composite anode. The results reveal that as the scan rate decreases, the diffusion-controlled contribution increases, resulting in higher specific capacitance and capacity (). The capacitive process in HPSC-SiNPs-CSP-AC anode stores 37.79% of total charge at 200 mV/s, largely due to increased film thickness allowing LiPF6 electrolyte penetration. The observed low capacitive contribution suggests that bulk redox reactions driven by electrolyte ion insertion take place in most of charge storage electrodes. According to the results, increasing the material weight and thickness of coated electrode improves the electrolyte diffusion and redox activity, which enhances the charge storage capacity of HPSC-SiNPs-CSP-AC anode.
3.7.3 Galvanostatic charge-discharge
The electrochemical performance of the HPS-SiNPs-CSP-AC anode in a CR 2032 3V lithium-ion half-cell was evaluated using galvanostatic charge–discharge (GCD) measurements at various C-rates: 0.56, 1.24, 2.94, 2.57, 9.38, 25.17, 283.24, 904.52, 2,117.65, and 2,155.69 C, respectively. The measurements were performed in the open-circuit voltage window of 0.0–3.0 V (vs. Li/Li+), as shown in Figure 3A. The discharging specific capacity of HPS-SiNPs-CSP-AC anode ranged from 3,412.44 to 46.39 mA h/g. These findings indicate that the nanoscale particle size of HPS-SiNPs-CSP-AC anode enhances both the active surface area and electrochemical activity (). Figure 3A shows the GCD curves at different C-rates of 0.56, 1.24, 2.94, 2.57, 9.38, 25.17, 283.24, 904.52, 2,117.65, and 2,155.69 C. The voltage plateaus observed during discharge at 0.20, 0.16, 0.16, 0.15, 0.15, 0.06, 0.21, 0.19, 0.15, and 0.15 V (vs. Li/Li+) correspond to electrolyte decomposition and formation of solid electrolyte interphase (SEI) layer at all current densities (). The insertion of Li ions into HPS-SiNPs-CSP-AC anode leads to the gradual formation of Li-Si alloys, which provides substantial volume expansion of Si lattice. The Li-Si alloy phase Li22Si5 is formed at a specific capacity of about 4,200 mA h/g, while the Li15Si4 elementary phase is formed at about 3,579 mA h/g. The Li21Si5 phase is formed when the specific capacities are 1,400–2000 mA h/g. Figure 3B also presents the specific capacity of the HPSC-SiNPs-CSP-AC anode cell at various C-rates, displayed as a bar diagram. Table 1 gives the electrode name, C-rates (C), current (A/g), discharge time (s), discharge specific capacity (mAh/g), energy density (Wh/kg), for HPS-SiNPs-CSP-AC anode for Lithium Ion CR 2032 3V Half-Cell. This study shows that current and film thickness have a crucial role in optimizing the electrochemical performance of HPSC-SiNPs-CSP-AC anode for high energy and high power applications.
FIGURE 3
TABLE 1
| Electrode Name | C-rates (C) | Current in (A/g) | Discharging time in (s) | Discharging specific capacity in (mAh/g) | Energy density (Wh/kg) |
|---|---|---|---|---|---|
| HPSC-SiNPs-CSP-AC anode | 0.56 | 2 | 6,142.39 | 3,412.44 | 204.74 |
| 1.24 | 4 | 2,905 | 3,227.78 | 193.66 | |
| 2.94 | 6 | 1,226 | 2043.33 | 122.60 | |
| 2.57 | 8 | 1,402 | 3,115.56 | 186.93 | |
| 9.38 | 10 | 384 | 1,066.67 | 64 | |
| 25.17 | 20 | 143 | 0,794.44 | 47.66 | |
| 283.24 | 40 | 12.71 | 0,141.22 | 8.47 | |
| 904.52 | 60 | 3.98 | 0,066.33 | 3.98 | |
| 2,117.65 | 80 | 1.7 | 0,037.78 | 2.26 | |
| 2,155.69 | 100 | 1.67 | 0,046.39 | 2.78 |
Electrode name, C-rates (C), current (A/g), discharge time (s), discharge specific capacity (mAh/g), energy density (Wh/kg), for HPSC-SiNPs-CSP-AC anode for Lithium Ion CR2032 3V Half-Cell.
The GCD stability of HPSC-SiNPs-CSP-AC anode in a Lithium Ion CR 2032 3V Half-Cell was observed over 200 cycles, with discharge profiles ranging from 3,103.42 mA h/g to 1758.65 mA h/g (C-rate at 2.57 C). These profiles are shown in Figure 3C. The analysis showed that the Li-Si alloy formation phases during cycling mainly appeared as Li15Si4 in the initial stage, which later changed to Li21Si5 (). Despite this, the structural integrity was maintained during the test. This phase shows the stability of material, which can withstand lithiation and delithiation without major degradation. There was a gradual decrease in the specific capacity and capacitance with the increase in cycles, indicating a slight decrease in electrochemical performance due to the thickening and volume expansion of SEI layer associated with the Li-Si alloy changes (). These results highlight the potential of HPSC-SiNPs-CSP-AC anode for high-performance lithium-ion CR 2032 3V Half-Cell, offering both high specific capacity and excellent cycle stability.
The rate capability of a rechargeable lithium-ion CR 2032 3V half-cell was evaluated using galvanostatic charge-discharge (GCD) measurements at various C-rates (0.56, 1.24, 2.94, 2.57, 9.38, 25.17, 283.24, 904.52, 2,117.65, and 2,155.69 C) as shown in Figure 3D. The specific capacities (mAh/g) showed systematic variations according to the phase transition. From first to 10th cycle, the capacities decreased from 3,447.58 to 3,101.39 mA h/g at a C-rate of 0.56 C, which was sufficient to form Li15Si4 phase. From the 11th to the 20th cycle, stable capacities were observed, ranging from 3,230.95 to 3,230.51 mA h/g at a C-rate of 1.24 C in the same phase. From 21st to 30th cycles, the capacities decreased to 2033.41 mA h/g at a C-rate of 2.94 C, establishing the Li21Si5 phase. It dropped to 44.79 mA h/g at the 100th cycle (at a C-rate of 2,155.69 C) but remained stable at 1994.5 mA h/g (at a C-rate of 0.56 C) from the 101th to the 110th cycles, which was associated with Li13Si4 phase. These results show a stable phase transition and good capacity retention, despite gradual fade (). This study suggests that HPSC-SiNPs-CSP-AC anode can be used in high-performance Lithium Ion CR 2032 3V Half-Cell. The volume of Si atoms in the Li22Si5 alloy is 4 times larger, while in the Li13Si4 alloy it is 3.3 times larger (). This leads to a four-fold increase in the volume of Si lattice, which causes electrode cracks and fractures (). As a result, the active materials lose electrical contact, which reduces capacity (). Si rapidly converts to Li15Si4 at room temperature during lithiation, which then reverses to Si through a series of transitions during delithiation ().
3.7.4 Electrochemical impedance spectroscopy
Figure 4 show impedance spectroscopy results, showing the resistance behavior before and after cycling stability, for a Lithium Ion CR 2032 3V Half-Cell. For the pre-cycling and post-cycling stability tests, the Nyquist plots show an oblique line in the low-frequency region and a suppressed semicircle in the high-frequency region. Both solution resistance (Rs) and electronic contact are related to the resistance associated with lithium ion and electron conduction at the solid electrolyte interface (SEI, Rf), as well as the charge transfer resistance (Rct) during lithium ion transport in the active material (). The diffusion of lithium ions into the electrode is represented by the linear low-frequency region (Zw). As shown in the insets of Figure 4, the Nyquist plot can be fitted with an equivalent circuit model. Here Zw accounts for the Warburg resistance, which describes the diffusion of Li+ into the electrode, while Cf represents the surface film capacitance and Cct corresponds to the Faradic of HPSC-SiNPs-CSP-AC anode. The Rs values for anode electrode are similar, but the addition of activated carbon and black sucrose powder to HPSC-SiNPs-CSP-AC anode reduces Rf. These additives increase the stability of SEI, reduce the continuous decomposition, and help form a relatively thin and conductive SEI layer (). The impedance spectra of HPSC-SiNPs-CSP-AC anode have both semicircles and angular lines. The oblique line showing the volume expansion during the insertion and extraction of Li+ is associated with the high-frequency semicircle diffusion resistance (). After 700 cycles, the observed volume expansion of HPSC-SiNPs-CSP-AC anode increases. These results indicate that the HPSC-SiNPs-CSP-AC based anode effectively reduces the electrode charge transfer resistance, facilitates Li+ movement and supports volume expansion.
FIGURE 4
4 Conclusion
This study developed a porous spherical cluster silicon nanoparticles, carbonised sucrose powder, and activated charcoal (HPSC-SiNPs-CSP-AC) anode for a Lithium Ion CR 2032 3V Half-Cell, demonstrating exceptional electrochemical performance. Structural analysis using XRD confirmed the presence of an amorphous SiO2 phase and crystalline silicon (c-Si) nanoparticles (∼96.75 nm), while BET measurements confirmed a mesoporous architecture with a specific surface area of 61.89 m2/g and an average pore diameter of 38.50 nm. Raman spectroscopy found a sharp Si-Si bond vibration peak at 523 cm-1, highlighting the structural stability of material. FE-SEM images showed porous spherical clusters (50–200 nm), providing good electrolyte infiltration and fast ion transport. Also, the zero-degree contact angle confirmed uniform electrode coatings and better adhesion. Cyclic voltammetry (CV) measurements at 200 mV/s scan rate validated the stable performance over 700 cycles, showing the materials resilience and durability during long-term operation. Also, the charge storage mechanism integrated faradaic processes, leading to 37.79% capacitive contribution at high scan rates and dominant diffusion-controlled behavior at low scan rates, ensuring perfect insertion and transport of lithium ions. The synthesized anode showed high specific capacity (3,412.44–46.39 mA h/g). It also showed high energy density (204.74–2.68 W h/kg). GCD stability evaluation at 8 A/g (2.57 C) over 200 cycles observed a gradual decline in both capacitance and capacity due to thickening of SEI layer and Li-Si alloy transition (Li15Si4 → Li21Si5 → Li13Si4), while phase stability and structural integrity were preserved. The reversible recovery of capacitance and capacity remarkably showed the ability of material to protect its volume from expansion-induced strain and maintain excellent cycle stability. Overall, the HPSC-SiNPs-CSP-AC anode is a high-performance, stable, and scalable solution for next-generation Lithium Ion CR 2032 3V Half-Cell applications. It delivers superior energy, strong cycle stability, and excellent rate capabilities to meet advanced energy storage requirements.
Statements
Data availability statement
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
Author contributions
ST: Methodology, Validation, Data curation, Conceptualization, Visualization, Investigation, Writing – original draft. RH: Writing – review and editing, Methodology, Formal Analysis. RK: Funding acquisition, Writing – review and editing, Formal Analysis, Project administration, Supervision. HJ: Project administration, Writing – review and editing, Funding acquisition, Supervision. DM: Writing – review and editing. SS: Formal Analysis, Writing – review and editing. CL: Project administration, Formal Analysis, Funding acquisition, Supervision, Writing – review and editing.
Funding
The author(s) declared that financial support was received for this work and/or its publication. We acknowledge funding from D. Y. Patil Education Society (Deemed to be University). Also, this research is supported by Centre for Materials for Electronics Technology (C-MET), Pune for providing a battery fabrication system and Central Instrumentation Facility, Department of Chemistry and Physics, Savitribai Phule Pune University, Pune for providing a physico-chemical characterizations instruments facility.
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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The author(s) declared that generative AI was not used in the creation of this manuscript.
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Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fbael.2026.1913828/full#supplementary-material
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Summary
Keywords
enhanced stability, excellent rate performance, lithium-ion CR2032 half-cell, maximum energy density, stable mid-cycle
Citation
Thombare S, Humane R, Kalubarme R, Jadhav H, Malavekar D, Shaikh S and Lokhande C (2026) Dual mechanism enhanced capacitive storage and diffusion kinetics in hierarchically porous spherical cluster silicon nanoparticles-carbonized sucrose-activated charcoal anode enable high energy in lithium-ion CR2032 half-cell. Front. Batter. Electrochem. 5:1913828. doi: 10.3389/fbael.2026.1913828
Received
19 June 2026
Revised
30 July 2026
Accepted
05 August 2026
Published
11 September 2026
Volume
5 - 2026
Edited by
Meysam Heydari Gharahcheshmeh, San Diego State University, United States
Reviewed by
Zhao Fang, Henan Institute of Technology, China
Ntalane Sello Seroka, Council for Scientific and Industrial Research, South Africa
Updates
Copyright
© 2026 Thombare, Humane, Kalubarme, Jadhav, Malavekar, Shaikh and Lokhande.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Sohan Thombare, sohanthombare98@gmail.com
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