Development of cellulose-based composite for energy storage applications

Separators play a crucial role in enhancing the electrochemical performance of lithium-ion batteries (LIBs). However, achieving separators with outstanding electrochemical performance and high stability remains a challenge. Bio-separators have emerged as promising alternatives due to their exceptional porosity and stability. In this study, biomembranes based on polyvinylidene fluoride (PVDF) with varying contents of microcrystalline cellulose/tetraethyl orthosilicate (MCC/TEOS) were developed and employed as separators in LIBs. The biomembrane with 3 wt% MCC/TEOS exhibited remarkable porosity (92.3%) compared to the plain PVDF membrane (82.5%), enhancing electrolyte absorption and reducing resistance, resulting in superior ionic conductivity (0.5144 mS/cm). LIB cells using this optimized membrane consistently showed stable charge/discharge profiles at 0.2C, achieving a specific capacity of 98 mAh/g, significantly outperforming the plain PVDF membrane (43 mAh/g). These results highlight the potential of MCC/TEOS as an effective biofiller for enhancing LIB separator performance.Additionally, a composite sheet comprising bacterial cellulose (BC) and polyaniline (PAN) integrated with activated carbon (AC) was fabricated using suction pump and freeze-drying techniques. The incorporation of activated carbon significantly increased the composite's specific capacitance to 73.051 F/g, as demonstrated by cyclic voltammetry (CV) analysis. Fourier transform infrared spectroscopy revealed hydrogen bonding interactions between the -OH groups of bacterial cellulose and the -NH groups of polyanilines, while scanning electron microscopy confirmed the random distribution of activated carbon within the BC network. Optimization of the activated carbon ratio reduced charge-transfer resistance (Rct), enhancing electrical conductivity. These findings demonstrate the potential of the BC/PAN/AC composite as a promising candidate for supercapacitor applications, offering a nano-based platform with superior electrochemical properties.