Electrospinning of Bacterial Cellulose Modified with Acetyl Groups for Polymer Electrolyte Li-Ion Batteries

A cellulose acetate (CA) membrane as an acetylation product of bacterial cellulose (BC) has been successfully fabricated by electrospinning (e-spin). CA was utilized to achieve the optimal polymer electrolytes’ (SPEs) requirements of high ionic conductivity and good thermal and electrochemical stability. E-spin has received a great deal of attention in order to enhance the surface of membranes that is both flexible and strong, which will be effective in obtaining a low interface resistance for a better contact polymer electrolyte/electrode. The e-spin of CA SPEs forms a three-dimensional network of interconnected porosity. Polar ester groups in CA e-spin not only present the homogeny porosity of the SPEs but also played an important role in facilitating the dissociation of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). According to XPS, peaks of TFSI binding energy CA that are higher than BC are thought to represent the interaction between the polymer chain and the TFSI cation. TFSI− was found to have accumulated around C=O, and Li+ could diffuse quickly. This is supported by the fact that the ionic conductivity (2.68 × 10−3 Scm−1) of CA is better than BC (8.86 × 10−4 Scm−1). The change in dielectric permittivity (ε) as a function of frequency in CA SPEs shows more decay at higher frequencies, indicating better electrode polarization due to CA SPE/electrode contact than BC. The analysis of the modulus (M) shows that CA SPEs in this study are more ionic conductors than BC. CA SPEs also outperformed BC in terms of stability window performance (4.5 V). The discharge capacities of 40 mA h−1 for CA SPEs exhibit an oxidation peak at 4.25 V and a reduction peak at 2.9 V, which are comparatively higher than the charge–discharge of 20 mA h−1 for BC SPEs, which display an oxidation peak at 3.5 V and a reduction peak at 2.8 V.