Cellulose microspheres enhanced polyvinyl alcohol separator for high-performance lithium-ion batteries

Separators typically play an important role in enhancing the electrochemical performance of lithium-ion batteries (LIBs), while the preparation of separators suffers good electrochemical performance and high stability. In this study, regenerated porous cellulose microspheres (RCM) were innovatively fabricated and the biodegradable RCM/Polyvinyl alcohol (PVA) separators were successfully prepared through simple mixing and solvent substitution. Interestingly, the RCM with rich carboxylic groups, not only function as nanofillers that increases the strength properties of the three-dimensional porous network, but also enhances Li⁺ transfer (due to the COO^- and Li⁺ interactions), resulting in outstanding Li⁺ transference number (0.54) of the RCM/PVA separator. In addition, the RCM/PVA separator shows excellent thermal stability and high liquid absorption rate (481.25 %). The LiFePO₄/3 % RCM-HCl/PVA/Li cell displayed a high discharge capacity of 152.6 mAh·g^-1 after 200 cycles at 1C. This work provides a new light on the fabrication of biodegradable separators for LIBs via a novel and cost-effective strategy.