Cellulosic all-solid-state electrolyte for lithium batteries fabricated via bio-synthetic avenue

Abstract

Composite solid electrolytes (CSEs) have been attracting tremendous attention as the revolutionary separators using in the next-generation of lithium battery with high safety and improved electrochemical performance. Nevertheless, the traditional CSEs composed of Li+-conducting polymers and ceramics normally suffer from structural deformation, inhomogeneous integration, and inadequate mechanical strength. Herein, the Li1.5Al0.5Ge1.5(PO4)3 (LAGP) conductive ceramics supported by bacterial cellulose (BC) scaffolds (LAGP@BC) are successfully fabricated as CSEs with the assistance of biosynthesis. After infiltration by polyethylene oxide (PEO), the as-prepared LAGP@BC-PEO presents excellent Young's modulus up to 107.8 MPa. The porous cellulosic architectures encourage homogeneous Li+ flux across the CSEs. The LAGP@BC-PEO exhibits high ion transfer number (0.45) and ionic conductivity (1.01 × 10−4 S cm−1). After assembling LAGP@BC-PEO into a full cell, the Li|LAGP@BC-PEO|LiFePO4 delivers a higher capacity (168.2 mAh g−1) at 1C and superior capacity retention of 90.4% after 200 cycles. This work provides a judicious design for fabricating CSEs by integrating conductive ceramics into BC scaffolds with a green and mild biosynthetic avenue.