Advanced Composite Solid Electrolyte Architecture Constructed with Amino‐Modified Cellulose and Carbon Nitride via Biosynthetic Avenue

Abstract Polyethylene oxide (PEO) solid electrolytes are regarded as a promising candidate for all‐solid‐state lithium batteries owing to their high safety and interfacial compatibility. However, PEO electrolyte is plagued by relatively weak structural strength and unsatisfactory Li + conductivity. Herein, a mechanically strong and Li + conductively favorable cellulosic scaffold of PEO is fabricated through amino (‐NH 2 ) modification and g‐C 3 N 4 (CN) incorporation of bacterial cellulose (BC) under a microbial circumstance. The biologically ‐NH 2 modified BC (B‐NBC) is entangled with CN nanosheets (CN@B‐NBC) through an in situ secretion of nanocellulose followed by hydrogen bond‐induced self‐assembly. The ‐NH 2 groups from B‐NBC weaken the complexation of Li + with its counterpart, thus facilitating the release of more free Li + . CN with strong C‐N covalence and extra lone electrons of N further strengthens the BC skeleton and meanwhile offers sufficient anchors for Li + migration. After infiltrating by LiTFSI/PEO (LP), the LP/CN@B‐NBC composite solid electrolyte (CSE) exhibits high lithium transference number and ionic conductivity. Upon coupling with LiFePO 4 cathode, the full battery exhibits a remarkably high specific capacity, superior rate capability, and decent cycling stability. This work pioneers the attempts of chemical decoration and ingredient incorporation of BC architecture in CSE with the aid of a bottom‐up biosynthetic avenue.