2,2,6,6-Tetramethylpiperidine-1-oxyl-Oxidized Cellulose Nanofiber-Embedded Polymer Electrolytes for All-Solid-State Lithium Metal Batteries

Aseries of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidizedcellulose nanofiber-embedded solid polymer electrolytes were developedby an environmentally friendly one-pot, organic solvent-free manufacturingprocess. Dueto the rapidly increasing demands of lithium-ion batteries,it is imperative to develop separators and even solid-state electrolyteswith high biocompatibility/biodegradability to increase their sustainableeconomic values. In this context, we develop a series of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidizedcellulose nanofiber (TOCN)-embedded solid polymer electrolytes (SPEs)through an environmentally friendly one-pot, organic solvent-freemanufacturing process, for which the natural TOCN acts as a rigid3D skeleton and polyethylene glycol (PEG(3350)) acts as thesoft matrix. Unlike typical inorganic fillers (e.g., Al2O3), the addition of a small amount of TOCN into PEG allowsthe formation of free-standing SPE films. In addition to greatly improvingthe mechanical strength, the introduced TOCN preserves sufficiention transport channels. The optimized free-standing TP28 SPE membranepossesses a decent ionic conductivity of 4.89 x 10(-4) S cm(-1) associated with a t (Li+) value of 0.31 at 80 & DEG;C, a high electrochemical stabilitywindow of >4.0 V, and a high tensile strength of 1.10 MPa. It alsoexhibits effective functionality and compatibility with the Li-metal(Li-symmetric cell cycling over 900 h at 80 & DEG;C) anode and theLiFePO(4) cathode. The assembled all-solid-state LiFePO4|TP28|Li battery delivers great rate capability and cyclingperformance (96.5% after 100 cycles) with an initial capacity of 151mAh g(-1) at 0.1 C at 60 & DEG;C. Our results demonstratethe promising potential of lignocellulosic biomass for fabricatingbiocompatible SPEs for Li-metal batteries that can largely increasetheir sustainable economic values.