Introducing Low-Tortuosity Channels in Thick Electrode for High-Areal-Capacity Solid Polymer Battery

Abstract

All-solid-state lithium battery (ASSLB) is the most promising candidate of next generation lithium ion batteries. However, the construction of high loading composite electrode is a bottleneck of ASSLB. Herein, low-tortuosity LiFePO 4 (LFP-LT) composite electrodes with high mass loadings are prepared by a phase inversion and in-situ polymerization method. The in-situ formed polymer electrolyte possesses a wide electrochemical window (0-4.9 V vs. Li + /Li), high lithium-ion transference number (0.73) and a high Li + conductivity (0.23 mS cm -1 ) at room temperature. In addition, the low-tortuosity channels can serve as fast electron/ion pathways. Consequently, the LFP-LT composite electrode with a loading of 15 mg cm -2 shows an excellent cycling stability with a capacity retention of 89.0% after 250 cycles at 1C. Notably, an ultra-high loading LFP-LT composite electrode (35 mg cm -2 ) displays a high areal capacity of 5 mAh cm -2 and an enhanced cycling performance with a capacity retention of 94.0% after 150 cycles at 0.5C. This work presents an efficient strategy to construct low-tortuosity and high loading solid polymer batteries.

Keywords: solid polymer battery, high loading electrode, phase inversion, fast ion/electron pathways, in-situ polymerization