Self-healing electrostatic shield enabling uniform lithium deposition in all-solid-state lithium batteries

Abstract Poly(ethylene oxide) (PEO) based solid polymer electrolytes (SPEs) have been regarded as promising electrolytes for next-generation all-solid-state lithium batteries (ASSLBs). However, they have achieved limited cycling stability due to their inability to suppress Li dendrite growth. Herein, a self-healing electrostatic shield (SHES) is proposed to force uniform lithium deposition by introducing 0.05 M Cs+. At this situation, the Cs+ shows a lower reduction potential compared to the Li+ reduction potential (1.7 M). During lithium deposition, the Cs+ forms a positively charged electrostatic shield around the initial Li tips, which forces further deposition of lithium to adjacent regions of the anode and results in a dendrite-free Li deposition. With this in mind, the Li–Li symmetric cells can operate for 1000 and 500 h at current densities of 0.1 and 0.2 mA cm−2, respectively, which are 10 times longer than Cs+-free PEO electrolyte. Moreover, the Li/PEO-Cs+/LiFePO4 (LFP) cell achieves high capacity retention of 90% within 100 cycles at 0.5C and retains a high capacity of 113 mAh g−1 at 0.8C, while short-circuits are observed for the Li/PEO/LFP cell, even at 0.2C. This strategy will generate substantial interest and shed light on the development of other dendrite-free SPEs and ASSLBs systems.