LPEO enhanced LAGP composite solid electrolytes for lithium metal batteries

Abstract

The application of solid electrolyte is expected to realize the commercialization of high energy density lithium metal batteries (LMBs). While the interfacial contact between solid inorganic electrolyte and electrodes has become a stumbling block for achieving stable cycling in LMBs. In this work, a Li-containing polyethylene oxide (LPEO) was introduced between LAGP and electrodes as a buffer layer to regulate the interfacial compatibility and reduce interfacial impedance, inhibiting the side reactions. Moreover, ether-oxygen bond on LPEO chain can coordinate with Li⁺ and guide the transportation of Li⁺, achieving fast Li⁺ diffusion between Li_1+xAl_xGe_2-x(PO₄)₃ (LAGP) and electrodes. Specifically, the growth of lithium dendrites is effectively suppressed in LAGP with LPEO modification, which would lead to remarkable cycling stability and rate capability. Therefore, the Li|LPEO-LAGP|Li battery can cycle stably for more than 600 h at 0.1 mA cm⁻². In addition, long-term performance of Li|LPEO-LAGP| LiFePO₄ (LFP) battery was achieved at a rate of 0.4 C, and capacity retention is more than 74% after 200 cycles. The Li|LPEO-LAGP|LiNi_0.8Co_0.1Mn_0.1O₂ also realized the steady operation in the voltage range of 2.8–4.3 V.