Polymer electrolytes shielded by 2D Li0.46Mn0.77PS3 Li+-conductors for all-solid-state lithium-metal batteries

The development of solid polymer electrolytes (SPEs) is impeded by the severe Li-dendrites growth at the unstable SPE-Li interface. Herein, we demonstrate that the interfacial stability of poly(ethylene oxide) (PEO) electrolytes against Li metal is significantly improved by a shielding strategy, where the nanosheets of a 2D Li+ conductor Li0.46Mn0.77PS3 (LiMPS) serve as nanosized shields to armor PEO against the spears - lithium dendrites. Besides physical inhibition, LiMPS also homogenizes Li+ flux owing to its 2D nature, superior Li+ conductivity (2.1 × 10−4 S cm−1 at 30 ℃) and strong adsorption of Li+. This strategy also enables PEO-LiMPS electrolytes to exhibit superior ionic conductivity of 2.6 × 10−4 S cm−1 at 45 ℃, a nearly tenfold increase compared to bare PEO electrolytes. Furthermore, the electrochemical stability window (ESW) of PEO-LiMPS electrolytes is expanded to 4.8 V (3.8 V for pristine PEO). As a result, symmetric Li/PEO-LiMPS/Li cells deliver short circuit-free cycling over 600 h, and LiNi0.8Co0.1Mn0.1O2/PEO-LiMPS/Li batteries also present a high-capacity retention over 80% after 200 cycles at 0.2 C. In addition, LFP/PEO-LiMPS/Li pouch cell retains 93% of the initial capacity after cycling at 0.2 C for 230 cycles. This 2D Li+-conductive shielding strategy provides a unique protective mechanism for SPEs in solid-state Li metal batteries (SSLMBs).