Mg2+ Initiated in-situ Polymerization of Dioxolane Enabling Stable Interfaces in Solid-State Lithium Metal Batteries

Abstract

In situ polymerized solid-state polymer electrolytes (SPEs) have attracted much attention due to their good machinability and excellent interface contact with electrodes. However, the undesirable stability to lithium metal and high-voltage electrodes hinders their application in high energy density solid-state lithium batteries. Herein, a poly(1,3-dioxolane) composite SPE possessing high interfacial stability with both lithium metal anode and high voltage cathode was fabricated via in-situ polymerization initiated by a Mg2+-containing montmorillonite filler. The strong coordination between Mg2+ and anions of lithium salts not only improves the antioxidant stability of the polymer chains, but also optimizes the lithium ion coordination structure and constructs robust MgF2-containing interphases on both anode and cathode. As a result, the composite SPE exhibits an improved homogeneous polymer chain distribution, a high lithium-ion transference number of 0.60 and an extended electrochemical window of 5.3 V. The Li/Li symmetric cells exhibit outstanding cycling stability for 6000 hours and the Li/LiNi0.8Co0.1Mn0.1O2 cells demonstrate excellent rate capability and cycle stability over 500 cycles. This work provides a promising pathway for the SPEs toward practical high energy density solid-state batteries.