Enhancing interfacial stability in solid-state lithium batteries with polymer/garnet solid electrolyte and composite cathode framework

Abstract

The solid-state lithium battery is considered as an ideal next-generation energy storage device owing to its high safety, high energy density and low cost. However, the poor ionic conductivity of solid electrolyte and low interfacial stability has hindered the application of solid-state lithium battery. Here, a flexible polymer/garnet solid electrolyte is prepared with poly(ethylene oxide), poly(vinylidene fluoride), Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , lithium bis(trifluoromethanesulfonyl)imide and oxalate, which exhibits an ionic conductivity of 2.0 × 10 −4 S cm −1 at 55 °C, improved mechanical property, wide electrochemical window (4.8 V vs. Li/Li + ), enhanced thermal stabilities. Tiny acidic OX was introduced to inhibit the alkalinity reactions between Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 and poly(vinylidene fluoride). In order to improve the interfacial stability between cathode and electrolyte, an Al 2 O 3 @LiNi 0.5 Co 0.2 Mn 0.3 O 2 based composite cathode framework is also fabricated with poly(ethylene oxide) polymer and lithium salt as additives. The solid-state lithium battery assembled with polymer/garnet solid electrolyte and composite cathode framework demonstrates a high initial discharge capacity of 150.6 mAh g −1 and good capacity retention of 86.7% after 80 cycles at 0.2 C and 55 °C, which provides a promising choice for achieving the stable electrode/electrolyte interfacial contact in solid-state lithium batteries. An solid-state lithium metal battery was assembled with polymer/garnet solid electrolyte, composite cathode framework and lithium anode, exhibiting good electrochemical performance and high electrolyte/electrode interfacial stabilities.