The effect of vinylene carbonate additive in polyacrylate-based polymer electrolytes for high-voltage lithium metal batteries

Solid polymer electrolytes (SPEs) have attracted significant attentions for solid-state lithium metal batteries (LMBs) with high energy density and enhanced safety for future applications Herein, we develop a SPE based on a polyacrylate (PEA) polymer matrix and the vinylene carbonate (VC) additive (defined as PEA-VC) for high-voltage solid-state LMBs. We show that introducing VC additive in the PEA-based SPE leads to a high lithium-ion conductivity (1.57 mS/cm at room temperature), a high lithium-ion transference number (0.73), and a wide electrochemical stability window (up to 4.9 V (vs. Li⁺/Li)). The remarkable compatibility of PEA-VC SPE with Li metal and high voltage cathodes was demonstrated in Li//Li symmetric cells (800 h lifetime at current density of 0.1 mA/cm² at RT) and Li//NMC811 full cells (with a capacity retention of 77.8% after 100 cycles at 0.2 C). The improved stability is attributed to the introduction of VC additive, which helps to formulate a robust cathode-electrolyte interphase and thus effectively suppresses the parasitic interface side reactions. Overall, this study reveals the effect of VC additives in high-voltage and solid-state lithium metal batteries, which also offers a general but effective approach for resolving interfacial instability through the additive-engineering strategy.