Silicon-containing polycarbonate composite solid electrolyte with enhanced interfacial stability for lithium metal batteries

Abstract

Although polyvinylidene carbonate (PVCA)-based solid polymer electrolyte (SPE) offers advantages of easy curing and high ionic conductivity , its highly flexible polymer chain segments lead to poor mechanical properties and interfacial incompatibility with electrodes, restricting the practical applications in high-energy-density batteries . In this work, a silicon-containing PVCA composite solid electrolyte (S-PVCA) is constructed using a polyacrylonitrile/Li 1.2 Ca 0.1 Zr 1.9 (PO 4 ) 3 electrospun fiber membrane as backbone. The ionic conductivity of S-PVCA reaches 3.2 × 10 -4 S cm -1 with a Li-ion transference number of 0.66. The high dielectric constant of PVCA segments significantly suppresses the growth of lithium dendrites , allowing Li||Li symmetric cells to maintain low polarization over an extended cycling period of 1100 h. Furthermore, the S-PVCA demonstrates good electrolyte/electrode interfacial stability due to the formation of stable chemical bonds by in-situ reaction of vinyltriethoxysilane monomer with electrodes. Consequently, the S-PVCA assembled Li||LiFePO 4 half cell exhibits good cycle stability, achieving a capacity retention rate of 83 % after 400 cycles at a 0.5C rate, compared to 67 % for the PVCA cell. Additionally, the Li||LiFePO 4 full cell using S-PVCA electrolyte (N/P ratio: 2.8) keeps almost the same discharge capacity as the initial state after 90 cycles at 0.5C. Notably, the Li||LiFePO 4 pouch cell continues to operate effectively under folding and cutting conditions. When the working voltage is elevated to 4.2 V, the Li||LiNi 0.6 Mn 0.2 Co 0.2 O 2 cell maintains 84 % of its initial capacity after 100 cycles. This work presents a design concept that incorporates ceramic particles to reinforce polycarbonate-based SPE, addressing the trade-off between mechanical strength and electrochemical performance of electrolyte. Therefore, this research enriches the landscape of polymer electrolytes and fosters the vigorous development of high-energy-density lithium metal batteries .

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