Abstract Solid-state composite polymer electrolytes (CPEs) are promising for solving the safety problem of lithium metal batteries. However, the CPEs with comparable thickness (10 μm), improved ion conductivities and excellent mechanical strength are great challenges. In the present study, ultrathin (9.6 μm), flexible, mechanically strong, and sandwiched structure solid-state electrolytes (SSEs) are fabricated by a tape casting process, involving the 75 wt % LLTO/PVDF-CPE (LLTO-75) layer designed as intermediate layer sandwiched by two 15 wt % LLTO/PVDF-CPE (LLTO-15) layers. The LLTO-15 is a soft, stable layer on upper and lower sides that could create excellent interfacial contact with electrodes, and LLTO-75 possesses physical rigidity that could inhibit the Li dendrites growth. The balancing between the excellent interfacial contact of LLTO-15 and the inhibition of lithium dendrites growth of LLTO-75 gives sandwiched SSE a high ionic conductivity (4.7 × 10-4 S cm-1) at room temperature, an excellent mechanical strength (7.2 MPa), and uniform Li plating/stripping. When coupled with LiFePO4 and Li metal, the battery assembled with sandwiched SSE maintains 91.7% of its capacity and 99.7% of the Coulombic efficiency, after 1000 cycles. Our study suggests that the proposed sandwiched structure SSE is one of the alternatives for high performance solid-state LMBs.

中文翻译：

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用于固态锂电池的超薄柔性夹层结构复合聚合物电解质膜

摘要 固态复合聚合物电解质（CPEs）有望解决锂金属电池的安全问题。然而，具有可比厚度（10 μm）、改进的离子电导率和优异的机械强度的 CPE 是巨大的挑战。在本研究中，超薄（9.6 μm）、柔性、机械强度高、夹层结构的固态电解质（SSE）是通过流延工艺制造的，涉及 75 wt% LLTO/PVDF-CPE（LLTO-75）层设计为夹在两个 15 wt% LLTO/PVDF-CPE (LLTO-15) 层之间的中间层。LLTO-15 是上下两侧柔软、稳定的层，可以与电极形成良好的界面接触，而 LLTO-75 具有物理刚性，可以抑制锂枝晶的生长。LLTO-15 优异的界面接触与 LLTO-75 对锂枝晶生长的抑制之间的平衡使夹心 SSE 在室温下具有高离子电导率 (4.7 × 10-4 S cm-1)、优异的机械强度 (7.2 MPa)，以及均匀的锂电镀/剥离。当与 LiFePO4 和 Li 金属结合使用时，夹层 SSE 组装的电池在 1000 次循环后仍保持其容量的 91.7% 和库仑效率的 99.7%。我们的研究表明，所提出的夹层结构 SSE 是高性能固态 LMB 的替代品之一。用夹层SSE组装的电池在1000次循环后仍保持其容量的91.7%和库仑效率的99.7%。我们的研究表明，所提出的夹层结构 SSE 是高性能固态 LMB 的替代品之一。用夹层SSE组装的电池在1000次循环后仍保持其容量的91.7%和库仑效率的99.7%。我们的研究表明，所提出的夹层结构 SSE 是高性能固态 LMB 的替代品之一。