Highly stable LiTa2PO8-based hybrid solid electrolytes via the in situ interfacial formation technique for solid-state lithium-metal batteries† Solid-state lithium metal batteries (SSLMBs) that incorporate composite polymer electrolytes have gained significant attention as potential replacements for liquid electrolytes (LEs) in lithium metal batteries (LMBs) due to their exceptional safety, outstanding energy storage performance, and remarkable stability even under high temperature conditions.