Self-healing supramolecular cathode binder additive with dynamic bonds for durable high-voltage solid-state lithium batteries

Ni-rich layered oxide cathodes are indispensable for high-energy polymer-based solid-state lithium metal batteries (SSLMBs), yet their application is plagued by severe volumetric strain and unstable cathode/electrolyte interphases under high cut-off voltages, resulting in rapid capacity fading. Here, a self-healing supramolecular binder additive that integrates dynamic covalent disulfide bonds was proposed to offer exceptional elasticity (> 2300% strain) and rapid room-temperature self-recovery. Operando optical fiber sensing confirms that this adaptive network effectively buffers lattice stress and autonomously repairs interfacial damage, thereby preserving particle–particle contact and continuous Li⁺ conduction. Moreover, electrochemical activation of disulfide bonds generates a sulfur-rich, compact cathode electrolyte interphase (CEI), which suppresses transition-metal dissolution and interfacial side reactions. Benefiting from these dual functions, Li||LiNi_0·83Co_0·12Mn_0·05O₂ (Ni83) cells exhibit 80% capacity retention after 900 cycles at 4.3 V and 2 C, far outperforming PVDF control. SSLMB pouch cells with ultrathin Li and high-loading Ni83 cathodes deliver 357 Wh kg⁻¹, while lean-electrolyte 3 Ah Gr-SiO||LiNi_0·8Co_0·1Mn_0·1O₂ (NCM811) cells achieve 258 Wh kg⁻¹ and 82.6% retention over 500 cycles. This work establishes a mechanically adaptive and self-healing binder design that addresses the coupled mechanical and interfacial instabilities of high-voltage cathodes, offering a practical pathway toward durable, high-energy SSLMBs.