A Self-Healable Sulfide/Polymer Composite Electrolyte for Long-Life, Low-Lithium-Excess Lithium-Metal Batteries

Solid electrolyte-protected lithium-metal anodes promise energy-dense, safe cells. While sulfide solid electrolytes enable facile processability and fast ion transport, they suffer from complex chemo-mechanical issues, including Li plating-induced fracture and Li stripping-induced contact loss. To address these issues, a grafting approach is implemented to functionalize the sulfide solid electrolyte (Li3,85Sn0.85Sb0.15S4) with a self-healing unit. This leads to a dynamic bonding between the solid electrolyte network and a mechanically robust polymer scaffold, which reversibly accommodates the volume changes of the lithium-metal anode. Moreover, the approach improves the interfacial contact between the lithium-metal anode and the composite electrolyte, enabling stable cycling at a mild stack pressure (160 kPa). With a negative to positive capacity ratio equals to 1, pouch full cells with a high-nickel cathode (nickel content > 90%) and lithium-metal anode display 92% capacity retention for 140 cycles. Engineering the interface between solid electrolyte and the polymeric binder offers a promising pathway to address the chemo-mechanical issues.

Automated summary

By grafting a self-healing unit onto sulfide solid electrolytes, a dynamic bonding is achieved between the electrolyte network and a strong polymer scaffold, allowing for reversible accommodation of lithium-metal anode volume changes. This approach also enhances interfacial contact between the anode and composite electrolyte, leading to stable cycling and high capacity retention in high-nickel cathode and lithium-metal anode pouch cells. Engineering the interface between solid electrolyte and polymeric binder shows promise in addressing chemo-mechanical issues.