Morphology Control and Suppression of Lithium Dendrite Growth in Solid-State Electrolytes Based on Phase-Field Simulation

The safety concerns regarding the flammability and explosivity of traditional liquid electrolyte (LE) lithium batteries have spurred the development of all-solid-state lithium batteries with solid-state electrolytes (SSE). However, the issue of lithium dendrite growth remains a critical challenge to be urgently addressed to commercialize solid-state lithium batteries. Hence, a thorough investigation of the morphology control mechanisms and suppression strategies for lithium dendrite growth within solid-state electrolytes is crucial for improving the cycle life of solid-state lithium batteries and promoting their widespread application. Based on the phase-field method, a multi-physical fields coupling model integrating mechanics and electrochemistry, was constructed to dynamically demonstrate the morphology and mechanical behavior of lithium dendrite growth. Then the model parameters and different conditions were explored to regulate and suppress the morphology of lithium dendrite. The results indicate that, a low-level interfacial reaction rate coefficient can effectively slow down the growth rate of lithium dendrite, while also significantly narrowing the high mechanical stress range at the dendrite root. With the change of the lithium-ion anisotropic diffusion degree within solid-state electrolyte materials, the transition of dendrite morphology from fibrous to flat can be achieved. The polycrystalline nucleation exhibits inhibitory effects on the lateral branches close to each other, with the maximum stress being 3 to 5 times higher than that of single-crystal nucleation. Solid-state electrolytes with a high elastic modulus exert notable mechanical inhibitory effects on lithium dendrite growth. This work can serve as a valuable reference for the optimization design of solid-state electrolytes to suppress dendrite growth in solid-state lithium metal batteries.