Solid-State vs. Liquid Electrolytes: A Comparative Review

Abstract

Considering the increasingly stringent safety and energy density requirements of lithium-ion batteries, scientists have focused more on solid-state lithium-ion battery research in recent years. Solid-state electrolytes (SSEs) have emerged as a transformative solution to the intrinsic limitations of conventional liquid electrolytes, particularly in mitigating safety hazards and enhancing energy density for next-generation batteries. This review systematically contrasts the fundamental mechanisms of SSEs and liquid electrolytes, demonstrating how SSEs address critical challenges. Firstly, the superior thermal stability eliminates flammable components, fundamentally preventing thermal runaway chains. Secondly the robust mechanical properties physically suppress lithium dendrite penetration Finally, the extended electrochemical windows enable stable operation with high-voltage/high-capacity electrodes. Despite these advantages, interfacial resistance and high manufacturing costs remain key barriers to large-scale adoption. Future advancements hinge on innovative interface engineering, scalable synthesis of stable SSE materials (e.g., oxygen-doped sulfides), and system-level designs such as bipolar stacking. Emerging applications in multivalent-ion batteries and solid-state lithium-sulfur systems are also discussed as pivotal frontiers for sustainable energy storage.