High-Safety Lithium Metal Batteries Enabled by Additive of Fire-Extinguishing Microcapsules

Lithium metal battery (LMB) is regarded as one of the most promising high-energy energy storage systems. However, the high reactivity of lithium metal and the formation of lithium dendrites during battery operation have caused safety concerns. Herein, we present the design and synthesis of fire-extinguishing microcapsules to enhance LMB safety. The encapsulation strategy addressed perfluoro(2-methyl-3-pentanone)'s volatility and storage challenges, yielding microcapsules with stable and uniform size distributions. The rapid release and effective fire-extinguishing performance of the microcapsules upon exposure to high temperatures has been demonstrated. Integration of these microcapsules into LMBs showed no significant impact on electrochemical performance, maintaining high lithium-ion conductivity, and stable cycling capacity. Notably, practical safety tests on pouch cells indicated that the presence of microcapsules effectively prevented ignition and improved thermal stability under mechanical damage and flame intrusion, underscoring their potential for significantly improved battery safety. These findings provide a robust strategy for mitigating fire hazards of high-energy-density battery systems without compromising their electrochemical performances.