This review discusses the critical importance of lithium-ion battery (LIB) safety, particularly in the context of increasing energy density and the frequent occurrence of fires and explosions. The authors highlight the need for intrinsic safety solutions and provide an overview of recent advancements in materials design to improve LIB safety. The thermal runaway process, which is the primary cause of battery safety concerns, is divided into three stages: onset of overheating, heat accumulation and gas release, and combustion and explosion. Each stage is addressed with specific strategies, including the development of reliable anode and cathode materials, multifunctional electrolytes and separators, overcharging protection, thermally switchable current collectors, and flame-retardant additives. The review also explores the potential of nonflammable liquid electrolytes and solid-state electrolytes as ultimate solutions for battery safety. Despite significant progress, the authors emphasize the need for further research to develop more efficient methods and well-designed materials to ensure the reliability and safety of high-energy density LIBs.This review discusses the critical importance of lithium-ion battery (LIB) safety, particularly in the context of increasing energy density and the frequent occurrence of fires and explosions. The authors highlight the need for intrinsic safety solutions and provide an overview of recent advancements in materials design to improve LIB safety. The thermal runaway process, which is the primary cause of battery safety concerns, is divided into three stages: onset of overheating, heat accumulation and gas release, and combustion and explosion. Each stage is addressed with specific strategies, including the development of reliable anode and cathode materials, multifunctional electrolytes and separators, overcharging protection, thermally switchable current collectors, and flame-retardant additives. The review also explores the potential of nonflammable liquid electrolytes and solid-state electrolytes as ultimate solutions for battery safety. Despite significant progress, the authors emphasize the need for further research to develop more efficient methods and well-designed materials to ensure the reliability and safety of high-energy density LIBs.