A groundbreaking collaboration between the Changchun Institute of Applied Chemistry of the Chinese Academy of Sciences and the Institute of Deep-sea Science and Engineering has yielded a high-specific-energy rechargeable lithium battery pack capable of withstanding full-ocean-depth pressure. Boasting an energy density exceeding 400Wh/kg, this battery pack has successfully completed sea trials. This innovative solution addresses the critical issue of energy supply in high-pressure deep-sea environments, enabling lightweight, highly reliable, and long-lasting energy systems for deep-sea equipment.