Energy storage batteries are crucial for the stable utilization of renewable energy, but their cycle life and rate performance still need improvement. Lithium-free cathode materials offer significant advantages, yet when paired with conventional graphite anodes, they cannot function properly due to the absence of active lithium ions. Recently, the Gao Yue team at Fudan University published an article titled “Long-Lifespan and High-Rate Energy Storage Enabled by Lithium-Free Batteries with External Li Supply” in the internationally renowned journal Advanced Materials. The paper systematically explores the conditions and influencing factors required for external lithium supplementation in lithium-free batteries, providing a feasible strategy for grid-scale energy storage applications.

The study delves into the application challenges of lithium-free cathode materials in lithium-ion battery systems and achieves a breakthrough in long-cycle-life and high-rate performance of lithium-free batteries through external lithium supply. Traditional prelithiation additives suffer from issues such as excessively high decomposition voltages, incomplete electrochemical conversion, and residual solid byproducts. This research innovatively uses lithium trifluoromethanesulfonate (LiSO₂CF₃) as an electrolyte additive in graphite|TiS₂ pouch cells. The additive undergoes stable electrochemical decomposition at 3.8V, supplying lithium ions to the system without generating any solid residues after decomposition, effectively solving the problem of byproduct accumulation and benefiting long-term stable battery operation.

Electrode structural integrity is critical for long-term stable cycling of batteries. Conventional cathode prelithiation additives often disrupt the electrode conductive network, while anode prelithiation agents can compromise electrode integrity. In this study, LiSO₂CF₃ is introduced as an electrolyte additive. Electron microscopy and ultrasonic imaging analyses confirm that the lithium supplementation process causes no damage to the electrode structure.

The composition of the electrode interface is another key factor determining long-cycle stability. X-ray photoelectron spectroscopy (XPS) analysis conducted by the team shows that the external lithium supply process does not trigger additional side reactions on the cathode side, and the released lithium ions successfully intercalate into the graphite anode, providing active lithium for battery cycling.

The external lithium supply strategy based on LiSO₂CF₃ enables the graphite|TiS₂ pouch cell to achieve over 14,000 cycles at a high current density of 10C, fully meeting the multiple requirements of grid-scale energy storage for fast response, long lifespan, and low operating costs. This work not only provides a practical technical pathway for the development of lithium-free batteries but also opens up a new direction for building green, economical, and efficient energy storage systems.

Gao Yue is a professor at Fudan University, Chief Young Scientist of the National Key R&D Program, and recipient of the Overseas Excellent Young Scientist Award. He received his Ph.D. from Pennsylvania State University in the United States in 2018 and joined the Department of Polymer Science at Fudan University in December 2020. He has conducted a series of innovative studies in the field of regulating battery electrochemical processes using organic and polymer materials, leading multiple projects funded by the National Natural Science Foundation of China and receiving numerous honors.