Enhanced specific energy in fast-charging lithium-ion batteries negative electrodes via Ti-O covalency-mediated low potential

Developing lithium-ion batteries with high specific energy and fast-charging capability requires overcoming the potential-capacity trade-off in negative electrodes. Conventional fast-charging materials (e.g., Li 4 Ti 5 O 12 , TiNb 2 O 7 ) operate at high potentials (>1.5 V vs. Li + /Li) to circumvent lithium plating, yet this compromises specific energy. A viable strategy for enhancing the specific energy is to reduce the potential while avoiding the lithium plating risk; however, the underlying mechanisms remain unclear. Here we demonstrate that enhancing Titanium-Oxygen covalency through pseudo-Jahn-Teller Effect distortion in Ruddlesden-Popper perovskites enables low-potential operation. The Li 2 La 2 Ti 3 O 10 negative electrode exhibits a working potential of 0.5 V vs. Li + /Li with initial 139.3 mAh g −1 at 5 A g −1 and 72.9% capacity retention after 5000 cycles. Full cells with LiNi 0.8 Co 0.1 Mn 0.1 O 2 positive electrodes deliver 3.45 V average discharge voltage-50% higher than conventional Li 4 Ti 5 O 12  | |LiNi 0.8 Co 0.1 Mn 0.1 O 2 systems-achieving 100 mAh g −1 at 4 A g −1 . Mechanistic analysis reveals low Li⁺ migration barriers and stable Ruddlesden-Popper perovskite frameworks enable rapid ion transport.