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

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., Li₄Ti₅O₁₂, TiNb₂O₇) 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 Li₂La₂Ti₃O₁₀ 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_0.8Co_0.1Mn_0.1O₂ positive electrodes deliver 3.45 V average discharge voltage-50% higher than conventional Li₄Ti₅O₁₂ | |LiNi_0.8Co_0.1Mn_0.1O₂ 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.