By scrutinizing the energy storage process in Li-ion batteries, tuning Li-ion migration behavior by atomic level tailoring will unlock great potential for pursuing higher electrochemical performance. Vacancy, which can effectively modulate the electrical ordering on the nanoscale, even in tiny concentrations, will provide tempting opportunities for manipulating Li-ion migratory behavior. Herein, taking CuGeO as a model, oxygen vacancies obtained by reducing the thickness dimension down to the atomic scale are introduced in this work. As the Li-ion storage progresses, the imbalanced charge distribution emerging around the oxygen vacancies could induce a local built-in electric field, which will accelerate the ions' migration rate by Coulomb forces and thus have benefits for high-rate performance. Furthermore, the thus-obtained CuGeO ultrathin nanosheets (CGOUNs)/graphene van der Waals heterojunctions are used as anodes in Li-ion batteries, which deliver a reversible specific capacity of 1295 mAh g at 100 mA g, with improved rate capability and cycling performance compared to their bulk counterpart. Our findings build a clear connection between the atomic/defect/electronic structure and intrinsic properties for designing high-efficiency electrode materials.

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Summary A thermal model considering effects of the state of charge (SOC) and temperature on heat generation is developed for lithium‐ion (Li‐ion) batteries, which models the ohmic resistance, polarization resistance, and entropy change. This model describes a coupling relationship between heat generation and temperature distribution and can be implemented in real time. Then, the thermal model is applied to predict thermal evolutions of an NCR 18650B Li‐ion battery at different ambient temperatures and discharge rates. Extensive experiments are conducted and illustrate that the proposed model can accurately capture the thermal behavior at different ambient temperatures and discharge rates, with an average error of 1.18°C. In addition, comparative studies show that this model significantly outperforms its two counterparts, namely a constant resistance‐based thermal model and a model whose heat generation depends on the temperature but not the SOC.