Abstract
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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 CuGeO3 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 thusobtained
CuGeO3 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−1 at 100 mA g−1
, 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.