Oxygen-deficient LiV_(3)O_(8) is considered as one of the promising cathode materials for lithium ion batteries(LIBs)because of its high cycling stability and rate capability.However,it is very difficult to control an...Oxygen-deficient LiV_(3)O_(8) is considered as one of the promising cathode materials for lithium ion batteries(LIBs)because of its high cycling stability and rate capability.However,it is very difficult to control and study the content and position of V^(4+)and oxygen vacancies in LiV_(3)O_(8),and therefore the mechanism of improving electrochemical performance of LiV_(3)O_(8) is still unclear.Herein,we developed four LiV_(3)O_(8) nanosheets with different V^(4+)and oxygen vacancy contents and positions.The physicochemical and lithium storage properties indicate that the V^(4+)and oxygen vacancies in the surface layer increase the contribution of pseudocapacitive lithium storage on the nanosheet surface.The V^(4+)and oxygen vacancies in the lattice improve the electrical conductivity of LiV_(3)O_(8),and enhance the phase transformation and lithium ion diffusion rates.By adjusting the content of V^(4+)and oxygen vacancies,we obtained an oxygen-deficient LiV_(3)O_(8) nanosheet which maintained more than 93%of the initial reversible capacity after 300 cycles at 5,000 mA·g^(−1).The V^(4+)and oxygen vacancies play an important role in improving the stability and rapidity of lithium storage.This work is helpful to understand the stable and fast lithium storage mechanism of oxygen-deficient LiV_(3)O_(8),and might lay a foundation for further studies of other oxygen-deficient metal oxide electrodes for long-life and high-power LIBs.展开更多
基金The authors thank for the financial support of Beijing Natural Science Foundation(No.2182015)the National Natural Science Foundation of China(No.21805012).
文摘Oxygen-deficient LiV_(3)O_(8) is considered as one of the promising cathode materials for lithium ion batteries(LIBs)because of its high cycling stability and rate capability.However,it is very difficult to control and study the content and position of V^(4+)and oxygen vacancies in LiV_(3)O_(8),and therefore the mechanism of improving electrochemical performance of LiV_(3)O_(8) is still unclear.Herein,we developed four LiV_(3)O_(8) nanosheets with different V^(4+)and oxygen vacancy contents and positions.The physicochemical and lithium storage properties indicate that the V^(4+)and oxygen vacancies in the surface layer increase the contribution of pseudocapacitive lithium storage on the nanosheet surface.The V^(4+)and oxygen vacancies in the lattice improve the electrical conductivity of LiV_(3)O_(8),and enhance the phase transformation and lithium ion diffusion rates.By adjusting the content of V^(4+)and oxygen vacancies,we obtained an oxygen-deficient LiV_(3)O_(8) nanosheet which maintained more than 93%of the initial reversible capacity after 300 cycles at 5,000 mA·g^(−1).The V^(4+)and oxygen vacancies play an important role in improving the stability and rapidity of lithium storage.This work is helpful to understand the stable and fast lithium storage mechanism of oxygen-deficient LiV_(3)O_(8),and might lay a foundation for further studies of other oxygen-deficient metal oxide electrodes for long-life and high-power LIBs.
