Modulating vacancies concentration ratio of cationic and anionic in WO3 for driving high performance magnesium ions storage

Key Words:BATTERY; ANODE; NANOSHEETS; CARBON

Abstract:Vacancy engineering is an efficient strategy for optimizing the electrochemical performance of electrodes for energy storage devices. However, it is still a challenge for modulating the concentration ratio of cationic va-cancies and anionic vacancies in the electrode via a simple method for enhancing the electrochemical perfor-mance. Herein, cationic (W) vacancies and anionic (O) vacancies are constructed in WO3 simultaneously, and the concentration ratio of W and O vacancies is modulated by adding ious content of glucose to regulate the W vacancies concentration via at a fixed O vacancies concentration. The characterization and DFT results confirm that moderate concentration ratio of W and O vacancies would not only expose more active sites, enhance the electronic conductivity and electrostatic potential, but also inhibit the vacancies gathering to maintain structural stability. In addition, the O--O bonding induced via moderate content of W vacancies owns rich-anionic environment to adsorb more Mg2 as well as reduces electrostatic repulsive-force between Mg2 and cationic lattice to facilitate Mg2 diffusion. Therefore, the moderate concentration ratio of W and O vacancies make VW-O/WO3-1.0 cathode achieve high specific capacity of about 100 mAh g- 1 at 50 mA g- 1, excellent rate capacity of 37.7 mAh g- 1 at 500 mA g- 1 and ultralong cycling life about 1500 cycles. These findings raise the possibility for designing advanced electrodes through vacancy species and controllable concentration engineering.

Volume:57

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Translation or Not:no