Exploring Lithium Storage Mechanism and Cycling Stability of Bi2Mo3O12 Binary Metal Oxide Anode Composited with Ti3C2 MXene

Abstract

AbstractMetal oxides are widely evaluated as high‐capacity anode candidates for practical lithium ion battery applications, owing to their attractive volumetric and gravimetric capacities compared with the traditional graphite anode. Synergistic effects on improving electrochemical performance of binary metal oxide anodes have been increasingly reported via different working mechanisms for lithium storage instead of simple combination of two single components. Herein, we report on exploring lithium storage mechanism in Bi2Mo3O12 binary metal oxide for the first time as an anode material. In‐situ synchrotron X‐ray diffraction measurements are performed on this exotic material to elucidate lithium storage behaviors, coupled with voltage‐resolved cyclic voltammetry and ex‐situ X‐ray photoelectron spectroscopy analyses. The Bi2Mo3O12 anode undergoes an irreversible initial conversion reaction, resulting in metallic Bi and Li2MoO4 components through electrochemical lithiation. During successive cycling, these two components reversibly uptake and release Li ions through alloying/de‐alloying and intercalation/de‐intercalation reactions, by forming corresponding Li3Bi alloy and excessively‐lithiated Li2+xMoO4 derivative, respectively. Cycling stability of the Bi2Mo3O12 anode material is considerably enhanced by in‐situ composition with Ti3C2‐based MXene nanosheets. The Bi2Mo3O12@Ti3C2 composite anode material can deliver an initial charge capacity of approximately 846 mAh g−1 at 50 mA g−1 and retain at 227 mAh g−1 upon prolonged 1000 cycles at 2.5 A g−1 high charge/discharge current density. This work offers some insights into lithium storage mechanism and composite nanostructure design in Bi−Mo−O binary metal oxide anode towards enhanced electrochemical performance.