In-situ electrochemical etching of V4AlC3 MAX to V2O5/C composite as Zn-ion storage host

Although V2O5 is considered as promising cathode for aqueous Zn-ion batteries (AZIBs), the poor intrinsic conductivity and unstable structure can significantly hamper its electrochemical energy storage capability. In this work, an in-situ formation strategy of V2O5/C composite nanosheets-derived from V4AlC3 MAX is reported, as an efficient Zn2+ storage host via electrochemically etching-induced phase transition strategy. And the mechanism behind the V4AlC3 MAX electrode conversion were systematically studied. The results revealed that the V-Al bond and Al 1s peak of V4AlC3 were gradually disappearing at prolonged cycling, meanwhile the high valence state vanadium was formed simultaneously as the V2O5/C composite. Benefiting from the efficient reaction kinetics endowed by the V2O5/C nanosheets, such V4AlC3 MAX derived electrode can deliver a high specific capacity of 102 mA h g−1 (20 A/g) at the cut-off voltage of 2.0 V, Furthermore, discharge capacity of 158 mA h g−1 after 3000 cycles at 10 A/g can be retained, confirming it a superior rate capability and cycling stability. The work demonstrates an effective strategy for green and advanced cathode material design and high-performance AZIBs.