An in-situ self-etching enabled high-power electrode for aqueous zinc-ion batteries

Sluggish storage kinetics is considered as the main bottleneck of cathode materials for fast-charging aqueous zinc-ion batteries (AZIBs). In this report, we propose a novel in-situ self-etching strategy to unlock the Palm tree-like vanadium oxide/carbon nanofiber membrane (P-VO/C) as a robust free-standing electrode. Comprehensive investigations including the finite element simulation, in-situ X-ray diffraction, and in-situ electrochemical impedance spectroscopy disclosed it an electrochemically induced phase transformation mechanism from VO to layered ZnxV2O5⋅nH2O, as well as superior storage kinetics with ultrahigh pseudocapacitive contribution. As demonstrated, such electrode can remain a specific capacity of 285 mA h g−1 after 100 cycles at 1 A g−1, 144.4 mA h g−1 after 1500 cycles at 30 A g−1, and even 97 mA h g−1 after 3000 cycles at 60 A g−1, respectively. Unexpectedly, an impressive power density of 78.9 kW kg−1 at the super-high current density of 100 A g−1 also can be achieved. Such design concept of in-situ self-etching free-standing electrode can provide a brand-new insight into extending the pseudocapacitive storage limit, so as to promote the development of high-power energy storage devices including but not limited to AZIBs.