Reconstructing Fast Ion Transport Channels of Zn3v2o7 (Oh)2·2h2o to Realize Enhanced Zn2+ Storage Performance

Abstract

Zinc ion batteries attract great attention because of their safety, economy and environmental friendliness. However, the sluggish diffusion kinetics of Zn2+ limit practical application. Here, reconstructed Zn3V2O7 (OH)2·2H2O (ZVO) is prepared by electrochemical in situ conversion and the bridge oxygen vacancy concentration of V–O–V in ZVO is regulated by adjusting conversion conditions to modulate the ion transport channels. The Zn2+ diffusion energy barrier is minimized (0.20 eV) at a bridge oxygen vacancy concentration of 8%, while more oxygen vacancies hinder the transport of Zn2+ since the channel shrink. Thanks to the reconstructed one–dimensional channels with 8% V–O–V bridging oxygen vacancies, the cathode exhibits ultra–high performance of 135 mAh g−1 at 80 A g−1 and long life of 10,000 cycles with an 88% capacity retention at -30°C.

Keywords: bridging oxygen vacancy, electrochemical in situ conversion, ion transport channels, Zn ion batteries