Synergistic nanostructure and heterointerface design propelled ultra-efficient in-situ self-transformation of zinc-ion battery cathodes with favorable kinetics

In-situ self-transformation is proved to be an effective strategy to design high-performance cathodes for aqueous zinc-ion batteries (ZIBs). However, the inferior transformation efficiencies during phase transition limit its further application. Herein, a 3D spongy VO₂-graphene (VO₂-rG) precursor has been designed for achieving the ultra-efficient in-situ self-transformation process from VO₂-rG into multifaceted V₂O₅·nH₂O-graphene composite (VOH-rG). Benefiting from the highly conductive heterointerfaces, rich reaction sites and numerous ions diffusion channels of VO₂-rG, almost 100% VO₂ nanobelts are converted into VOH during the first charging with few side reactions, indicating a highly efficient transformation kinetics. This strategy enables structural modulation from micro-nano level to molecular level by integrating pre-inserted H₂O molecules and constructing 3D porous heterogeneous architecture into the VOH-rG cathode simultaneously, leading to fast and enduring Zn²⁺ (de)intercalation kinetics. Consequently, the VOH-rG cathode exhibits high capacity of 466 mA h g⁻¹ at 0.1 A g⁻¹, superior rate performance (190 mA h g⁻¹ even at 20 A g⁻¹) and excellent cycling stability with 100% capacity retention over 5000 cycles. Moreover, the assembled VOH-rG//Zn flexible quasi-solid-state batteries also present impressive performance. Such an ultra-efficient in-situ self-transformation strategy would pave a new way to explore promising electrode materials for advanced energy storage.