Electrostatic supramolecular self-assembly of vanadium oxide and conductive polymer for highly efficient zinc ion storage

Abstract

Despite the widespread use of lithium-ion batteries (LIBs), the constraints of limited lithium sources and safety concerns persist. Aqueous zinc-ion batteries (ZIBs) are a promising alternative, leveraging abundant resources, non-flammable electrolytes, high safety, and cost-effectiveness. However, challenges remain due to inadequate cathode materials. Layered vanadium oxide (LVO) holds promise but suffers from cyclic stability issues. Introducing conductive polymers into LVO interlayers can enhance structural integrity, prolong lifespan, and increase electronic conductivity simultaneously. Here, we focus on V₁₀O₂₄·nH₂O (VOH) with a large interlayer spacing and utilize the supramolecular self-assembly of poly(3,4-ethylenedioxythiophene) (PEDOT) and VOH to obtain 2D VOH/PEDOT (PVOH) cathodes for ZIBs. Thanks to the reinforced layer structure and a conductive layer of hydrophobic PEDOT coating which reduces vanadium dissolution and promotes electronic conductivity, the optimized PVOH-M exhibits a high capacity of 452.14 mA h g⁻¹ at 100 mA g⁻¹ and a significant energy density of 316.08 Wh kg⁻¹, along with 91.78 % capacity retention after 3000 cycles at 10 A g⁻¹. Density Functional Theory (DFT) calculations further prove the unique three-step self-assembly model and explain the enhanced performances theoretically. This study demonstrates the efficacy of electrostatic supramolecular self-assembly as a strategy in modifying cathodes, offering insights into layered cathode design.