A POM@CNT hybrid nanostructure enabling fast kinetics and high capacity in lithium-ion batteries

Abstract

Polyoxometalates (POMs) are promising alternative electrode materials for lithium-ion batteries (LIBs) owing to their redox chemistry and high energy storage potential. However, their practical application is limited by inherent drawbacks such as low electrical conductivity and high solubility in electrolytes. To overcome these challenges, we synthesized a polyoxometalate–carbon nanotube hybrid nanostructure (POM@CNT) by wiring phosphomolybdic acid (PMo) with functionalized carbon nanotubes (CNTs) via electrostatic interactions. Comprehensive structural and electrochemical characterizations confirmed the formation of a stable, conductive hybrid network. The POM@CNT electrode delivers a remarkable initial discharge capacity of 2100 mAh g⁻¹, excellent rate capability and long-term cycling stability over 500 cycles, significantly outperforming electrodes based on PMo or CNTs alone. Electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) analyses revealed that the hybrid structure enables faster charge transfer and enhanced Li⁺ ion diffusion. The superior performance is attributed to the synergistic integration of PMo and CNTs, which promotes rapid electrochemical kinetics. This work highlights the potential of the POMs@CNT hybrid nanostructure as a high-performance and durable electrode material for lithium-ion storage, paving the way for further exploration of electroactive POM clusters in advanced energy storage systems.