Investigation of the Enhanced Lithium Battery Storage in a Polyoxometalate Model: From Solid Spheres to Hollow Balls

Abstract Materials with hollow structures are generally considered more conducive to lithium‐ion storage than solid materials, but there is no suitable crystal model system to illustrate it. Herein, it is successfully simulated by utilizing polyoxometalate models to compare the lithium‐ion battery performances. New crystals, EMI‐PMo₁₂ (EMI: 1‐ethyl‐3‐methylimidazolium) with solid sphere and EMI‐Mo₇₂V₃₀ and EMI‐Mo₁₃₂ with hollow structures, are synthesized. In order to increase their electronic conductivity, the composites EMI‐PMo₁₂@rGO, EMI‐Mo₇₂V₃₀@rGO, and EMI‐Mo₁₃₂@rGO (rGO: reduced graphene oxide) can be prepared by introducing rGO. The composite EMI‐Mo₇₂V₃₀@rGO delivers a reversible capacity of 1145 mAh g⁻¹ at 100 mA g⁻¹, and the capacity retentions are nearly 100% at 2000 mA g⁻¹ for over 500 cycles. This study not only provides a promising avenue toward manufacturing and developing new‐generation electrode materials in lithium‐ion storage but also proposes a mechanism toward comparing their performances at the molecular level.