Mo10V2@MIL-101: pseudo-capacitive and redox-active efficient anode material for high-rate lithium cluster batteries

Abstract

Efficient anode materials that exhibit superior charge transfer, multi-electron transfer, and reduced volume changes are highly valued in lithium-ion storage. Polyoxometalates (POMs) have been used in various energy storage and conversion devices due to their wide electrochemical features and various redox properties. However, the facile solubility of POM in the electrolyte limits its cycling stability for further use in electrochemical applications. The above-mentioned difficulty can be improved through the encapsulation of POM in metal–organic framework (MOF) matrices. Herein, Mo₁₀V₂@MIL-101 was designed and synthesized via a one-pot solvothermal method. The Mo₁₀V₂@MIL-101 material exhibits a discharge capacity of 725 mA h g⁻¹ at 100 mA g⁻¹ after 100 cycles, which is higher than those of the parent MIL-101(Fe) (328 mA h g⁻¹) and Mo₁₀V₂ (122 mA h g⁻¹). Even at a higher current density of 1000 mA g⁻¹, a high specific capacity of 625 mA h g⁻¹ is attained after 300 cycles. Due to the multi-redox behavior of POM and accessible sites for Li-ion transportation in the MOF, the synergistic effects of these two boost the specific capacity and further reduce the volume expansion. An increasing trend in the discharge capacity arises as a result of pseudo-capacitive behavior. Hence, this work helps to advance the development of novel lithium storage electrode materials based on POM@MOFs.