The ternary composite formed by intercalation of porous Keggin-type POM and lamellar MoS2 into accordion-like MXene for enhanced electrochemical properties of the LIBs

Keggin-type polyoxometalate (POM) is a new pseudocapacitive material with advanced multi-electron conduction capability, good mechanical and thermal stability. However, owing to the limited specific interfacial area and inferior conductivity of POMs, it is difficult to exert its excellent redox properties as an electrode material alone. In an effort to overcome these limitations, a heterostructured material MnPMo8V6@MXene/MoS2 was developed using a combination of hydrothermal method and electrostatic adsorption, leveraging the synergistic self-assembly of multiple substances. The morphology and sufficient structural characterization reveal that Keggin POM and MoS2 were homogeneously anchored on the accordion-like MXene leading to a triaryl composite. The resulting composites demonstrate improved overall performance and more efficient ion/electron transport capacity as anode materials for LIBs compared to single-component and binary materials. Typically, the compound presented a superior reversible capacity of 1061.3 mA h g- 1 at 0.1 A g-1, a high capacitance retention of 851.1 mA h g- 1 after 300 cycles, and a prominent rate capacity of 450.3 mA h g- 1 at 2.0 A g-1, which surpasses the performance of most reported anodes for LIBs. Kinetic calculations also indicate that the charge accumulation functionality of MnPMo8V6@MXene/MoS2 involves diffusion and pseudocapacitive behavior. This study combines the outstanding Faraday properties of Keggin POM, the mechanical strength of MoS2 and the ultra-high conductivity, low impedance and high specific surface area of accordion-like MXene into the ternary composite. Meanwhile, a unique 3-D conductive network is formed among POM with regular channels, MoS2 nanosheets and accordion-like MXene. The complementary performance and favorable morphology make the three components produce perfect synergistic effect and outstanding comprehensive lithium-ion batteries performance.