K2M2(MoO4)3 (M = Ni, Co, Mn): Potential anode materials with high Li-ion storage properties and good low-temperature performance

Owing to the stable three-dimensional network structure, suitable working potential, multi-electronic reaction and high electrochemical activity, molybdate is considered to be a potential anode material for lithium-ion batteries (LIBs) with high energy density and excellent temperature adaptability, while its electrochemical reaction mechanism and limiting factors at low temperature are unclear. Here, three molybdate materials K2M2(MoO4)3/C (M = Ni, Co, Mn) are synthesized and firstly used as anode materials for LIBs. The K2Mn2(MoO4)3/C composite delivers a discharge specific capacity of 1263 mAh·g−1 at 50 mA·g−1 and maintains a reversible capacity of 586 mAh·g−1 after 100 cycles. Moreover, the capacities of the K2Co2(MoO4)3/C composite are as high as 935, 896 and 673 mAh·g−1 at 0, −10, and −20 °C, respectively. The ex-situ X-ray diffraction (XRD) is carried out to understand the electrochemical reaction mechanism. In addition, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are also applied to obtain the electrochemical reaction mechanism and limiting factors at low temperature. This work deepens the understanding of the low temperature electrochemical reaction mechanism of molybdate anode materials.