Study on low-temperature performances of Nb16W5O55 anode for lithium-ion batteries

Niobium tungsten oxide Nb16W5O55 is a competitive anode for lithium-ion batteries, while seldom research on low-temperature electrochemical properties. In this paper, Nb16W5O55 is synthesized by solid phase reaction and the effects of operation temperature (25, 0 and - 20 degrees C) on the coulombic efficiency, cycling stability, rate capacity and crystal structure are studied in detail. At 25 degrees C, Nb16W5O55 electrode can give good cycling stability of 184 mAh g(-1) after 404 cycles and rate capacity of 101 mAh g(-1) at 4000 mA g(-1). By contrast, the electrochemical properties decrease obviously at subambient temperatures. Electrochemical impedance spectroscopy reveal that the sharp increase of the charge-transfer impedance and the decrease of the solid-phase Li' diffusion coefficient are the essential factors leading to the deterioration of low temperature performances. However, the low temperature mainly affects specific capacities and rate performances, but has little effect on cyclic stability and crystal structure of Nb16W5O55 electrode, indicated by ex-situ X-ray diffraction analysis. These results provide some new insights for the practical application of Nb16W5O55 anode.