Researchers from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) and Yanshan University developed a high-rate anode material for lithium ion battery (LIB). The results were published in Advanced Materials.
Niobium pentoxide (Nb2O5) possesses a high specific capacity and fast Li storage kinetics in a safe operating potential window, which is suitable for high-rate battery systems. H-Nb2O5 exhibits the highest specific capacity of more than 250 mAh/g (1.0~3.0 V vs Li+/Li) among most configurations of Nb2O5.
However, the crystal structure of H-Nb2O5 would change during Li+ (de)intercalation, accompanied with the generation of certain irreversible and inactive phase. That is the main hinderance of H-Nb2O5 anodes in practical applications for LIBs.
The scientists in DICP found that optimizing homogeneity of electron and Li-ion transports surrounding the crystals could improve the capacity and cycling life at high rates.
They introduced an amorphous N-doped carbon layer on the micrometer single-crystal H-Nb2O5 particle (N-C@MSC-Nb2O5) to optimize the homogeneity of phase transition and to suppress the irreversible structure changes.
N-C@MSC-Nb2O5 exhibited a long cycling life of over 1000 charge/discharge cycles at a high current density of 2000 mA/g, 10 times longer than that of pristine H-Nb2O5.
Moreover, N-C@MSC-Nb2O5 also showed a better rate performance than Li4Ti5O12-based and other Nb2O5-based anode materials. In addition, the inherent principle is further conformed via operando transmission electron microscopy (TEM) and X-ray diffraction (XRD).
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