Due to its high security and capacity, titanium niobium oxide (TNO) has gained much attention as anode material for lithium-ion batteries. Yet, its electronic conductivity is too low to have high capability at high rates.
In order to improve the high-rate performance of TNO effectively, a team of researchers from Chengdu Development Center of Science and Technology, China Academy of Engineering Physics, has combined utilized crystal structure modification, particle size reduction, porous structure, and conductive-phase compositing to solve this problem. The electrochemical performance, especially high-rate performance, of the material was significantly enhanced.
The morphology image and rate capability of TNOx/HRGO, it can be seen that its structure is TNOx microspheres wrapped by gossamer-like HRGO, and its capacity is as high as 225 mAh/g and 173 mAh/g at 20 C and 40 C, respectively.
Ti2Nb10O29-x/HRGO hybrid was successfully fabricated by introducing vacancies into Ti2Nb10O29 (TNO) and hybridizing TNO with holey reduced graphene oxide. The structure of TNOx/HRGO is TNOx microspheres with oxygen vacancies wrapped by gossamer-like HRGO. Electrochemical measurements confirmed that TNOx/HRGO hybrid exhibited excellent reversible capacity of 316 mAh/g, 278 mAh/g, 242 mAh/g, 225 mAh/g, and 173 mAh/g at 1 C, 5 C, 10 C, 20 C, and 40 C, respectively. After 300 cycles at 10 C, it still has a high capacity of 238 mAh/g with a high capacity retention of 98%, revealing excellent cycling stability.
The oxygen vacancies of TNOx and the high conductivity of HRGO can effectively enhance the electronic conductivity of the TNOx/HRGO hybrid, and the HRGO holes are beneficial for the transmission of lithium-ion (Li+). The synergy effect of above features improves the rate performance of the TNOx/HRGO hybrid. In addition, the existence of HRGO can buffer volume expansion during the insertion processes of Li+, which can improve cyclic stability of the TNOx/HRGO hybrid.
In this paper, combined utilization of several methods is proved to be an effective way to improve the electrochemical performance of TNO. Ti2Nb10O29-x/HRGO hybrid can be a potential anode material for lithium-ion storage with high security and high capacity, as well as excellent high-rate and cycle performance.
Read the original article on World Scientific Publishing.