Researchers from Chengdu Development Center of Science and Technology have significantly enhanced the performance of titanium niobium oxides for lithium-ion batteries. This has applications in electric vehicles and mobile electronics. A paper on the work is published in the journal NANO.
Due to its high security and capacity, titanium niobium oxide (TNO) has gained much attention as anode material for lithium-ion batteries. However, 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, combined utilized crystal structure modification, particle size reduction, porous structure, and conductive-phase compositing. The electrochemical performance, especially high-rate performance, of the material was significantly enhanced.
Ti2Nb10O29-x/HRGO hybrid was successfully fabricated by introducing vacancies into Ti2Nb10O29 (TNO) and hybridizing TNO with holey reduced graphene oxide (HRGO).
Morphology and rate capability of TNOx/HRGO. TNOx microspheres are wrapped by gossamer-like HRGO. Capacity is as high as 225 mAh/g and 173 mAh/g at 20 C and 40 C, respectively. Luo et al.
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.
This research was supported in part by grants from the National Natural Science Foundation of China (No. 51873240 and 51103141) and Sichuan Science and Technology Program (2019YJ0658).
Nan Luo, Guoliang Chen, Yunfan Shang, Suyang Lu, Jun Mei, Changyu Tang, Zhoukun He, Wenwen Zeng and Haoran Zhan (2020) “Porous Ti2Nb10O29−𝑥 Microspheres Wrapped by Holey-Reduced Graphene Oxide as Superior Anode Material for High-rate Performance Lithium-ion Storage” NANO doi: 10.1142/S1793292020500952