Hybrid LiV sub(3)O sub(8)/carbon encapsulated Li sub(1.2)Mn sub(0.54)Co sub(0.13)Ni sub(0.13)O sub(2) with improved electrochemical properties for lithium ion batteries

• Published in: RSC advances Vol. 6; no. 34; pp. 28729 - 28736
• Main Authors: Sun, Kailing, Peng, Can, Li, Zhaohui, Xiao, Qichang, Lei, Gangtie, Xiao, Qizhen, Ding, Yanhuai, Hu, Zhongliang
• Format: Journal Article
• Language: English
• Published: 01.03.2016
• Subjects: Carbon; Electrochemical analysis; Electrochemical impedance spectroscopy; Encapsulation; Lithium; Lithium-ion batteries; Nanoparticles; Rechargeable batteries
• ISSN: 2046-2069
• DOI: 10.1039/c6ra02688e

A low coulombic efficiency in the first cycle and poor rate capability limit the practical application of a lithium rich manganese-based solid solution (LMSS) in lithium ion batteries. To resolve these problems, a core-shell type of Li sub(1.2)Mn sub(0.54)Co sub(0.13)Ni sub(0.13)O sub(2)iV sub(3)O sub(8)/C (LMSSVC) composite material was prepared using a sol-gel process, in which NH sub(4)VO sub(3)-derived V sub(2)O sub(5) chemically leached lithium from the LMSS and formed the LiV sub(3)O sub(8) during high temperature annealing. The effect of the hybrid LiV sub(3)O sub(8)/C layer on the electrochemical properties of the LMSS is investigated using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge measurements. The as-prepared LiV sub(3)O sub(8) nanoparticles are embedded within the carbon matrix uniformly, which becomes an outer shell to encapsulate the LMSS nanoparticles. Because of the Li-host nature of LiV sub(3)O sub(8) and the electronic conductivity of carbon, the LMSSVC can deliver a capacity of 269 mA h g super(-1) at a 0.1C rate in the first cycle over the voltage range of 2.0-4.8 V together with a coulombic efficiency of 94%, and retain 94% of the initial capacity after 50 cycles. It can deliver capacities of 258, 245, 229, 207 and 176 mA h g super(-1) at the rates of 0.2C, 0.5C, 1C, 2C and 5C, respectively. The results indicate that surface coating of the hybrid LiV sub(3)O sub(8)/C layer can improve not only the initial coulombic efficiency but also the rate capability of the LMSS material.