Lithium diffusion behavior and improved high rate capacity of LiNi sub(1/3)Co sub(1/3)Mn sub(1/3)O sub(2) as cathode material for lithium batteries

• Published in: Solid state ionics 2012-01, Vol.207, p.50-56
• Main Authors: Gao, Po, Yang, Gang, Liu, Haidong, Wang, Lu, Zhou, Haishan
• Format: Article
• Language: English
• Subjects: Cut-off; Diffusion rate; Discharge; Electric potential; Electrochemical impedance spectroscopy; Electrodes; Ethyl alcohol
• ISSN: 0167-2738
• DOI: 10.1016/j.ssi.2011.11.020

Homogeneous particles of LiNi sub(1/3)Co sub(1/3)Mn sub(1/3)O sub(2) are synthesized at 900 degree C for 24 h (LNCM-24H) based on the precursors formed in ethanol. Cyclic voltammetry (CVs) profiles of the sample LNCM-24H have been recorded under various scan rates. The calculated diffusion coefficients of Li super(+) in solid-state electrode well explain the kinetic process of the oxidation/reduction reactions. Based on the simulated data of electrochemical impedance spectroscopy (EIS), Li super(+) diffusion through the electrode surface is relatively faster than that in the lattice of cathode material which present relative smaller R sub(f) and R sub(Li) appear compared with W-R and W-T. The big capacitances CPE1P and CPE2P are attributable to positive charges that accumulate on the interfaces which involve the phase changes of Li super(+). The sample LNCM-24H worked at the cut-off voltage 4.4 V exhibits an improved discharge capacity of 197.9 mAh g super(-1) at 0.1 C, and can remain 95% capacity after 50 cycles. For the usage of energy storage device, the sample LNCM-24H presents very good in-situ electrochemical performance under various temperature and current rates. Under the cut-off voltage 4.4 V, the sample LNCM-24H presents a high discharge capacity of 243 mAh g super(-1) and very good cycleability after 50 cycles at 50 degree C. Under a continuous changing temperature (range from 0 to 50 degree C), higher and stable discharge capacity still remains.