Improving cyclic stability of lithium nickel manganese oxide cathode at elevated temperature by using dimethyl phenylphosphonite as electrolyte additive

A novel electrolyte additive, dimethyl phenylphosphonite (DMPP), is reported in this paper to be able to improve significantly the cyclic stability of LiNi sub(0.5)Mn sub(1.5)O sub(4) cathode of high voltage lithium ion battery at elevated temperature. When experiencing charge/discharge cycling at 5...

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Bibliographic Details
Published in:Journal of power sources 2015, Vol.273, p.816-822
Main Authors: Mai, Shaowei, Xu, Mengqing, Liao, Xiaolin, Xing, Lidan, Li, Weishan
Format: Article
Language:English
Subjects:
Additives
Applied sciences
Bulk molding compounds
Cathodes
Dimethyl
Discharge
Electrical engineering. Electrical power engineering
Electrolytes
Exact sciences and technology
High temperature
Materials
Oxidation
Protective coatings
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Summary:A novel electrolyte additive, dimethyl phenylphosphonite (DMPP), is reported in this paper to be able to improve significantly the cyclic stability of LiNi sub(0.5)Mn sub(1.5)O sub(4) cathode of high voltage lithium ion battery at elevated temperature. When experiencing charge/discharge cycling at 50 [degrees]C with 1C (1C = 146.7 mAh g super(-1)) rate in a standard (STD) electrolyte (1.0 M LiPF sub(6) in ethylene carbonate (EC)/dimethyl carbonate (DMC), EC/DMC = 1/2 in volume), LiNi sub(0.5)Mn sub(1.5)O sub(4) suffers serious discharge capacity decaying, with a capacity retention of 42% after 100 cycles. With adding 0.5% DMPP into the STD electrolyte, the capacity retention is increased to 91%. This improvement can be ascribed to the preferential oxidation of DMPP to the STD electrolyte and the subsequent formation of a protective film on LiNi sub(0.5)Mn sub(1.5)O sub(4), which suppresses the electrolyte decomposition and protects LiNi sub(0.5)Mn sub(1.5)O sub(4) from destruction. Theoretical calculations together with voltammetric analyses demonstrate the preferential oxidation of DMPP and the consequent suppression of electrolyte decomposition, while the observations from scanning electron microscopy, X-ray photoelectronic spectroscopy and Fourier transform infrared spectroscopy confirm the protection that DMPP provides for LiNi sub(0.5)Mn sub(1.5)O sub(4).
ISSN:0378-7753
1873-2755
DOI:10.1016/j.jpowsour.2014.09.171