Capacity fading of LiCr0.1Mn1.9O4/MPCF cells at elevated temperature

Abstract

Capacity fading of LiCr 0.1 Mn 1.9 O 4 /MPCF (mesophase pitch-based carbon fiber) cells was investigated at elevated temperature (55°C). The cells showed very fast capacity fading, keeping only 60% of capacity retention at the 100th cycle at 55°C. The cycled electrodes and the electrolyte were analyzed using electrochemical test, inductively coupled plasma, and X-ray diffraction. Results of the analyses indicated that LiCr 0.1 Mn 1.9 O 4 exhibited good effects on restraint of Mn dissolution and stabilization of structure at 55°C. The cycled LiCr 0.1 Mn 1.9 O 4 electrode and the cycled MPCF electrode presented good electrochemical performance again with fresh electrolyte. Therefore, it was proposed that the cycling fading of LiCr 0.1 Mn 1.9 O 4 / MPCF cells was mainly caused by decomposition of electrolyte upon LiCr 0.1 Mn 1.9 O 4 electrode during cycling. It was found that the decomposition of electrolyte led to the formation of a surface layer comprised of Li 2 CO 3 , Li x PF y , CH 3 OCO 2 Li or (CH 2 OCO 2 Li) 2 , polymeric ether etc. The formation of this film consumed active lithium ions, leading to fast capacity fading of LiCr 0.1 Mn 1.9 O 4 /MPCF cell at elevated temperature.

Investigation on the dissolution of Mn ions from LiMn2O4 cathode in the application of lithium ion batteries: First principle molecular orbital method

“…Doping is known to be an effective route. It is reported that substitution of Mn ions with other metals such as Li, Mg, Al, Cr, Co, Ni, Zn, Ga slows dissolution of Mn from the cathode into the electrolyte 15–27. Many researchers have reported that the introduction of cations with a low oxidation number increases the oxidation state of Mn ions.…”