Studies of LiMn2O4 Capacity Fading Mechanism at Elevated Temperature Using In Situ Synchrotron X-Ray Diffraction

Journal Article · Sun Jan 01 04:00:00 EST 2006 · J. Electrochem. Soc.

DOI:https://doi.org/10.1149/1.2172565· OSTI ID:914182

Chung, K; Lee, H; Yoon, W; McBreen, J; Yang, X

Using in situ X-ray diffraction, the capacity fading mechanism of LiMn{sub 2}O{sub 4} under various conditions has been studied. The capacity fading can be monitored by the structural changes during cycling. At the beginning of cycling, the structural changes closely follow the charge-discharge curve: the main structure starts in cubic I, transfers to cubic II, and ends as cubic III during charge, and reverses the course during discharge. These phase transitions track the charging and discharging curves with small hysteresis. However, with an increased amount of capacity fading during cycling, the structural changes deviate from the charge-discharge curve: Bragg peaks representing cubic I and II remain present at the end of charge, when the whole cathode should have been transferred to cubic III. Similarly, the residues of cubic II and III were observed at the end of discharge. The amount of residues increases with increasing capacity fading by cycling at 55 C, overcharging to 5.2 V, or after multiple cycling at normal condition. Adding a tris(pentafluorophenyl) borane (TPFPB) compound in electrolyte can reduce the residues and washing the cathode with solvent can partially restore the lost capacity in the subsequent cycling, showing the important role of electrolyte decomposition in capacity fading.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 914182
• Report Number(s): BNL--78750-2007-JA
• Journal Information: J. Electrochem. Soc., Journal Name: J. Electrochem. Soc. Vol. 153; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BORANES
BRAGG CURVE
CAPACITY
CATHODES
ELECTROLYTES
HYSTERESIS
RESIDUES
SOLVENTS
SYNCHROTRONS
WASHING
X-RAY DIFFRACTION
national synchrotron light source