The Reaction of Charged Cathodes with Nonaqueous Solvents and Electrolytes: II. LiMn[sub 2]O[sub 4] charged to 4.2 V

The thermal decomposition of charged to 4.2 V was studied using a combination of accelerating rate calorimetry and X-ray diffraction. The electrolyte and solvent were removed from the surface of the electrode using a rinsing procedure. Then electrode samples were either heated dry with solvent added or with electrolyte added. The dry electrode was determined to convert from the structure to the structure upon exposure to elevated temperatures (below 300°C). In the presence of solvent, there is solvent oxidation and reduction to MnO. The reaction of with was also studied. The reactivity increases as the salt concentration increases. These experiments point the way to safer lithium-ion cells using since electrodes in electrolytes with lower concentrations of than, for example, 1 M, demonstrate improved thermal behavior.