Limitation af Cathode Electrolyte Reaction in Lithium Ion Batteries

One of the main drawbacks of the lithiated oxides such as LiNi0.8Co0.2O2 is the strong interaction between the electrode and the electrolyte which can lead to exothermic reactions upon cycling and thus presents a major risk of thermal hazard in a lithium ion battery. To prevent this exothermic reaction, we have tried to protect the surface of the LiNi0.8Co0.2O2 particles by a thin layer of Li3xLa2/3-x[]1/3-2xTiO3 which is a good Li-ion conductor. The aim was to enable the lithium to intercalate into the cathode material through the coating layer and to prevent the surface of the cathode to be directly in contact with the electrolyte. The treatment has been performed by sol-gel method. Precursors of lithium, lanthanum and titanium have been dissolved in propylene glycol, 2-propanol or ethanol in appropriate amounts. The cathode powder has been dispersed in the solution and stirred. After evaporating the solvent, the powder was heated at 800°C for 24 h.