Chemical interaction in the cathode half-element of lithium ion batteries

Chemical interactions in the cathode half-element of lithium ion batteries with LiCoO₂ as cathode and 1.15 M ILiPF₆, in mixture of al-kylcarbonates as electrolyte had been studied by using a number of calculation and experimental methods. It was found that the layer of chemical interactions products on the surface of LiCoO₂ grains comprised LiF and LiPO₃ and, also, CoF₂, which passed to the electrolyte solution with time. Moreover, the LiCoO₂ surface was covered with a layer of alkyl carbonate polymerization products. It was demonstrated that the performance of the batteries was impaired due to the mutual thermodynamic instability of LiCoO₂ and LiPF₆. The electron short-circuiting which was due to appearance of Соⁿ⁺ ions in the electrolyte contributed most to the batteries degradation process.