ELECTROCHEMICAL PERFORMANCES OF COMPOSITE CATHODE MATERIALS Li_1.2Ni_0.17Co_0.10Mn_0.53O₂ and Li_1.2Ni_0.2Mn_0.6O₂

Highlights: • The composite materials Li1.2Ni0.17CРѕ 0.10Mn0.53O2 and Li1.2Mn0.6Ni0.2O2 comprise a mixture of primary solid solutions. • The discharge specific characteristics of the materials correspond to 230–250 mAh g−1 after 30 charge–discharge cycles. • The Li+ diffusion coefficients in the materials are mainly in the range of 10−14–10−18 cm2 s−1 at potentials of 3–4.7 V. - Abstract: The structural, morphological and electrochemical characteristics of the composite cathode materials Li_1.2Ni_0.17CРѕ _0.10Mn_0.53O₂ and Li_1.2Mn_0.6Ni_0.2O₂ have been investigated. Solution combustion synthesis has been used as the synthesis method. After heat treatment the average size of particle aggregates in both cathode materials was 5.9–6.5 μm. X-ray diffraction analysis shows that Li_1.2Ni_0.17CРѕ _0.10Mn_0.53O₂ and Li_1.2Mn_0.6Ni_0.2O₂ consist of a mixture of primary substitutional solid solutions based on phases with an α-NaFeO₂ and Li₂MnO₃ or an α-NaFeO₂, Li₂MnO₃ and LiMn₂O₄ structure. The discharge specific characteristics of these materials are characterized by values of 230–250 mAh g⁻¹. By using electrochemical impedance it was determined that the charge transfer resistance in the investigated materials is by an order of magnitude higher than that in the monophase layered materials of an α-NaFeO₂ type. The following kinetic parameters were determined: the diffusion coefficient Li⁺, the energy barrier at Li⁺ migration through the solid electrolyte interphase, and the activation energy of the intercalation/deintercalation reaction.