Papers by Keyword: Cation Mixing

Abstract: A LiNi_0.4Co_0.2Mn_0.4O₂ material was prepared via the co-precipitation in solution and ensuing solid reaction of the prepared precursors with LiOH.H₂O, investigating the influence of solid reaction temperature on the cation mixing and electrochemical performance of the materials as a cathode. The results show that Li⁺/Ni²⁺ cation mixing decreases with the increase of calcination temperature in the range of 700-900°C, and the lower degree of cation mixing can improve 2D layered structure and make the material more stable. The discharge capacity and the capacity retention rate of the material is strongly impacted by the reaction temperature.The powders calcined at 900°C show the best electrochemical performance and the initial discharge capacity is 163.1mA·h/g, after 40 cycles, the capacity retention rate is 93.9%.

Abstract: Ni_0.8Co_0.1Mn_0.1(OH)₂ precursors prepared by co-precipitation method were served to synthesize LiNi_0.8Co_0.1Mn_0.10₂ cathode materials by sintering with LiOH·H₂O at high temperature. It is shown from XRD analysis and electrochemical measurements that these precursors synthesized at different aging time are all composed of two phases, α-Ni (OH)₂ and β-Ni (OH)₂.With aging process lasting longer,relatively content of α-Ni (OH)₂ in precursors increase , peak intensity ratios of I₍₀₀₃₎/I₍₁₀₄₎ in LiNi_0.8Co_0.1Mn_0.10₂ get larger, the more complete of layer structure, the lower of Li⁺/Ni²⁺cation mixing. Results indicate that the existence and content increase of α-Ni (OH)₂ phase with aging process lasting can inhibit the cation mixing efficaciously. LiNi_0.8Co_0.1Mn_0.10₂ obtained from precursor aged 12h has a good cyclic performance, capacity retention rate reaches 92.8% after 30 cycles.

Abstract: To investigate the effect of oxygen pressure on the synthesis of LiNiO2 cathode material for Li secondary battery, powder was prepared by emulsion method and calcined at 750°C for 24 h under various oxygen gas pressures. LiNiO2 single phase could be synthesized under oxygen pressure of 101.3~103.3 kPa but not under air atmosphere. Cation mixing in Li site of LiNiO2 lowered as oxygen pressure increased and was saturated around 103.3 kPa. The lowest cation mixing, 7.0% of Ni3+ in the Li site was obtained at 750°C for 24 h under 103.3 kPa of oxygen pressure.