LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-preci...LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.展开更多
LiNiO2 and LiNi0.5Co0.5O2 cathodes for lithium-ion batteries were synthesized with co-precipitation method and their electrochemical property was characterized by Galvanostatic cycling. Meanwhile, plane-wave pseudopot...LiNiO2 and LiNi0.5Co0.5O2 cathodes for lithium-ion batteries were synthesized with co-precipitation method and their electrochemical property was characterized by Galvanostatic cycling. Meanwhile, plane-wave pseudopotential method base on density functional theory was used to calculate average cell voltage and the electronic structure of LiNiO2 and LiNi0.5Co0.5O2. The experimental and computational results showed that the average voltage of the cell decreased as Li-ion intercalated to the host cathode (discharge); The potential of LixNi0.5Co0.5O2 was higher than that of LixNiO2 (when 0.25≤x≤0.5). The calculations also indicated that the distortion of the NiO6 octahedron in LixNiO2 was decreased by Co-doped. During the Li-ion intercalates to the host cathode, the micro-structures of NiO6 and CoO6 in the LixNi0.5Co0.5O2 were mutually stabilized, the Jahn-Teller effect was weakened and the electrochemical properties of the materials were enhanced.展开更多
文摘LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.
文摘LiNiO2 and LiNi0.5Co0.5O2 cathodes for lithium-ion batteries were synthesized with co-precipitation method and their electrochemical property was characterized by Galvanostatic cycling. Meanwhile, plane-wave pseudopotential method base on density functional theory was used to calculate average cell voltage and the electronic structure of LiNiO2 and LiNi0.5Co0.5O2. The experimental and computational results showed that the average voltage of the cell decreased as Li-ion intercalated to the host cathode (discharge); The potential of LixNi0.5Co0.5O2 was higher than that of LixNiO2 (when 0.25≤x≤0.5). The calculations also indicated that the distortion of the NiO6 octahedron in LixNiO2 was decreased by Co-doped. During the Li-ion intercalates to the host cathode, the micro-structures of NiO6 and CoO6 in the LixNi0.5Co0.5O2 were mutually stabilized, the Jahn-Teller effect was weakened and the electrochemical properties of the materials were enhanced.
