LiCoO2梯度包覆LiNi0.96Co0.04O2电极材料的电化学性能

镍钴酸锂(LiNi0.8Co0.2O2)与目前商业用锂离子电池正极材料钴酸锂(LiCoO2)相比,具有成本低、实际比容量高和环境友好等优势。但LiNi0.8Co0.2O2的充放循环性能还有待提高,对其进行阳离子掺杂或表面修饰可以改善其电化学性能,这方面的研究已经成为热点。Fey等人1]用溶胶凝胶法制

Electrochemical Performance of LiCoO2 Gradient Coated LiNi0.96Co0.04O2 Cathode

LiCoO₂ gradient coated LiNi_0.96Co_0.04O₂ material and iso-structure LiNi_0.8Co_0.2O₂ 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 LiNi_0.8Co_0.2O₂ 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 100^th 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.