摘要
LiNi 0.6 Co 0.4-x Mn x O 2 (0.15 ≦ x ≦ 0.25) cathode materials for lithium-ion batteries are synthesized by calcining a mixture of Ni 0.6 Co 0.4-x Mn x (OH) 2 and Li 2 CO 3 at 890-950 °C for 15 h in a flowing oxygen atmosphere. The Ni 0.6 Co 0.4-x Mn x (OH) 2 precursor is obtained by a chemical co-precipitation method at pH = 11. Thermal analysis of the precursor for LiNi 0.6 Co 0.4-x Mn x O 2 (0.15 ≦ x ≦ 0.25) shows that the weight loss is about 30% until the temperature reaches 750 °C. The X-ray diffraction patterns indicate the pure, layered, hexagonal structure of LiNi 0.6 Co 0.4-x Mn x O 2 . Scanning electron micrographs reveal that the morphology of the samples is characterized by larger agglomerates (5-15 μm) of rather small layered particles (around 100 nm). The particle size tends to decrease with increasing Mn content. The electrochemical behaviour of LiNi 0.6 Co 0.4-x Mn x O 2 powder is examined by using test cells cycled within the voltage range 3-4.3 V at the 0.1 C rate for the first cycle and then at the 0.2 C rate. LiNi 0.6 Co 0.4-x Mn x O 2 (0.15 ≦ x ≦ 0.25) cathode materials exhibit good initial discharge capacity (165-180 mAh g -1 ) and a capacity retention of above 95% after 20 cycles. It is demonstrated that LiNi x Co y Mn 1-x-y O 2 electrodes are promising candidates for application as cathodes in lithium-ion batteries. © 2004 Elsevier B.V. All rights reserved.