|层状正极材料 LiCo1/3Mn1/3Ni1/3O2 的合成和电化学性能研究|
|关键词||层状正极材料 Lico1/3mn1/3ni1/3o2 掺杂改性|
As the demand for portable and light-weight power source is increasing, lithium-ion batteries are in wide-spread use due to their higher energy density compared to traditional rechargeable systems. Commercial lithium-ion cells presently use LiCoO2 as the cathode. However, with a reversible capacity of 140mAh/g, only 50% of the theoretical capacity could be utilized. Recently, layered cathode material LiCo1/3Mn1/3Ni1/3O2, which integrates all the merits of LiCoO2, LiNiO2 and LiMnO2, has been extensively investigated due to its excellent electrochemical and safety characteristics. The synthesis method, synthesis conditions and electrochemical behavior were studied systemically in this dissertation. We have synthesized the layered LiCo1/3Mn1/3Ni1/3O2 cathode materials possessed superior performance. And the doping of layered LiCo1/3Mn1/3Ni1/3O2 cathode materials for improving the cycle performance was further studied. Phase-pure layered cathode material LiCo1/3Ni1/3Mn1/3O2 was synthesized by Pechini process firstly. Its α-NaFeO2 structure developed very well. The particle sizes were distributed from 20 to 200nm. Its tapped density is 0.81g/cm3. The discharge capacity of the cathode material which synthesized by Pechini method was bigger than 150mAh/g. It’s more than that of commercial lithium-ion cathode LiCoO2. The cathode material which synthesized by co-precipitation method also had a phase-pure α-NaFeO2 structure. Its particle sizes were distributed from 500 to 3000nm. The discharge capacity of the cathode material which synthesized by co-precipitation method was bigger than 160mAh/g. The Al3+ doping modification was studied. The doping amount 0.03 was the better. After the doping modification, the cycle performance had improved about 10%. The reason was explained in detail. The cathode material which synthesized by solid state method had a trace amount of impurity, NiO. Its particle sizes were big. The first discharge capacity of the cathode material which synthesized by solid state method was bigger than 90mAh/g. But its capacity retained higher than 95% after 5 cycles. The synthesis mechanism of Pechini process and co-precipitation were discussed in curtail.
|李志刚. 层状正极材料 LiCo1/3Mn1/3Ni1/3O2 的合成和电化学性能研究[D]. 北京. 中国科学院研究生院,2007.|
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