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层状正极材料 LiCo1/3Mn1/3Ni1/3O2 的合成和电化学性能研究
李志刚
学位类型硕士
导师康雪雅
2007-06
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业微电子学与固体电子学
关键词层状正极材料 Lico1/3mn1/3ni1/3o2 掺杂改性
摘要

随着人们对便携式能源需求的增加,锂离子二次电池以其高比能量密度得到日
益广泛的应用。商业化的锂离子二次电池以LiCoO2 作为正极材料,但是LiCoO2 的放电比容量只有140mAh/g,仅仅达到其理论容量的50%,况且钴有毒、资源少且价格高, 科研工作者一直在寻求可能的替代物。层状复合正极材料
LiCo1/3Mn1/3Ni1/3O2 综合了LiCoO2、 LiNiO2 和 LiMnO2 的优点,具有优良的电化学性能和安全性,已经成为了人们研究的热点。本论文系统的研究了LiCo1/3Mn1/3Ni1/3O2 的合成方法、合成条件、电化学性能,制备出了性能较好的层状正极材料LiCo1/3Mn1/3Ni1/3O2;并对其进行掺杂改性,改善了其循环性能。本论文首次采用新方法Pechini 法合成纯相正极材料LiCo1/3Mn1/3Ni1/3O2,其α-NaFeO2 层状结构发育良好,颗粒分布范围为20-200nm,振实密度为0.81g/cm3。放电容量在150mAh/g 以上,比目前商业化的LiCoO2 的放电容量高。共沉淀法合成的材料层状结构发育良好,颗粒粒度分布范围为500-3000nm,振实密度为1.76 g/cm3。放电容量在160mAh/g 以上。通过掺杂量为0.03 的Al3+离子掺杂,其循环性能提高了近10 个百分点。解释了掺杂后电化学性能提高的原因。固相法合成的材料晶体结构中有一些NiO 杂相。颗粒粒度比较大。其放电容量一般在90 mAh/g 以上。5 次循环的容量保持率在95%以上。在本论文中,还简略探讨了Pechini 法和共沉淀法的合成机理。

其他摘要

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.

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/3505
专题材料物理与化学研究室
作者单位中国科学院新疆理化技术研究所
推荐引用方式
GB/T 7714
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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