【作者】 段冰洁；

【导师】 高虹；

【作者基本信息】 沈阳理工大学 ， 应用化学， 2008， 硕士

【摘要】 锂镍氧系电极材料是锂离子电池正极材料的研究热点之一,虽然人们已经成功制备出LiNi_0.8Co_0.2O₂材料,但因其仍存在循环性能差等问题仍未得到广泛的应用,必须对材料进行改性。显而易见球形LiNi_0.8Co_0.2O₂较一般非球形LiNi_0.8Co_0.2O₂易于进行表面修饰,所以本论文成功制备出球形LiNi_0.8Co_0.2O₂便为今后人们对其进行改性研究打下了良好的基础,提供了易于修饰的优良原材料。此外,球形LiNi_0.8Co_0.2O₂还具有较高的振实密度、体积比容量,因此其在小型化的电子仪器和设备乃至航天技术上的应用便具有了一般非球形LiNi_0.8Co_0.2O₂不可比拟的优势。本论文通过控制结晶法合成球形前驱体材料Ni_0.8Co_0.2（OH）₂,经工艺的层层筛选、不断优化,得出最佳工艺:反应物浓度分别为CNiSO₄=0.5mol/L、CCoSO₄=0.5mol/L、CNaOH=1mol/L、CNH₃·H₂O=1mol/L;反应体系pH=11.2;体系温度为55℃;氨镍比=0.8:1;反应时间为24h;搅拌速度为800r/min;陈化时间为3h。前驱体晶形成长致密,球形度好,振实密度为2.0271g/cm³,粒径分布均匀,为球形锂离子电池正极材料LiNi_0.8Co_0.2O₂的制备提供了良好的前驱体材料。本论文锂离子电池正极球形材料LiNi_0.8Co_0.2O₂的制备过程中采用浸渍液超声波振荡法混合原料,此方法原料混合均匀,分散性好;采用二次高温烧结法制备最终产品。最终得出最佳工艺为:氧气流量40mL/min,Li:（Ni+Co）= 1.10:1,第一次煅烧温度为650℃,恒温时间12h,第二次煅烧温度为720℃,恒温时间为5小时。产品颗粒通过SEM扫描电子显微镜观察表明其形貌为球形;通过激光粒度仪测试表明其粒度分布均匀;经XRD分析证明产品晶体结构完整,晶形良好;通过ICP测试表明Li:（Ni+Co）=1.01:1;通过密度测试测出其振实密度为2.7930 g/cm³;通过电化学工作站进行循环伏安测试表明产品具有较好的电化学可逆性;通过电池性能测试仪测试,产品首次充电质量容量为196.86mAh/g,首次放电质量容量为176.93mAh/g,相应体积容量分别可达549.83mAh/cm³,494.17 mAh/cm³,100次循环后,容量保持率为76.28%。更多还原

【Abstract】 Lithium-nickel-oxygen series cathode materials are promising candidates for lithium ion batteries. LiNi_0.8Co_0.2O₂ material had been successfully prepared by scientists, but it could not be widely applied because this series materials still possess various problems like the dissatisfied cycle performance, so improving performance study is necessary. Obviously, spherical material LiNi_0.8Co_0.2O₂ can be made a surface decoration much more easily than non-spherical lithium ion batteries anode material, the successful preparation of spherical material LiNi_0.8Co_0.2O₂ in this paper can lay a good foundation and provide a excellent original material for other people who want to improve materials performance. Besides, spherical material LiNi_0.8Co_0.2O₂ has high density and volume capability, so it has its own predominance than non-spherical Li-ion batteries anode material when it is used in small electronic equipment and even more used in spaceflight technology.This paper prepared spherical precursor material Ni_0.8Co_0.2（OH）₂ through controlled crystallization method, through many filtration and incessant optimization, finally found out best technics: the concentration of reactants were CNiSO₄=0.5mol/L, CCoSO₄=0.5mol/L, CNaOH=1mol/L, CNH₃·H₂O=1mol/L, pH=11.2, temperature was 55℃, NH₃:Ni₂⁺=0.8:1, reaction time was 24h, mix round speed was 800r/min, deposit time was 3h. The spherical precursor materials Ni_0.8Co_0.2（OH）₂ prepared by best technics had a compact crystal, good sphericity, the density was 2.0271g/cm3, granularity distributing is well and provide a better precursor for preparing spherical anode material LiNi_0.8Co_0.2O₂.In this paper original materials were mixed by steep ultrasonic oscillation, spherical anode materials LiNi_0.8Co_0.2O₂ were synthesised by sintering twice. The best synthesis technics was: oxide flux was 40mL/min, Li:（Ni+Co）= 1.10:1, sintered for 12h at 650℃at the first time, sintered for 5h at 720℃at the second time. Anode materials LiNi_0.8Co_0.2O₂ synthesized by the best technics were spherical had been proved by SEM, well granularity distributing were proved by laser partical sizer, cation arrangement were regular and crystal structure were integrated could be proved by X-ray diffraction analysis, Li:（Ni +Co）=1.01:1 were proved by ICP-MS, its density could reach 2.7930 g/cm³. In the voltage range of 2.8⁴.4V and at a specific current of 0.2 C the spherical anode material LiNi_0.8Co_0.2O₂ exhibited first charge quality capacity of 196.86mAh/g, first discharge quality capacity of 176.93mAh/g, corresponding volume capacity can reach 549.83mAh/cm³ and 494.17 mAh/cm³, and the capacity retention ratio is 76.28% after 100 cycling.更多还原