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摘要互联网时代发展日新月异，手机，电脑，ipad等一大批电子产品也不断改变着我们的日常生活。锂离子电池作为各类电子产品的储能部分，越来越多的受到人们的关注。LiCoVO4为反尖晶石结构，理论容量148mAh/g，具有能量密度高，放电稳定等优点。本文使用改进的固相法合成LiCoVO4正极材料。实验中我们发现400℃是最好的煅烧温度，在该温度下煅烧其首次放电比容量为64mAh/g，相比于300℃（56mAh/g）和500℃（54mAh/g）的比容量都要高。在400℃合成不同(PO4)3-取代(VO4)3-的LiCo(VO4)1-X(PO4)X（X=0.05，0.1，0.2）正极材料。研究发现当X=0.1时LiCo(VO4)1-X(PO4)X的电化学性能最好，首次充电比容量为69mAh/g。考虑到LiCoVO4较低的导电性，使用不同含量的石墨烯来提高LiCoVO4的电导率，经试验探究发现随着石墨烯含量的增加，正极材料的电化学性能越好，当石墨烯含量超过1.5%时正极材料的电化学性能保持不变，说明只要加入1.5%的石墨烯就可以得到较好的电化学性能。62222
毕业论文关键词：锂离子电池；LiCoVO4；(PO4)3-取代；石墨烯
Effect of different graphene contents on the electrochemical properties of LiCo (VO4)1-X(PO4) X
Abstract With the rapid development of the Internet era, mobile phone, computer, iPad and other electronic products have been changing our daily life. lithium ion batteries as storage part, get more and more people's attention.LiCoVO4 is anti-spinel structure, the theoretical capacity is 148mAh/g, which has the advantages of high energy density, stable discharge and so on. In this paper, the LiCoVO4 cathode material was synthesized by the improved solid state method. In the experiment, we found that 400℃ is the best calcination temperature, the first discharge capacity of calcined at 400℃ is 64mAh/g, which is higher compared to 300℃ (56mAh/g) and 500 C (54mAh/g). Respectively, LiCo(VO4)1-X(PO4)X(X=0.05，0.1，0.2) cathode materials were prepared at 400℃. Research found that LiCo(VO4)1-X(PO4)X has the best electrochemical performance when X=0.1, the first discharge ratio is 69mAh/g. Taking into account the LiCoVO4 lower conductivity, using different content of graphite to improve LiCoVO4 conductivity, the experiment research found that electrochemical performance of cathode material become better with the increasing of the content of graphene. When the content of graphene is 1.5% the cathode material has best electrochemical performance.
KeyWords: lithium ion battery; LiCoVO4; (PO4)3- substitution; graphene
1 绪论 1
1.1 电池发展背景 1
1.2 锂离子电池工作原理 2
1.3 锂离子正极材料 3
1.3.1 LiCoO2-层状结构代表 3
1.3.2 LiMn2O4-尖晶石结构代表 4
1.3.3 LiFePO4-橄榄石型结构代表 4
1.4 LICOVO4正极材料 4
1.5 课题研究内容 6
1.5.1 研究方向 6
1.5.2 研究方案 6
1.5.3 原料合成方法 7
1.5.4 实验测试仪器基本参数 7
1.5.5 研究要求 7
2 实验及表征 8
2.1 实验原料 8
2.2 实验设备 8
2.3 原料制备过程 9
2.4 正极材料制备及电池组装过程