Sn-Cl共掺杂的锂离子正极材料Li2MnO3的结构及电化学性能研究  

Structures and Electrochemical Properties of Sn-Cl Co-Doped Li2MnO3 as Positive Materials for Lithium Ion Batteries

作　　者：王非 翟欢欢 王杜丹 李玉鹏 陈康华[1,2] WANG Fei;ZHAI Huan-huan;WANG Du-dan;LI Yu-peng;CHEN Kang-hua(Powder Metallurgy Research Institute,Central South University,Changsha 410083,China;State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China)

机构地区：[1]中南大学粉末冶金研究院,湖南长沙410083 [2]中南大学粉末冶金国家重点实验室,湖南长沙410083

出　　处：《电化学》2020年第1期148-155,共8页Journal of Electrochemistry

基　　金：国家重点研发计划(No.2016YFB0300801);国家自然科学基金重大科研仪器设备研制专项(No.51327902)资助。

摘　　要：以乙酸盐为原料,柠檬酸为络合剂,通过溶胶-凝胶的方法制备富锂阴极材料Li2MnO3,选用草酸亚锡(SnC2O4)为锡源,用Sn4+代替Mn4+,获得不同掺杂量的材料.适当含量的Sn4+掺杂可以提高材料的放电比容量,在低电流下获得256.3 mAh·g-1的高放电比容量,但由于Sn4+离子半径过大,不能起到稳定结构的作用,材料的倍率性能较差.在此基础上,选用氯化亚锡(SnCl2)进行掺杂改性,在材料中同时引入Sn4+和Cl-掺杂,获得了层状结构更完整的粉末样品.通过共掺杂改性的阴极材料可以在20 mA·g-1的电流密度,经过80圈的循环仍然保持153mAh·g-1的放电比容量,且此时还未出现衰减现象,库仑效率保持在96%以上;在400 mA·g-1的电流密度下提供的比容量可高达116 mAh·g-1,是未掺杂样品的2倍左右.Positive material Li2MnO3 shows the highest ratio of lithium to manganese among lithium-rich materials and exhibites the theoretical capacity up to 458 mAh·g-1, making it one of the most promising cathode materials. However, this material has the intrinsic low electrical conductivity and poor cycle stability. In this paper, Li2MnO3, the lithium-rich positive material, was prepared by sol-gel method using acetate as raw material and citric acid as a complexing agent. By using SnC2O4 as a tin source,Sn4+instead of Mn4+ was introduced to obtain the materials with different doping amounts. The resultant solution was evaporated at 80 °C under vigorous stirring to get a viscous gel. Next, the resulting gel was dried at 120 ° C for 12 h. Finally, the gathered precursor was calcined at 600 °C for 6 h under an air atmosphere to obtain the target material. It was found that the proper content of Sn4+doping could increase the specific discharge capacity of the material, obtaining as high as 256.3 mAh·g-1 at low current, but had a detrimental influence on the rate performance. On this basis, SnCl2 was used for doping modification, and the Sn4+ and Clco-doping into Li2MnO3 revealed a better developed layered structure with high conductivity. The intensity of super lattice peak formed between 2θ = 20° and 30° was increased by Cl-doping, indicating the ordered Li/Mn in the TM layer. Especially, this Sn-Cl co-doped Li2MnO3 sample delivered the relatively high specific discharge capacity of approximate 160 mAh·g-1 after 80 cycles at 20 mA·g-1. At the high current density of 400 mA·g-1, this material provided the specific discharge capacity of 116 mAh·g-1, which is about twice that of the undoped sample.

关 键 词：锂离子电池 正极材料 LI2MNO3 草酸亚锡 氯化亚锡 Sn-Cl共掺杂 

分 类 号：TM911[电气工程—电力电子与电力传动] O646[理学—物理化学]