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

Authors

Fei WANG, 1. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China;2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
Huan-huan ZHAI, 2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
Du-dan WANG, 2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
Yu-peng LI, 1. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China;2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
Kang-hua CHEN, 1. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China;2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;Follow

Corresponding Author

Kang-hua CHEN(kanghuachen@csu.edu.cn)

Abstract

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 Cl^- co-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.

Graphical Abstract

Keywords

lithium ion battery, positive electrode material, Li2MnO3, SnC2O4, SnCl2, Sn-Cl co-doping

DOI Link

https://doi.org/10.13208/j.electrochem.190313

Publication Date

2020-02-28

Online Available Date

2019-06-29

Revised Date

2019-06-28

Received Date

2019-03-13

Recommended Citation

Fei WANG, Huan-huan ZHAI, Du-dan WANG, Yu-peng LI, Kang-hua CHEN. Structures and Electrochemical Properties of Sn-Cl Co-Doped Li₂MnO₃ as Positive Materials for Lithium Ion Batteries[J]. Journal of Electrochemistry, 2020 , 26(1): 148-155.
DOI: 10.13208/j.electrochem.190313
Available at: https://jelectrochem.xmu.edu.cn/journal/vol26/iss1/3