Enhanced electrochemical properties of potassium-doped lithium-rich oxide@carbon as cathode material for lithium-ion batteries

Yaxin Cheng; Zhen Wu; Xin Dai; Jixiang Hu; Zige Tai; Junjie Sun; Yan Liu; Qiang Tan; Yongning Liu

doi:10.1016/j.jcis.2021.07.141

Enhanced electrochemical properties of potassium-doped lithium-rich oxide@carbon as cathode material for lithium-ion batteries

J Colloid Interface Sci. 2022 Jan:605:718-726. doi: 10.1016/j.jcis.2021.07.141. Epub 2021 Jul 31.

Authors

Yaxin Cheng¹, Zhen Wu¹, Xin Dai¹, Jixiang Hu¹, Zige Tai², Junjie Sun¹, Yan Liu¹, Qiang Tan¹, Yongning Liu³

Affiliations

¹ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, PR China.
² Center for Nano Energy Materials, State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China.
³ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, PR China. Electronic address: ynliu@xjtu.edu.cn.

PMID: 34365308
DOI: 10.1016/j.jcis.2021.07.141

Abstract

Lithium-rich layered oxides are believed to be the most competitive cathode materials for next-generation lithium-ion batteries (LIBs) due to their high specific capacity, but the poor cycle stability and voltage attenuation severely limit their commercial applications. In this paper, a simple method combining surface treatment via pyrolysis of polyvinyl alcohol (PVA) and potassium ions (K⁺) doping, is designed to improve the above defects of the cobalt-free Lithium-rich material Li_1.2Mn_0.6Ni_0.2O₂ (LMR). The insoluble surface byproduct Li₂CO₃ and amorphous carbon nanolayer derived from the pyrolysis process of PVA alleviate the corrosion of acidic species with a favorable conductivity, while a large radius of K⁺ can enlarge the space of the lithium (Li) layer to facilitate the diffusion of Li⁺, suppress voltage polarization, and synchronously restrain the transformation from a layered structure to a spinel-like structure. After modification, the LMR material exhibits a great initial discharge capacity of 266.0 mAh g^-1 at 0.1C, a remarkable rate capability of 159.1 mAh g^-1 at 5C and an extremely high capacity retention of 98.5% over 200 cycles at 0.5C with a small voltage drop.

Keywords: Carbon nanolayer; Cycle and rate performance; Lattice spacing; Li(1.2)Mn(0.6)Ni(0.2)O(2); Li(2)CO(3).