In Situ-Constructed Multifunctional Interface for High-Voltage 4.6 V LiCoO2

Chao Sun; Bing Zhao; Ru-de Cui; Jing Mao; Ke-Hua Dai; He-Zhang Chen; Xia-Hui Zhang; Jun-Chao Zheng

doi:10.1021/acsami.2c22642

In Situ-Constructed Multifunctional Interface for High-Voltage 4.6 V LiCoO₂

ACS Appl Mater Interfaces. 2023 May 10;15(18):21982-21993. doi: 10.1021/acsami.2c22642. Epub 2023 Apr 26.

Authors

Chao Sun^{1

2}, Bing Zhao³, Ru-de Cui¹, Jing Mao⁴, Ke-Hua Dai⁵, He-Zhang Chen⁶, Xia-Hui Zhang^{1

2

7}, Jun-Chao Zheng^{1

2}

Affiliations

¹ School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China.
² Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Central South University, Changsha 410083, China.
³ Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China.
⁴ School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China.
⁵ College of Chemistry, Tianjin Normal University, Tianjin 300387, China.
⁶ School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201, China.
⁷ School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164, United States.

PMID: 37098946
DOI: 10.1021/acsami.2c22642

Abstract

Due to high volumetric energy density, the major market share of cathode materials for lithium-ion batteries is still dominated by LiCoO₂ (LCO) at a 3C field. However, a number of challenges will be triggered if the charge voltage is increased from 4.2/4.3 to 4.6 V to further increase energy density, such as a violent interface reaction, Co dissolution, and release of lattice oxygen. Here, LCO is coated with the fast ionic conductor Li_1.8Sc_0.8Ti_1.2(PO₄)₃ (LSTP) to form LCO@LSTP, while a stable interface of LCO is in situ constructed by the decomposition of LSTP at the LSTP/LCO interface. As decomposition products of LSTP, Ti and Sc elements can be doped into LCO and thus reconstruct the interface from a layered structure to a spinel structure, which improves the stability of the interface. Moreover, Li₃PO₄ from the decomposition of LSTP and remaining LSTP coating as a fast ionic conductor can improve Li⁺ transport when compared with bare LCO, and thus boost the specific capacity to 185.3 mAh g^-1 at 1C. Benefited from the stable interface and fast ion conducting coating, the LCO@LSTP (1 wt %) cathode delivers a high capacity of 202.3 mAh g^-1 at the first cycle (0.5C, 3.0-4.6 V), and shows a higher capacity retention of 89.0% than LCO (50.9%) after 100 cycles. Furthermore, the change of the Fermi level obtained by using a kelvin probe force microscope (KPFM) and the oxygen band structure calculated by using density functional theory further illustrate that LSTP supports the performance of LCO. We anticipate that this study can improve the conversion efficiency of energy-storage devices.

Keywords: band-structure regulation; fast ionic conductor; interface reconstruction; lithium cobalt oxide cathode; lithium-ion batteries.