title: In Situ Multitechnical Investigation into Capacity Fading of High-Voltage LiNi0.5Co0.2Mn0.3O2.
abstract: LiNi0.5Co0.2Mn0.3O2positive electrode materials of lithium ion battery can release a discharge capacity larger than 200 mAh/g at high potential (>4.30 V). However, its inevitable capacity fading, which is greatly related to the structural evolution, reduces the cycling performance. The origin of this capacity fading is investigated by coupled in situ XRD-PITT-EIS. A new phase of NiMn2O4is discovered on the surface of the LiNi0.5Co0.2Mn0.3O2upon charging to high voltage, which blocks Li+diffusion pathways. Theoretical calculations predict the formation of cubic NiMn2O4. Moreover, corrosion, cracks, and microstress appear to increase the difficulty of Li+transportation, which are attributed to the protection degradation of the interfacial film on the positive electrode material at high voltage. After 50 electrochemical cycles, the increase in degree of crystal defects by low-angle grain boundary, evidenced through HR-TEM, leads to poor Li+kinetics, which in turn causes capacity loss. The in situ XRD-PITT-EIS technique can bring multiperspective insights into fading mechanism of the high-voltage positive electrode materials and provide a solution to control or suppress the problem on the basis of structural, kinetic, and electrochemical interfacial understandings.
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Chong-Heng
authors.initials: CH
authors.lastname: Shen
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Hong-Jiang
authors.initials: HJ
authors.lastname: Chen
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Chen-Guang
authors.initials: CG
authors.lastname: Shi
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Hui-Yi
authors.initials: HY
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Ling
authors.identifier: http://orcid.org/0000-0003-1092-5974
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Jun-Tao
authors.initials: JT
authors.lastname: Li
authors.affiliation: Department of Chemistry, College of Chemistry and Chemical Engineering and ‡College of Energy, Xiamen University , Xiamen, Fujian 361005, China.
authors.forename: Shi-Gang
authors.initials: SG
authors.lastname: Sun
keywords: LiNi0.5Co0.2Mn0.3O2; NiMn2O4; capacity fade; high voltage; in situ XRD-PITT-EIS