Coupling between oxygen redox and cation migration explains unusual electrochemistry in lithium-rich layered oxides

Abstract Lithium-rich layered transition metal oxide positive electrodes offer access to anion redox at high potentials, thereby promising high energy densities for lithium-ion batteries. However, anion redox is also associated with several unfavorable electrochemical properties, such as open-circuit voltage hysteresis. Here we reveal that in Li 1.17– x Ni 0.21 Co 0.08 Mn 0.54 O 2 , these properties arise from a strong coupling between anion redox and cation migration. We combine various X-ray spectroscopic, microscopic, and structural probes to show that partially reversible transition metal migration decreases the potential of the bulk oxygen redox couple by > 1 V, leading to a reordering in the anionic…

• UD
  U.S. Department of Energy

  Awards: -AC02-05CH11231, 76SF00515, 05CH11231, AC02-05CH11231, DE-AC02, DE-AC02-05CH11231, AC02-76SF00515, DE-AC02-
• SA
  Samsung Advanced Institute of Technology
• SN
  Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
• CS
  China Scholarship Council

  Award: DE-AC02-05CH11231
• HE
  Higher Education Discipline Innovation Project

  Award: B13029
• S
  Samsung
• OO
  Office of Science

  Awards: AC02-76SF00515, DE-AC02-76SF00515, AC02-05CH11231, -AC02-05CH11231, DE-AC02, 76SF00515
• DO
  Division of Materials Research
• BE
  Basic Energy Sciences

  Awards: DE-AC02, AC02-05CH11231, DE-AC02-76SF00515, DE-AC02-05CH11231, 76SF00515, AC02-76SF00515, -AC02-05CH11231
• SN
  SLAC National Accelerator Laboratory

  Awards: AC02-76SF00515, DE-AC02-76SF00515, DE-AC02-05CH11231