Insights into Layered Oxide Cathodes for Rechargeable Batteries

Abstract

Layered intercalation compounds are the dominant cathode materials for rechargeable Li-ion batteries. In this article we summarize in a pedagogical way our work in understanding how the structure’s topology, electronic structure, and chemistry interact to determine its electrochemical performance. We discuss how alkali–alkali interactions within the Li layer influence the voltage profile, the role of the transition metal electronic structure in dictating O3-structural stability, and the mechanism for alkali diffusion. We then briefly delve into emerging, next-generation Li-ion cathodes that move beyond layered intercalation hosts by discussing disordered rocksalt Li-excess structures, a class of materials which may be essential in circumventing impending resource limitations in our era of clean energy technology.

In Honor of John Bannister Goodenough, an Outstanding Visionary

“…(1) The article by Julia H. Yang, Haegyeom Kim and Gerbrand Ceder [7] perfectly illustrates the philosophy of Goodenough concerning his pursuit to understand the structureproperty relationship, rationalize experimental observations and improve the characteristics of a studied material or device. On the basis of DFT calculations, the authors evidence how the topology of layered structures impacts the electrochemical performances.…”

Alleviating Anisotropic Volume Variation at Comparable Li Utilization during Cycling of Ni-Rich, Co-Free Layered Oxide Cathode Materials

“…However, in practice modern LiCoO 2 cells are typically operated up to a lower cutoff voltage to avoid fast capacity fading caused by excessive mechanical degradation (≈165 mAh g –1 at 4.35 V) . As discussed above, the observed electrochemical behavior and associated phase transitions in ternary layered oxide phases can be related to the changing electronic configuration of the active transition-metal ions during delithiation. − Hence, the introduction of substituent atoms to produce more complex quaternary (e.g., Li–Ni–Mn–O) or quintenary (e.g., Li–Ni–Mn–Co–O) phases should also be expected to influence the electronic configuration of adjacent metal ions and thereby influence the potential at which a given cation redox couple is active. − The preparation of solid solutions of these ternary layered oxides allows for the redox activity and advantageous physical properties of the basic ternary phases to be harnessed in a homogeneous phase, as shown in Figure . The composition of the resulting solid solutions is also consequential for the potential at which each TM redox couple is active.…”

Activated Internetwork Pathways in Partially‐Disordered Spinel Cathode Materials with Ultrahigh Rate Performance

“…[1] Hence, all layered state-of-the-art cathodes rely on Co and Ni. [2,3] Today, it is understood that advanced cathode compounds do not actually need to be well-ordered to deliver high capacity and energy density. [4,5] The cation-disordered lithium-excess (DRX) class of compounds is a promising route to achieve lower cost per kilowatt-hour as they remove any dependency on Co or Ni, and can instead be based on earth-abundant, manganese.…”