Modulating the Surface Ligand Orientation for Stabilized Anionic Redox in Li‐Rich Oxide Cathodes

Abstract

Anionic redox chemistry is emerging as a key concept in the development of high‐energy lithium‐ion batteries, as it enables a nearly doubled charge storage capacity, aiding the development of high‐capacity batteries. However, the anionic reactivity is frequently irreversible from charge to discharge, leading to rapid decay of the capacity and voltage of batteries over long‐term cycling. Although the possibility of controlling the anionic redox reactions by tuning the geometric and electronic structures has recently been proposed, the implementation of this strategy is still a critical challenge. Herein, a strategy is proposed to improve the anionic redox reversibility of a model anionic redox active cathode material, Li1.2Ni0.13Co0.13Mn0.54O2, by tuning the surface ligand geometry via the growth of a lattice‐compatible spinel LiCoO2 coating layer on the particle surface. Detailed local structure and first principles investigations reveal that the shape and orientation of the octahedral layer in the host lattice are modified. Accordingly, a two‐band oxygen redox behavior is triggered in the ligand‐orientation‐regulated Li‐rich cathode, leading to enhanced reversibility, and thus, remarkably improved capacity and voltage retention over cycling. This study highlights the importance of controllable ligand orientation, carving a new path for the development and design of Li‐rich cathodes in the future.

Unblocking Oxygen Charge Compensation for Stabilized High‐Voltage Structure in P2‐Type Sodium‐Ion Cathode

“…Note that the oxygen charge compensation observed in the D-NNM should be distinguished from the oxygen redox behavior in the Li-/Na-rich systems. [4,12,58] In the oxygen redox reaction, the electrons extracted from oxygen will flow to an external circuit and account for extra capacity. By contrast, the XPS results in this study reveal that the appearance of O n− (n < 2) at high voltage is accompanied by the reduction of Ni ions, so the electrons from the oxygen transfer to Ni ions for charge compensation instead of going to the external circuit for capacity.…”

“…[1] Among the currently existing energy storage technologies, lithium-ion batteries (LIBs) are widely applied in portable devices and preferred for powering nextgeneration electric vehicles (EVs). [2][3][4] Despite almost 30 years of commercial success, nevertheless, concerns have recently arisen about the shortage of Li resource and potentially rising costs. [5,6] With this regard, searching for alternative energy storage chemistries lies at the very heart of global concerns nowadays.…”

Enhancing the Electrochemical Properties of Ti-Doped LiMn2O4 Spinel Cathode Materials Using a One-Step Hydrothermal Method

“…Characterized by high energy density and high cycle life, lithium-ion batteries have attracted considerable attention. 1 − 6 Compared to other cathode materials, spinel LiMn 2 O 4 has the advantages of abundant resources, low cost, safety, nontoxicity, environmental friendliness, and superior performance. 7 , 8 However, its commercial applications are limited due to issues with rapid capacity decay, which is mainly caused by Mn 3+ ion Jahn–Teller distortion.…”

Enhancing the cycle stability of Zr-doped LiNi0.83Co0.12Mn0.05O2 by co-precipitation

“…The larger the value of ΔV is, the higher the degree of polarization is, the worse the reversibility of the electrochemical reaction becomes. Improving the reversibility of the redox reaction can be achieved by adjusting the geometry of the surface ligands [36]. For cathodes with different doping levels, when Zr is doped, the ΔV value is reduced, demonstrating that the degree of polarization is reduced and the irreversibility of the lithium ion migration is decreased.…”