Restraining Oxygen Loss and Suppressing Structural Distortion in a Newly Ti-Substituted Layered Oxide P2-Na_0.66Li_0.22Ti_0.15Mn_0.63O₂

Abstract

Anionic redox reveals to be a promising strategy to effectively improve the energy density of layered metal oxide cathodes for sodium-ion batteries. However, lattice oxygen loss and derived structural distortion severely hinder its practical application. Herein, combined with anionic and cationic redox activities, we developed a layered structure P2-type Na0.66Li0.22Ti0.15Mn0.63O2 cathode, delivering an initial discharge capacity of 228 mAh g–1 and highly reversible structural evolution as well as improved cyclability. On the basis of comprehensive comparison with Ti-free P2-Na0.66Li0.22Mn0.78O2, both oxygen-related negative behaviors (irreversible O2 evolution and superoxo-related parasitic production) and Mn-related Jahn–Teller distortion have been effectively restrained by simultaneously suppressing both oxygen loss and the participation of Mn4+/Mn3+ redox. Not limited to discovering excess capacity derived from anionic oxidation up charging, our findings not only highlight an effective strategy to stabilize anionic and cationic redox activities but also pave the way for the further improvement of Na-deficient layered materials for high-energy sodium-ion batteries.

Lithium‐Substituted Tunnel/Spinel Heterostructured Cathode Material for High‐Performance Sodium‐Ion Batteries

“…[22,23] Moreover, Li is also widely used to improve other cathode materials for SIBs. [24,25] It has been reported that Li + substitution can strengthen the crystal structure through strong LiO bonding, disrupt long-range MnMn interaction/contact, and hinder the disproportionation of Mn 3+ . Doping alkali metal sites and the transition metal layer of cathode materials with Li ions can improve the performance of the cathode materials.…”

“…[26,27] While Li-ions that are introduced into oxide cathodes maintain a single-phase structure, their electrochemical performance is limited. [25] In recent work, the heterostructures of tunnel-layered and P2-O3 intergrown cathode materials have attracted great interest owing to their synergistic effects. [28,29] The bi-phase structures provide stable crystal frameworks and accelerate the diffusion of electrons and Na + .…”

High‐Voltage Oxygen‐Redox‐Based Cathode for Rechargeable Sodium‐Ion Batteries

“…In situ or operando Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) become important tools in identifying the formation of peroxolike species (O 2 n− ). [14,15] Yang and Devereaux [16] highlighted the importance of using resonant inelastic X-ray scattering (RIXS) to identify the activity of lattice oxygen in oxide materials. From the above facts, it is considered that combination of the above-mentioned characterization tools with theoretical thermodynamic prediction may provide more reliable results to understand the oxygen redox chemistry.The oxygen redox reaction has also been extensively investigated in SIBs to achieve additional capacity.…”

In-situ/operando characterization techniques in lithium-ion batteries and beyond

“…The gas release process was even smelled in all-solid-state Li-ion batteries by means of attenuated total reflection infrared spectroscopy (ATR-IR), isotopic labeling and DEMS [186]. Bartsch [187] Copyright 2019 American Chemical Society); (c) schematic description of the in-situ lithium-ion pouch cell with gas port and the collected data of gas evolution at various voltage states (Reproduced with permission from ref. [182] Copyright 2020 Schmiegel, Horsthemke, Winter and Placke); (d) in-situ DEMS of the charge/discharge process at a NPG cathode of Li-O 2 system in different cycles (Reproduced with permission from ref.…”