The synergy of dis‐/ordering ensures the superior comprehensive performance of P2‐type Na‐based layered oxide cathodes

Abstract

Two kinds of crystal orderings in layered oxides typically exhibit opposite influences on performances: Na+/vacancy ordering in alkali metal layers with an unfavorable effect on electrochemical performance and the cation ordering in transition metal layers with a positive effect on air stability. However, because the two kinds of orderings are associated with each other and often occur at the same time, it is difficult to achieve an excellent comprehensive performance. Herein, we propose a strategy of introducing a new cation ordering to construct the coexistence of Na+ disordering and transition metal ordering. An absolute solid‐solution reaction mechanism is realized in the Na+ disordered system, resulting in a superior cycling stability of 90.4% retention after 150 cycles and a rate performance of 82.7 mAh g−1 capacity at 10C, much higher than the original 81.3% and 66.4 mAh g−1. Simultaneously, the cation ordering strengthens the interlayer interaction and inhibits the insertion of water molecules from the air, ensuring stable lattice stability and thermostability after air exposure. The synergy of dis‐/ordering configuration provides new insights to design high‐performance layered oxide cathode materials for secondary‐ion batteries.

TheKspgap enabled precipitation transformation reactions from transition metal hydroxides to sulfides for alkali metal ion storage

“…The derived CuS nanostructure was further applied for storing alkali metal ions (Li + , Na + and K + ). [24][25][26][27][28][29] Among them, the SIB exhibits the best rate performance (Fig. 4a).…”

Unveiling the Origin of Air Stability in Polyanion and Layered‐Oxide Cathode Materials for Sodium‐Ion Batteries and Their Practical Application Considerations

“…The collected C 1s spectra contain C─C peak (284.8 eV), C─O peak (286.2 eV), and C═O peak (289.4 eV) as shown in Figure 2e, and the results are consistent with O1s spectra. In addition, the peaks corresponding to Ni 2+ (855.4 eV) and Ni 3+ (857.5 eV) [ 28 ] are observed in Ni 2p spectra for NFM materials (Figure 2f). For fresh NFM sample, the main existence of Ni element is Ni 2+ , and a certain amount of Ni 3+ exists in NFM to balance the total charge due to the existence of Mn 3+ (Figure S16, Supporting Information).…”

Promising Cathode Materials for Sodium-Ion Batteries from Lab to Application

“…Typical Na-based layered transition oxides, i.e., NaMO 2 (M = Ni, Co, Mn, Fe, Cr, V, etc. ), exist in different crystal structures denoted as P2, P3, O2, and O3 according to Delmas’ notation . O and P indicate the coordination environment of Na + , in which O represents the Na occupancy at the octahedron sites surrounded by six oxygens and P represents the Na occupancy at the center of prism sites surrounded by six oxygens.…”

“…However, the obtained PBAs present a random distribution of H 2 O and [M 2 (CN) 6 ] vacancies because of the rapid reaction between the hexacyanoferrate ligand and transition metal ions. 12 Additionally, the H 2 O in PBAs can be divided into three species: (i) H 2 O adsorbed on the surface, (ii) interstitial or zeolite H 2 O located at the alkali metal ion sites, and (iii) coordinated H 2 O chemically bonded with transition metals for the absence of [M 2 (CN) 6 ]. The H 2 O/vacancies in PBAs would cause lattice distortion and even structure collapse during (de)sodiation processes, leading to rapid capacity degradation.…”

“…9−11 Prussian blue and its analogs have the advantages of low cost, great rate performance, and adjustable working voltage, but the stubborn lattice water is difficult to remove and reduces the chemical stability and structural stability of the PBA material. 12 Effective improvement strategies have been proposed to address the shortcomings of different cathode materials, such as surface modification (isolation or coating), structural design, and lattice or interlayer modulation, in order to realize the high energy density, superior rate capability, and long service lifespan of SIBs (Figure 1).…”