Review—Research Progress on Layered Transition Metal Oxide Cathode Materials for Sodium Ion Batteries

Abstract

The proportion of new energy power generation gets higher and higher, due to the depletion of fossil energy resources. However, new energy power is generally unstable, so that it is necessary to use energy storage batteries to balance the power peak and valley. Although lithium-ion batteries have been widely used in various fields, in particular for large-scale energy storage, the low abundance of lithium in the earth crust makes it untenable to meet the ever-intense future demand. Sodium ion batteries, which have similar energy storage mechanism to lithium-ion batteries, have attracted significant attentions due to their abundant raw material resources, low cost, and fairly high energy densities. Layered transition metal oxides are a class of the most promising cathode materials for sodium ion batteries, owing to their high theoretical specific capacities, good conductivity, and fast diffusion kinetics. In this paper, we conduct a comprehensive review of the electrochemical performance, structural characteristics, performance shortcomings and modification technologies about the O3- and P2-type layered transition metal oxide cathode materials. The application potentials of layered materials are summarized and analyzed, which provides a reference for the industry to select the most promising and practical layered cathode material for sodium ion batteries.

Validating the Structural (In)stability of P3- and P2-Na0.67Mg0.1Mn0.9O2-Layered Cathodes for Sodium-Ion Batteries: A Time-Decisive Approach

“…17 Generally, P-type layered oxides can be categorized into P2-and P3-type depending on the sodium-accommodating positions in the layered structure and the number of repetitions of TMO 2 slabs in the unit cell. 15 Hence, sodium ions at prismatic sites and in their diffusion pathway are quite different, thereby inferring different electrochemical kinetics between the two cases. The P3-type cathode exhibits a much better rate performance due to its larger sodium interlayer spacing, as denoted by the structure of oxygen stacking per unit cell (ABBCCA), wherein Na ions are sandwiched between the TMO 2 slabs through prismatic sites.…”

“…Na x TMO 2 (TM = Mn, Ni, and Co, among others) layered oxides are classified by two different structures, namely, O-(octahedral) type and P-(prismatic) type, which normally vary with the ratio of Na/TM and the Na + environment . The most common O3-type layered oxide, where the number indicates the repeated folds of the TMO 2 layers in a unit cell, can deliver a high reversible capacity. , However, the P-type layered oxide outperforms the O3-type layered oxide from the viewpoint of a high average working potential and rate performance, and thus, it has attracted research attention owing to its more open framework, which is more easily preserved during sodium extraction . Generally, P-type layered oxides can be categorized into P2- and P3-type depending on the sodium-accommodating positions in the layered structure and the number of repetitions of TMO 2 slabs in the unit cell .…”

An Advanced High‐Entropy Fluorophosphate Cathode for Sodium‐Ion Batteries with Increased Working Voltage and Energy Density

“…), especially those with a P2 type structure, [15] exhibit better cycle stability and rate performance due to the higher sodium-ion diffusion kinetics, and have been extensively studied. [16] At present, through the use of element doping, substitution, and interface modification suppression, the reversibility of layered transition mental oxide Impossible voltage plateau regulation for the cathode materials with fixed active elemental center is a pressing issue hindering the development of Na-superionic-conductor (NASICON)-type Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) cathodes in sodium-ion batteries (SIBs). Herein, a high-entropy substitution strategy, to alter the detailed crystal structure of NVPF without changing the central active V atom, is pioneeringly utilized, achieving simultaneous electronic conductivity enhancement and diffusion barrier reduction for Na + , according to theoretical calculations.…”

Research progress in O3-type phase Fe/Mn/Cu-based layered cathode materials for sodium ion batteries

“…Moreover, they have also received a lot of attention from researchers. 49 The electrochemical performance of some O3-type cathode materials is summarized in Table 1.…”