P2-type layered oxide cathode materials for sodium-ion battery

Abstract

Sodium-ion batteries (SIBs) have collected major interest recently and are believed a possible replacement for lithium-ion batteries (LIBs). SIBs have a price-benefit over LIBs for two major causes. Sodium, not like Lithium, does not make alloy with Aluminium in the region of anodic potential. Therefore, anodic current collector copper is utilized as the in LIBs, can be changed with the less expensive Aluminium for SIBs. Another reason is that reserves of sodium are more extensive and plentiful than Li-based raw materials. One of the encouraging groups for cathode materials is layered metal oxides, NaxTMO2 (TM = transition metal). In this group, there are various dominant subclasses, which are specified based on the coordination of the sodium ions between the layers of TM and oxygen. Following the terminology proposed by Delmas et al., in P-phase materials, sodium ions (Na+ ) is coordinated by oxygen in prismatic way, however in O-phase materials, the coordination is octahedral manner. Variations in filling, i.e., layers shifting comprised of edge-sharing MO6-octahedra opposed to one another, are shown by digits. In a P2-structure, two layers of MO6- octahedra need to be represented in the unit cell to precisely explain the structure. The earliest experiments on insertion procedures into these layered oxides have been performed in the 1980s. Newly, especially P2-phase materials have obtained significant attention since their good capacity and cycling stability. Transition metal oxides are examined in terms of their opportunity as cathode materials for SIBs. The most recent advancement in research in the several structures of the layered oxide cathode material in SIBs are charted. Furthermore, their cost, concerns and electrochemical performance estimated in detail along with a brief viewpoint on prospects. P2 phase Na0.67Ni0.15Fe0.15Mn0.7O2 layered oxide synthesized by sol gel methods and have shown well grown morphology at 850 oC and phase have been confirmed by X-ray diffraction. Electrochemical performance of the as prepared material has been measured by Autolab instrument in three electrode system and have shown specific capacity of 353.5 mAh/g at 0.002 V/s scan rate and 52.17 mAh/g at 0.1 V/s from cyclic voltammetry. From GCD it shows 289.95 mAh/g at 1 mA current and 139.13 mAh/g at 3 mA current in 1.38 V voltage range. The aluminium doped layered oxide material have performed well in electrochemical analysis by three electrode system. The different phase of layered transition-metal oxides (NaxTMO2; TM= Mn, Ti, Co, Ni, Fe, Al, V, Cr, and a grouping of various elements) show good capacity, structural stability, Na+ ion conductivity, and cyclic number, which make them a first choice for the cathode materials of SIBs. In this work, the structural evolution, and recent improvement and certain challenges of NaxTMO2 cathodes for SIBs are summarized. This work proposes to give a reference for the evolution of many layered transition-metal oxide (LTMOs) cathode materials for SIBs, mainly for their promising commercialization.