Hollow spherical sodium nickel manganate and preparation method thereof, sodium ion battery positive electrode, and sodium ion battery

Abstract

The present invention provides a hollow spherical sodium nickel manganate and a preparation method thereof, a sodium ion battery positive electrode, and a sodium ion battery, which belongs to the technical field of sodium ion batteries. The present invention provides a hollow spherical sodium nickel manganate having a particle diameter of 2.5-3.5 micrometer, a wall thickness of 0.5-1.0 micrometer,and a smooth outer surface. A chemical composition of the hollow spherical sodium nickel manganite is NaxNiyMnzO2, where x:y:z=2:1:3. The sodium nickel manganate provided by the present invention hasa hollow spherical structure with regular morphology and high crystallinity, which is beneficial for sodium ions to rapidly enter a solid phase medium from the surface, a diffusion path between solidphase particles is shortened. The sodium ion battery assembled from the sodium ion battery positive electrode obtained by using the hollow spherical sodium nickel manganate as a raw material has excellent cycle stability and rate performance.

Description

Technical field [0001] The invention relates to the technical field of sodium ion batteries, in particular to a hollow spherical sodium nickel manganate and a preparation method thereof, a sodium ion battery positive sheet and a sodium ion battery. Background technique [0002] In recent years, with the rapid development of electronic equipment, power tools, and low-power electric vehicles, research on energy-efficient, resource-rich and environmentally friendly energy storage materials is a necessary condition for human society to achieve sustainable development. Lithium-ion batteries are widely used in various electronic devices due to their advantages of high energy density, long cycle life, high working voltage, no memory effect, small self-discharge, and wide operating temperature range. However, with the widespread application of lithium-ion batteries, the consumption of metal lithium has been accelerated, and lithium is facing a shortage of resources. The research and dev...

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Problems solved by technology

[0004] Sodium nickel manganate has a high theoretical specific capacity and has great potential to be a cathode material for sodium-ion batteries, but it faces a serious capacity fading problem, mainly due to the reversible intercalation / extraction of sodium ions during charge and discharge. , causing the collapse of the crystal structure

There are literatures (Manikandan P, Ramasubramonian D, Shaijumon MM. Electrochimica Acta, 2016, 206:199-206.) proposed to use nickel and manganese acetate to form a gel, and then mix it with sodium salt and directly react at high temperature to obtain Na 0.5 Ni 0.25 mn 0.75 o 2 , has a typical P2-type layered structure, but its cycle life is short and its capacity fades seriously. The main reason is that nickel-manganese has different solubility products. The nickel-manganese in the original solution cannot precipitate according to the stoichiometric ratio, resulting in The stoichiometric ratio of nickel-manganese elements deviates from the design value; the patent CN105692721A uses the hydroxide precipitation of nickel and manganese mixed with sodium salt, and calcines at 750-900°C for 4-24 hours to obtain layered Na x Ni 0.5+ y mn 0.5-y o 2 Material (x=0.9~1.1, y=0~0.2); patent CN103922427A utilizes nickel, manganese compound and complexing agent reaction, has prepared a kind of complex metal oxide Na 2 / 3 Ni 1 / 3 mn 2 / 3 o 2 , although the existing technology has improved the cycle stability of sodium nickel manganese oxide by changing the preparation method, the improved cycle performance is still relatively limited, and the preparation process is complicated

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