A perovskite mgnbo3 magnesium-ion battery anode material synthesized by selective crystallization controlled by electric field

Abstract

The invention provides a perovskite MgNbO3 magnesium ion battery negative electrode material synthesized through electric field regulation and control selective crystallization and a preparation method thereof. The material is characterized in that the crystallization characteristics of crystals with the lattice defects are changed by applying the electric field in the specific direction during high-temperature solid-phase reaction are utilized; particles with column-shaped appearances grow in the electric field directions; meanwhile, through the non-uniform crystallization on the surfaces of the particles with the column-shaped appearances, sintering agents are nonuniformly adhered on positions with the great surface curvature radius to form the continuous porous appearance. The appearance is favorable for reducing the grain boundary resistance and the electronic migration resistance; the oxidation-reduction reaction speed and the magnesium ion migration capability in the lattices and electrolyte are accelerated; certain structure rigidity is realized; the buffer is formed for the material volume change in the charging and discharging process, so that the high-performance magnesium ion battery negative material is formed.

Description

technical field [0001] The invention relates to the technical field of a method for manufacturing a high-performance perovskite composite magnesium-ion battery negative electrode material. Background technique [0002] Lithium-ion secondary batteries have the absolute advantages of high volume, weight-to-energy ratio, high voltage, low self-discharge rate, no memory effect, long cycle life, and high power density. Currently, the global mobile power market has an annual share of more than 30 billion US dollars and Gradually grow at a rate of more than 10%. Especially in recent years, with the gradual depletion of fossil energy, new energy sources such as solar energy, wind energy, and biomass energy have gradually become alternatives to traditional energy sources. Among them, wind energy and solar energy are intermittent, and a large amount of energy is used simultaneously to meet the needs of continuous power supply. Energy storage batteries; urban air quality problems caus...

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Problems solved by technology

However, it is still very difficult to take into account the rate performance and cycle capacity retention performance of the material.

The main reasons are as follows: 1. When the redox reaction occurs, the electrode material should have fast lithium ion intercalation and deintercalation and electronic conduction, that is, it should have good electronic conductivity and ion conductivity at the same time. Many negative electrode materials have high However, it is an electronic insulator, and some negative electrode materials are good electronic conductors, but the diffusion capacity of lithium ions is weak, which greatly increases the polarization of the battery; 2. Many electrode materials are intercalated with lithium ions and There is a large volume change during the deintercalation process, resulting in the breakage of electrode material particles and the loss of effective electrode materials during the cycle. The large volume change also brings about the transformation of the material lattice during the charging and discharging process to produce a second phase. seriously affect the performance of the battery

3. Lithium battery negative electrode material with conversion reaction mechanism, the electronic insulation of the reaction product lithium compound seriously affects the reversibility of the material

ABOs 3 When the alloy reaction is carried out, the oxide can react with two metals, which may produce alloy solid solutions in various phases. Due to the interaction of bimetals, it may also produce electrochemical characteristics that are completely different from those of single metals. Therefore, ABOs 3 Type oxide has the potential to become a high-performance magnesium-ion battery anode material, which may provide close to or more than 300mAh.g -1 The specific capacity, the volume change of the material that magnesium ions enter or exit is also small; however, the research and development of this material in magnesium ion batteries is basically blank

And its main problem is: 1, ionic conductivity and electron conductivity are low; 2, the product magnesium oxide after conversion reaction is electronic insulator and its magnesium ion diffusion activation energy is also higher, causes greater electrochemical polarization; 3. The synthesis temperature is high, which is easy to cause the growth and agglomeration of grains

[0014] In response to these problems, changing the morphology of the material can alleviate these problems to a certain extent. For example, reducing the particle size of the material to the nanometer scale can reduce the diffusion path of magnesium ions, shorten the diffusion time of magnesium ions, and improve the kinetics of the material. Performance; too small a particle size can easily cause difficulties in electronic conduction between particles; the same agglomeration between particles or too large particles can easily cause electrolyte penetration difficulties between particles, slow migration of magnesium ions, etc.

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