A negative electrode material for double perovskite lithium-ion batteries synthesized by selective crystallization controlled by electric field and its preparation method

Abstract

The invention discloses a double-perovskite lithium-ion battery anode material synthesized through electric field regulated selective crystallization and a preparation method of the anode material. The anode material is characterized in that the composition of the anode material is Na0.8Ba0.2Y0.9Li0.1Co0.9Zn0.1Nb0.9Mn0.1O6. The crystallization characteristic of crystals with lattice imperfection is changed by use of an applied electric field in the specific direction in a high-temperature solid-phase reaction during preparation, and cylindrical particles are formed through growing in the electric field direction; meanwhile, parts, with high surface curvature radiuses, of cylindrical particles unevenly adhere to a sintering aid to partially be adhered into continuous porous morphology. The morphology is beneficial to reduction of crystal boundary resistance and electron transfer resistance, increases the lithium-ion migration capacity and the redox reaction rate and has certain structure rigidity to form buffer for volume change; the lithium-ion battery anode material with high performance is formed through Na and Y co-occupation in position A, Ba doping in position Na, Li doping in position Y and Zn and Mn doping in position B.

Description

technical field [0001] The invention relates to the technical field of a method for manufacturing a negative electrode material of a lithium ion battery. 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 caused by automobile exhaust are becomi...

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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 The compound may become a high-performance lithium-ion battery anode material, which may provide close to or exceed 500mAh.g -1 The specific capacity, and its rate characteristics are superior to those of metal oxides, sulfides, phosphides, carbonates, and chlorides, and the volume change of the material that lithium ions enter or exit is also small; however, the research and development of this material is currently still in progress. very few

And its main problem is: 1, ionic conductivity and electronic conductivity are low; 2, the product lithium oxide after conversion reaction is electronic insulator and its lithium 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

[0010] 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 lithium ions, shorten the diffusion time of lithium ions, and improve the kinetics of the material. performance; too small a particle size can also 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 lithium ions and other problems; ion doping Doping is also an effective way to adjust the microstructure of the lattice and change the transport characteristics of lattice electrons and ions. However, the mechanism of ion doping or even multi-ion synergistic doping on the matrix is ​​very complicated, and the effect is often unpredictable.

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