Several cutting-edge technologies of lithium -Lithium - Ion Battery Equipment

Several cutting-edge technologies of lithium batteries -Lithium - Ion Battery Equipment

1. All-solid-state lithium battery

The current commercial lithium battery electrolyte is liquid, so it is also called liquid lithium battery. In simple terms, an all-solid-state lithium battery means that all components in the battery structure exist in a solid state, replacing the liquid electrolyte and separator of traditional lithium batteries with solid-state electrolytes.

Compared with liquid lithium batteries, all-solid-state electrolytes have the following advantages: high safety/excellent thermal stability, long-term normal operation at 60-120 °C; wide electrochemical window, can reach more than 5V, can Matching high-voltage materials; only conducts lithium ions but not electrons; simple cooling system, high energy density; can be used in the field of ultra-thin flexible batteries. However, the disadvantages are also obvious: the ionic conductivity per unit area is low, the specific power is poor at room temperature; the cost is extremely expensive; the industrial production of large-capacity batteries is difficult.(Lithium - Ion Battery Equipment)

The performance of electrolyte materials largely determines the power density, cycle stability, safety performance, high and low temperature performance, and service life of all-solid-state lithium batteries. Solid electrolytes can be divided into two categories: polymer electrolytes (generally based on mixtures of PEO and lithium salt LiTFSI as electrolyte substrates) and inorganic electrolytes (such as oxides and sulfides). All-solid-state battery technology is recognized as the next-generation innovative battery technology for key development. I believe that in the near future, the technology will become more and more mature, and these problems can be solved.

2. Ternary material battery with high energy density

With the pursuit of battery energy density, ternary cathode materials have attracted more and more attention. The ternary cathode material has the advantages of high specific capacity, good cycle performance and low cost, and generally refers to the layered structure of nickel-cobalt lithium manganate material. By increasing the battery voltage and the nickel content in the material, the energy density of the ternary cathode material can be effectively improved.

Theoretically speaking, the ternary material itself has the advantage of high voltage: the standard test voltage of the half-cell of the ternary cathode material is 4.35V, at this voltage, ordinary ternary materials can show good cycle performance; the charging voltage When it is increased to 4.5V, the capacity of symmetrical materials (333 and 442) can reach 190, and the cycle performance is not bad, but the cycle performance of 532 is worse; when charged to 4.6V, the cycle performance of the ternary material begins to decline, and the flatulence phenomenon becomes more and more serious. . At present, the factor that restricts the practical application of high-voltage ternary cathode materials is that it is difficult to find a high-voltage electrolyte that matches it.

Another method to improve the energy density of ternary materials is to increase the content of nickel in the material. Generally speaking, high nickel ternary cathode materials refer to the mole fraction of nickel in the material greater than 0.6, such ternary materials have high specific capacity and It has the characteristics of low cost, but its capacity retention rate is low, and its thermal stability performance is poor. The performance of this material can be effectively improved through the improvement of the preparation process. The micro-nano size and morphology have a great influence on the performance of high-nickel ternary cathode materials. Therefore, most of the current preparation methods focus on uniform dispersion to obtain spherical particles with small size and large specific surface area.

Among many preparation methods, the combination of co-precipitation method and high temperature solid phase method is the mainstream method. First, the co-precipitation method is used to obtain a precursor with uniform mixing of raw materials and uniform particle size. Then, ternary materials with regular surface morphology and easy process control are obtained by high temperature calcination. This is also an important method used in industrial production. Compared with the co-precipitation method, the spray-drying method has a simpler process and a faster preparation speed, and the morphology of the obtained material is no less than that of the co-precipitation method, which has the potential for further research. The shortcomings of high nickel ternary cathode materials such as cation mixing and phase transition during charge and discharge can be effectively improved by doping modification and coating modification. While suppressing the occurrence of side reactions and stabilizing the structure, improving electrical conductivity, cycling performance, rate performance, storage performance.



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