Among them, lithium iron phosphate and lithium manganese oxide materials have limited room for technological breakthroughs in basic research, and their energy density and key technical indicators are approaching their application limits. From the perspective of technological progress, ternary materials, due to their advantages such as high energy density, long cycle life, and high reliability, are gradually becoming the mainstream cathode materials for power lithium batteries.
Driven by the rapid development of lithium-ion batteries and their downstream industries, the sales of lithium-ion battery cathode materials have surged. In 2016, global sales of lithium-ion battery cathode materials reached 317,400 tons, a year-on-year increase of 42.1%, with a compound annual growth rate of 32.17% from 2011 to 2016. In terms of application structure, the lithium-ion battery cathode material market can be subdivided into the small-scale lithium-ion battery cathode material market and the power lithium-ion battery cathode material market. Small-scale lithium-ion battery cathode materials mainly include lithium cobalt oxide, ternary materials, and lithium manganese oxide, while power lithium-ion battery cathode materials mainly include lithium manganese oxide, lithium iron phosphate, and ternary materials.
Lithium-ion battery cathode material production process
The performance of the cathode material in a lithium-ion battery directly affects the battery's performance, and its cost directly determines the battery's overall cost. The industrial production of cathode materials involves numerous steps and complex synthesis routes, requiring strict control over temperature, environment, and impurity content. Important cathode materials include lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials.
The calcination technology utilizes a novel microwave drying technique to dry lithium-ion battery cathode materials. This solves the problems of long drying times, slow capital turnover, uneven drying, and insufficient drying depth associated with conventional lithium-ion battery cathode material drying technologies. Specific features include:
1. Using microwave drying equipment for lithium-ion battery cathode materials, the process is quick and efficient, completing deep drying in just a few minutes, achieving a final moisture content of over one-thousandth;
2. The drying process is uniform, resulting in high-quality dried products;
3. Lithium-ion battery cathode materials are highly efficient, energy-saving, safe, and environmentally friendly;
4. It has no thermal inertia, and the instantaneous heating is easy to control. Microwave sintering of lithium-ion battery cathode materials has the characteristics of fast heating rate, high energy utilization rate, high heating efficiency, and safety, hygiene and no pollution. It can also improve the uniformity and yield of products, and improve the microstructure and performance of the sintered materials.
General preparation methods for lithium-ion battery cathode materials
1. Solid-phase method
Generally, lithium salts such as lithium carbonate are ground and mixed with cobalt or nickel compounds, followed by a sintering reaction. The advantages of this method are its simple process flow, readily available raw materials, and its widespread research, development, and production in the early stages of lithium-ion battery development; foreign technology is relatively mature. The disadvantages are that the resulting cathode material has limited capacity, poor uniformity of raw material mixing, poor performance stability of the prepared material, and poor batch-to-batch quality consistency.
2. Complexation method
The complexation method involves first preparing a complex precursor containing lithium ions and cobalt or vanadium ions using organic complexes, followed by sintering. The advantages of this method are molecular-scale mixing, good material uniformity and performance stability, and higher cathode material capacity compared to the solid-state method. It has been tested as an industrial method for lithium-ion batteries abroad, but the technology is not yet mature, and there are few reports on it in China.
3. Sol-gel method
The method for preparing ultrafine particles, developed in the 1970s, is used to prepare cathode materials. This method combines the advantages of the complexation method and significantly improves the capacitance of the prepared electrode materials. It is a rapidly developing method both domestically and internationally. The disadvantages are high cost and the fact that the technology is still in the development stage.
4. Ion exchange method
The ion-exchange method for preparing LiMnO2 has yielded a reversible discharge capacity of 270 mAh/g, making this method a new research hotspot. It features stable electrode performance and high capacity. However, the process involves energy-intensive and time-consuming steps such as solution recrystallization and evaporation, which means it is still far from practical application.
In the field of lithium-ion battery cathode materials, even the smallest technological innovation can trigger a new round of market expansion. Chinese companies should strengthen their research and development of key cathode material technologies to achieve international leadership, enhance their core competitiveness, and gain an advantage in international competition.
