Comparison of application performance between boehmite and alumina, Zhongtianli

China is the world's leading producer and consumer of lithium batteries. In 2019, China's power diaphragm shipment volume was 27.4 square meters (80% required coating), a year-on-year increase of 35.6%, and the total market volume of coating powder was around 10000 tons. The average annual growth rate from 2014 to 2019 is over 40%, and it is expected that the average annual growth rate of demand for separators for ternary battery power will be 30% in the next 3-5 years, with mainstream coating materials:

1. Aluminum oxide (80%);

2. Boehmite (15-18%);

3. Organic (3C, only reported in Japan and South Korea), etc

Development and Policy of New Energy Vehicle Technology: Expected Characteristics of Future Lithium Battery:

1. High energy density (140-175-200-0wh/kg);

2. Safety (membrane coated on both sides, ultra-thin to reduce internal resistance, lithium iron phosphate system uses coated membrane);

3. Stable charging and discharging;

Promote lithium battery separators to be lightweight and ultra-thin, coating materials to further refine particles from 0.7~1. to below 0. um, and ultra-thin films require below 0.5 um), with regular morphology and narrow particle size distribution. Zhongtianli Factory

The improvement of national safety performance standards for power and 3C batteries has made the encapsulation of power battery pack plates an inevitable choice for ternary batteries; NCA has a higher energy density compared to NCM, with 200-500 nanometers of boehmite as one of the aluminum sources; This has given rise to future market demand for electrode coating and positive electrode materials.

At present, separators for batteries such as power, consumer terminals, and microelectronics are mainly coated with 12um and 9um single-sided coatings (129+2-3.5). In the future, a new generation of 7um and 5um double-sided and single-sided ultra-thin coatings is required: the coating bulk density is 1.25-1.5g/m2, the pores are uniform, the coating thickness is 1-2um/surface, and the powder amount for 1m2 diaphragm coating is reduced from 3.5-5.5g to within 3g.

The contact mode between the substrate and the coating determines the development direction of the boehmite morphology of the coating material. The superior characteristics of li-ai-o channels over traditional skip channels have determined that encapsulation, NCA, and solid-state lithium-ion batteries will shift towards using aluminum materials with physical characteristics and chemical reactions of electrolytes, which will bring new opportunities for boehmite. Comparison of production processes for boehmite and alumina: chemical and mechanical methods

1. Mechanical method: disordered trend of morphology, mechanochemical reaction (the d value of XRD determines the grinding fineness), wide particle size distribution (small particles cannot be finely controlled).

2. Chemical method: The order and controllability of the reaction determine the regular morphology, controlled particle size, and narrow particle size distribution of boehmite.

Comparison of application performance between boehmite and alumina: The thermal performance of the membrane is equivalent to that of mainstream alumina, and the battery cycle efficiency is equivalent, but lower than that of high-purity alumina, which is equivalent to the domestic diaphragm coating market. Within 2-3 years, the situation of long-term coexistence of alumina in most lithium phosphate and 3C fields, a small portion of ternary battery fields (low energy density requirements), and boehmite in most ternary and high-end 3C fields will gradually form, At that time, Boehmite will occupy over 50% of the coating market (similar to South Korea and Japan) and over 80% of the coating market.