Boehmite vs alumina-lithium battery coating material

Diaphragm is one of the four major components of lithium ion battery, which plays the role of isolating the positive and negative poles, preventing the contact of the positive and negative poles from short circuit and providing channels for lithium ions to pass through.  At present, in order to better match the safety and performance requirements of the power battery, the application of coated diaphragm in power battery has gradually become the mainstream.

Introduction of coating materials for lithium batteries  

The current market coating material types are mainly divided into inorganic coating, organic coating, organic + inorganic coating three ways. 

Boehmite  

Boehmite (AlOOH) can retain its mesoscopic morphology during calcination, so it can be used as a precursor for preparing nano-alumina with different morphologies.  In addition, AlOOH can be used as a ceramic material, catalyst and carrier material, membrane coating for lithium batteries and optical materials.  

As a coating material for lithium battery, boehmite is mainly used for the coating of lithium battery cell diaphragm and electrode plate.  Coating the lithium battery cell diaphragm can improve the heat resistance of diaphragm, enhance the puncture resistance of diaphragm, improve the safety performance of lithium battery;  The coating can avoid the burr of positive electrode material from penetrating the diaphragm during the cutting process, improve the safety performance of lithium battery, improve the battery production process, and improve the energy density.  In addition, benefiting from the characteristics of low magnetic foreign body content, low water absorption, low specific gravity, low Mohr hardness, boehmite can also help improve the battery rate and cycle performance, improve the cell yield, and reduce battery self-discharge in the process of use, is an important material to improve the safety and reliability of lithium battery.  

Alumina powder  

Alumina is abundant in nature and has excellent chemical inertia, thermal stability and mechanical properties.  As a ceramic coating for lithium battery diaphragm, it has the following advantages:

The alumina coating has high temperature resistance and can maintain the complete form of diaphragm at 180℃;  

The alumina coating can neutralize the free HF in the electrolyte and improve the acid resistance and safety performance of the battery;  

Nanocrystalline alumina can form solid solution in lithium battery to improve the doubling and cycling performance;  

Nano-alumina powder has good wettability and certain liquid absorption and retention ability;  

Alumina coating can increase the micropore tortuosity, self-discharge lower than ordinary diaphragm.  

The use permeability of boehmite in inorganic coating materials is expected to continue to increase