How to restrain the gas of lithium titanate battery?

At present, there are three main solutions to inhibit gas expansion in lithium titanate batteries. The first is the processing modification of LTO negative electrode materials, including improved preparation methods and surface modification. Second, develop electrolytes that match the negative electrode of LTO, including additives and solvent systems; Third, improve battery technology.

(1) Improve the purity of raw materials and avoid the introduction of impurities in the manufacturing process. Imurity particles not only catalyze the classification of electrolytes to produce gas, but also greatly reduce the performance, cycle life, and safety of lithium batteries. Therefore, the introduction of impurities in batteries must be reduced as much as possible.

(2) The surface of lithium titanate is covered with carbon nanoparticles. The apparent reason for the formation of gas by the negative pole LTO is that the SEI membrane forms slowly and less, resulting in the phenomenon of flatulence with its lifetime. The study found that the establishment of an isolation layer between the interface between lithium titanate and electrolytes(such as the construction of a nanocarbon coating on the surface of lithium titanate(LTO/C), The solid electrolyte interface(SEI) membrane formed on the co-coating layer, on the one hand, reduces the contact area of the LTO material with the electrolyte and prevents the generation of gas.

On the other hand, carbon itself can produce a SEI membrane to make up for the lack of LTO, but also enhance the conductivity of LTO materials. The above research results are of great significance to solve the gas production behavior of lithium titanate batteries and promote the design and large-scale application and development of high-energy lithium titanate power cells.

(3) Improve the functionality of electrolytes. For the development of new electrolytes, many patents tend to use additives to promote the formation of dense SEI membranes on the surface of LTO to inhibit the occurrence of LTO and electrolyte interface side reactions. Certain electrolyte additives, such as fluorinated carbonates and phosphates, are conducive to the formation of stable SEI membranes on positive surfaces, reducing the dissolution of metal ions on positive surfaces, thereby reducing gas production.

Membrane-forming additives can also inhibit the amount of gas produced, The added membrane additives are lithium borate salt, Dingerjing or adienitrile, R-CO-CH = N2 structure compounds(where R is an alkyl or phenyl of C1 to C8), cyclic phosphate esters, phenyl derivatives, phenylacetylene derivatives, LiF additives, etc.. These film forming additives are conducive to the formation of SEI membranes on the surface of LTO, which to some extent inhibits the occurrence of flatulence.

(4) Positive polar surface coating. Covering a stable compound on a positive surface, such as aluminum oxide, can effectively inhibit the dissolution of metal ions. However, the over complicated coating will inhibit the deem bedding of lithium ions and affect the electrochemical properties of the materials.

(5) Improve the battery production process. Battery production, to control the environmental humidity, operation process water introduction. From the reason why the gas is produced, it can be seen that the water in the air reacts with the positive material to form lithium carbonate and accelerate the electrolyte decomposition to produce carbon dioxide. In addition, the lithium titanate material itself has a strong water absorption(which needs to be operated in a dry chamber). After the negative electrode absorbs water, it reacts with the PF5 generated by the reversible decomposition of the electrolyte to produce H2, so strict water control is essential.

The page contains the contents of the machine translation.