Three Directions of Battery Technology Breakthrough

Currently, there are three breakthrough directions in lithium battery technology: positive and negative electrode materials, electrolytes and diaphragms

Anode materials:

Lithium battery cathode materials mainly include lithium cobaltate, lithium manganate, nickel-manganese-cobalt ternary materials and lithium iron phosphate. Among them, lithium iron phosphate has several other materials do not have the potential advantages of cycle life, safety and material costs, is considered the ideal cathode material.

Cathode materials:

The cathode material is relatively low-tech and generally uses graphite as the cathode. However, despite the successful commercialization of graphite cathode materials, there are always some insurmountable weaknesses due to the use of carbon as the cathode. Because graphite forms a passivation film in the electrolyte, the film can transfer lithium ions but causes energy loss. In addition, when the battery is overcharged, metallic lithium precipitates on the surface of the graphite anode, which leads to a short circuit. As the temperature rises, the graphite anode in the lithium-embedded state will first react exothermically with the electrolyte, possibly producing flammable gas and burning. Therefore, graphite is not the most ideal anode material, and the search for non-carbon anode materials with better performance is an important issue in lithium-ion battery research.

Although various non-carbon anode materials have been widely studied, especially in recent years, nanostructured non-carbon anode materials such as tin composite oxides, titanium oxide compounds and titanate compounds, etc., these materials still have many problems that have not been solved and still cannot be used in large quantities, and need to continuously improve production routes and processes.

Electrolyte:

The electrolyte plays a role in conducting electrons between the positive and negative electrodes of lithium batteries, and is the guarantee for lithium-ion batteries to obtain high voltage, high specific energy and other advantages. Electrolyte is generally made of high purity organic solvent, electrolytic lithium salt, necessary additives and other raw materials, which are formulated in a certain ratio under certain conditions.

The main electrolytes used in lithium batteries are lithium perchlorate and lithium hexafluorophosphate. However, the battery made of lithium perchlorate is not good at low temperature, there is a risk of explosion, Japan and the United States have banned the use. While the battery made of lithium salt containing fluorine has good performance, no risk of explosion and high applicability.

Diaphragm:

The diaphragm plays a role in lithium batteries to prevent short-circuiting of the positive and negative electrodes, and provides a lithium ion transfer channel during the charging and discharging of lithium batteries. In short, the diaphragm is a porous plastic film. However, it directly affects the capacity, cycling performance and safety performance of the battery.

The high technical content of the diaphragm is due to the difficulty of its hole-making process. At present, the mainstream products of diaphragm internationally are single-layer polypropylene (PP) nanoporous film, single-layer polyethylene (PE) nanoporous film, PP/PE/PP three-layer composite nanoporous film and other types by transverse and longitudinal precision stretching.