Lithium battery analysis: 2021 polymer lithium battery market penetration rate is expected to increase

According to the classification of electrolyte materials, lithium-ion batteries can be divided into liquid lithium-ion batteries and polymer lithium-ion batteries. Due to the relatively high cost of polymer lithium batteries, its market share is relatively low. Liquid lithium batteries are widely used in the field of power vehicles. In the field of power vehicle applications, polymer lithium batteries are in the process of commercialization. With technological breakthroughs and the realization of large-scale production, the cost of polymer lithium batteries is expected to decrease rapidly, and the penetration rate is expected to further increase.

Major listed companies in the lithium battery industry: Ningde Times (300750. SZ), Guoxuan High-Tech (002074. SZ), Yiwei Lithium Energy (300014. SZ), Desay Battery (000049. SZ), Narada Power (300068. SZ) Wait.

The core data of this article: battery thickness, weight, capacity, internal resistance, cycle times, permeability, etc.

Lithium ion batteries can be divided into liquid lithium ion batteries and polymer lithium ion batteries

The electrolyte used in lithium-ion batteries is generally composed of an organic solvent and a lithium salt dissolved in it. The organic solvents currently used are mainly carbonate-based compounds (divided into two categories: PC-based and EC-based).

Lithium ion batteries can be divided into liquid lithium ion batteries and polymer lithium ion batteries. Polymer lithium ion batteries are developed from liquid lithium ion batteries. In addition to organic solvents and lithium salts, polymer electrolytes also include pure solid/gel type polymer.

Chart 1: Graphs of liquid lithium-ion batteries and polymer lithium-ion batteries

The difference between the two types of battery materials is mainly the electrolyte

Since the positive and negative materials used in liquid lithium-ion batteries are the same as those used in polymer lithium-ion batteries, the main difference lies in the electrolyte. The electrolyte of liquid lithium-ion batteries is liquid, and the electrolyte of polymer lithium-ion batteries is semi-solid colloid or pure solid.

The difference of the electrolyte material has an impact on the material of the two shells, the selection of the diaphragm and the current collector. Compared with liquid lithium batteries, the outer packaging of polymer lithium batteries uses a thinner aluminum film, which is thinner than steel shells and aluminum shells. However, in the case of the same battery thickness, the material cost of polymer lithium batteries is similar to that of liquid lithium batteries. Close, but the process cost is much higher than the latter;

In the polymer lithium battery, the electrolyte plays the dual function of the diaphragm and the electrolyte: 1) Separate the positive and negative materials like a diaphragm, so that self-discharge and short circuit will not occur inside the battery; 2) Play the role of the electrolyte, in the positive Lithium ions are conducted between the negative electrodes.

Chart 2: Comparison of liquid lithium-ion battery and polymer lithium-ion battery materials

The relatively low share of polymer lithium batteries

The thickness of the polymer lithium battery can theoretically reach 0.5mm, which meets the requirements of the mobile phone for the battery thickness of 4mm and below; compared with the liquid lithium battery, the polymer lithium battery has a lighter weight under the same capacity and the capacity under the same size. Higher; the internal resistance of the polymer cell can reach 35mΩ or less, which greatly reduces the self-consumption of the battery.

Compared with liquid lithium batteries, polymer lithium batteries have higher energy density, more flexibility in customization, lighter weight, and higher safety. However, due to its relatively high cost relative to liquid lithium batteries, the market share of polymer lithium batteries is relatively low.

Chart 3: Comparison of polymer lithium battery and liquid lithium battery

Two types of battery applications continue to expand

Liquid lithium-ion batteries are widely used in 3C electronic products, electric vehicles, industrial markets and other fields. By virtue of their cost-effective advantages, they are used in portable computers, video cameras, large-scale energy storage and other markets. With the improvement of the performance of liquid lithium-ion batteries, its application fields are also expanding, such as electric tools, electric toys, telephones and household appliances.

The polymer lithium battery has the characteristics of thinness, which can meet the needs of the product. Polymer lithium-ion batteries are mainly used in mobile phones, Bluetooth headsets, notebook computers, etc. As its technology continues to mature and prices continue to fall, the potential application areas of polymer lithium-ion batteries include electric vehicles, small radios and walkie-talkies, electric bicycles, and military fields.

According to high-tech lithium battery data, the penetration rate of polymer lithium batteries in the field of power vehicles is low. In 2020, liquid lithium batteries (cylindrical and square batteries) will account for 90.5% of the shipments in the field of power vehicles. In the field of power vehicle applications, polymer lithium batteries are in the process of commercialization.

Chart 4: Application areas of polymer lithium batteries and liquid lithium batteries

The penetration rate of polymer lithium-ion batteries is expected to increase further

At present, most of the polymer lithium-ion batteries are in the laboratory pilot stage, and their costs are still not comparable to liquid batteries. However, with technological breakthroughs and the realization of large-scale production, their costs are expected to decrease rapidly. The polymer solid electrolyte based on PEO or PEO-like membrane is expected to accelerate the commercialization process, thereby driving the increase in the permeability of polymer lithium-ion batteries.