Lithium-ion batteries belong to the small sealed secondary battery market and compete with Ni-Cd batteries and Ni-MH batteries in multiple application fields. Lithium-ion batteries can be made into cylindrical, square and flat structures. Cylindrical and prismatic batteries use wound pole groups, and the battery case can withstand external pressure on the positive electrode, separator, and negative electrode. A slightly lighter polymer battery uses the adhesive properties of polymer electrolytes to bond the positive and negative electrodes together. Therefore, there is no need for external pressure to maintain the connection between the electrodes, and a light-weight polymer aluminum-plastic packaging bag can be used to replace the heavier metal casing. The batteries of these three structures use the same chemical materials.
Lithium-ion batteries are extremely competitive in the market. Driven by the application of portable electronic devices (such as notebook computers and mobile phones), the market for lithium-ion batteries has grown astonishing. In the 15 years from 1991 to 2006, the sales and production of lithium batteries both showed double-digit growth.
In 1995, the price of an 18650 battery was $8, and by 2006, the price of an 18650 battery with a capacity of 2.6A·h was only $4. In this period, the battery capacity has more than tripled, but the price has dropped by 50%. Lithium-ion battery manufacturers use process improvements in battery design and the application of new carbon materials in the anode to improve battery performance, and reduce battery costs through high-speed automated production. Due to the introduction of new technologies and new application development, the lithium battery market is expected to continue to grow.
Japanese lithium-ion battery manufacturers (Sanyo, Sony, Panasonic) are in a leading position, and Chinese lithium-ion battery manufacturers (BYD, Lishen) and South Korean lithium-ion battery manufacturers (Samsung, LG Chem) have certain competitiveness. Although the United States (or Europe) has a large application market for lithium-ion batteries as equipment power supplies, there is no important lithium-ion battery manufacturer. In the United States, manufacturers of lithium-ion batteries are limited to a few companies, mainly supplying small medical and military applications.
Since the advent of lithium-ion batteries, the basic development of lithium-ion battery materials and manufacturing processes has been mainly carried out from 1991 to 2002. During this period, problems were constantly discovered and solutions were found. The maturity of lithium-ion battery materials, battery design and manufacturing equipment reached a high level. These technical foundations are the expansion of lithium-ion batteries in the next ten years. And development provide solid support. From the perspective of battery technology, 18650 batteries with a maximum capacity of 2.5 to 2.6A·h can be made using materials that existed in 2002. While battery capacity and energy storage performance are improved, new materials are needed to maintain battery safety.
Since 2003, the market application of lithium batteries has undergone new changes. The continuous improvement of capacity and performance is partly due to the fiercer competition between notebook computers and mobile phone applications, which requires the introduction and development of higher capacity and higher performance positive and negative materials. Some high-capacity, safer cathode materials, such as LiMn0.3 Co0.3Ni0.5O2 and LiMn0.5Ni0.5O2, have been developed and gradually applied in production. At the same time, a new type of lithium alloy anode material has been developed. These materials can increase the capacity of the 18650 battery to more than 2.6A·h, and will reach 3.0A·h in the future.
On the other hand, applications such as automobiles and power tools do not require a significant increase in the energy density of lithium-ion batteries, but emphasize lower costs and higher power. These applications also require new positive and negative materials to meet the low-cost, high-rate market demand. In 2003, Valence Technology Corporation and A123 Corporation successively introduced a new type of cathode material LiFePO4 to the market. The lithium-ion battery of this new material is mainly used in electric tools.