The lithium-ion battery is a secondary battery (rechargeable battery), which mainly relies on the movement of lithium ions between positive and negative electrodes to work. During charging and discharging, Li+ intercalates and deintercalates between the two electrodes. During charging, Li+ is released from the positive electrode, inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; and the opposite is true during discharge.
- Electric vehicles: At present, light electric vehicles dominated by electric bicycles are showing a vigorous development trend, and lithium-ion batteries have begun to be used in some high-end models. In the development of electric vehicles, lithium-ion batteries have become mainstream. Lithium can form LiCoO2 or LiNiO2 with cobalt or nickel. This discovery paved the way for the birth of lithium-ion batteries. Lithium is combined with carbon (in the form of graphite or coke) to form a lithium-carbon compound (LixC as the negative electrode and lithium metal oxide as the positive electrode). Most lithium-ion battery anodes are layered oxides or lithium iron phosphates. Cheap lithium nickelate can also be used as a positive electrode, but its structure is more complicated, and its performance is similar to cobalt oxide. Manganese-based lithium-ion positive electrodes (such as LiMn2O4 or LiMnO2) are also used because of the low price of manganese metal, the wide range of materials and low toxicity. Lithium iron phosphate (LiFePO4) has become a new generation of cathode materials for electric vehicles due to its stable discharge characteristics and high-cost performance.
Figure 1. High capacity lithium manganate.
- Portable power: At present, electric appliances such as mobile phones, notebook computers, and miniature cameras that require portable power supplies have become an indispensable part of people's lives. Lithium-ion batteries have been widely used as portable power supplies. In this field, lithium cobalt oxide lithium ion batteries and lithium manganate lithium-ion batteries dominate. The positive electrode material of this type of lithium-ion battery is generally LiCoO2, LiFePO4, etc., the negative electrode material is generally graphite carbon, in which diethyl carbonate (DEC) is dissolved in LiPF6, LiBF4, etc. as the electrolyte.
Figure 2. Preparation of lithium iron phosphate.
- Energy storage: So far, for different needs in different fields, people have proposed and developed a variety of energy storage technologies to meet the applications. Lithium-ion battery energy storage is currently the most feasible technical route. Among the lithium-ion batteries, lithium iron phosphate batteries, lithium titanate batteries and lithium manganate batteries are mainly used in the field of smart grids. Lithium iron phosphate batteries have a relatively high energy density and strong endurance. And with the application of lithium iron phosphate cathode materials, the service life and safety of traditional carbon anode lithium-ion power batteries have been greatly improved, so that they can be first used in the field of energy storage. Lithium titanate batteries have a long cycle life, but they have relatively low energy density, weak endurance and relatively high price. Improving these shortcomings can enable lithium titanate batteries to be used for energy storage. Lithium manganate batteries have good rate performance and are relatively easy to prepare, which is beneficial to their application in the field of energy storage.
Figure 3. Lithium titanate anode material
- Li Hong, Li Jingze, Shi Lihong, et al. (2000) "Research on Lithium-ion Battery Nanomaterials " Electrochemistry, 6 (2): 131-145.
- Chen Liquan.(2002) "Research progress of cathode materials for lithium-ion batteries". Batteries, 32 (s1): 32-35.