Lithium batteries are new high-energy batteries developed successfully in the 20th century. They can be understood as batteries containing lithium elements (including lithium metal, lithium alloy, lithium ion, lithium polymer). They can be divided into lithium metal batteries (rarely produced and used) and lithium ion batteries (widely used nowadays). Because of its advantages of high specific energy, high battery voltage, wide operating temperature range and long storage life, it has been widely used in military and civilian small electrical appliances, such as mobile phones, portable computers, cameras, cameras and so on, partly replacing traditional batteries.

Origin and Development of Lithium Ion Batteries

In the 1970s, M.S. Whittingham of Exxon made the first lithium battery by using titanium sulfide as cathode material and lithium metal as cathode material.

In 1980, J. Goodenough found that lithium cobalt can be used as cathode material for lithium ion batteries.

In 1982, R. R. Agarwal and J. R. Selman of the Illinois Institution of Technology found that lithium ions had the characteristics of graphite intercalation, and the process was fast and reversible. At the same time, the potential safety hazards of lithium batteries made of lithium metal have attracted much attention, so people try to make rechargeable batteries by using the characteristics of lithium ion embedded in graphite. The first available lithium ion graphite electrode was successfully fabricated by Bell Laboratory.

In 1983, M. Thackeray, J. Goodenough and others found that manganese spinel is an excellent cathode material with low cost, stability and excellent conductivity and lithium conductivity. Its decomposition temperature is high, and its oxidation is much lower than that of lithium cobalt oxide. Even if there is short circuit and overcharge, it can avoid the danger of combustion and explosion.

In 1989, A. Manthiram and J. Goodenough found that positive electrodes using polymeric anions produced higher voltages.

Sony released its first commercial lithium-ion battery in 1991. Subsequently, lithium-ion batteries revolutionized the face of consumer electronics.

In 1996, Padhi and Goodenough found that olivine-structured phosphates, such as LiFePO4, have more advantages than traditional cathode materials, and have become the mainstream cathode materials.

Lithium-ion batteries (Li-ion Batteries) are the development of lithium batteries. So before introducing Li-ion, we first introduce lithium batteries. Button batteries, for example, belong to lithium batteries. The cathode material of lithium battery is manganese dioxide or thionyl chloride, and the cathode is lithium. When the battery is assembled, the battery will have voltage and need not be charged. This kind of battery can also be charged, but its cycle performance is not good. In the process of charging and discharging cycle, lithium dendrite is easy to form, resulting in short circuit inside the battery, so this kind of battery is generally prohibited from charging.

Later, Sony Corporation of Japan invented lithium-ion batteries with carbon as the negative electrode and lithium-containing compounds as the positive electrode. In the process of charging and discharging, there is no lithium metal, only lithium ion, which is lithium-ion batteries.

In the early 1990s, Sony Energy Development Company of Japan and Moli Energy Company of Canada developed new lithium-ion batteries, which not only had good performance, but also had no pollution to the environment. With the rapid development of information technology, hand-held machinery and electric vehicles, the demand for high-efficiency power supply has increased dramatically. Lithium batteries have become one of the most rapidly developed areas.

Structure and Principle of Lithium Ion Battery

The main components of lithium ion batteries are as follows:

(1) The cathode-active material mainly refers to lithium cobalt oxide, lithium manganate, lithium iron phosphate, lithium nickel oxide, lithium nickel cobalt manganate and so on. The conductive collector usually uses aluminum foil with thickness of 10-20 microns.

(2) Diaphragm, a special plastic film, can let lithium ions pass through, but it is an electronic insulator. At present, there are mainly two kinds of PE and P P and their combination. There is also a kind of inorganic solid diaphragm, such as alumina diaphragm coating is an inorganic solid diaphragm.

(3) Anode-active material mainly refers to graphite, lithium titanate, or carbon materials with similar graphite structure. The conductive collector usually uses copper foil with thickness of 7-15 microns.

(4) electrolyte — generally organic system, such as carbonate solvent dissolved with six fluorolithium phosphate, and some polymer batteries use gel electrolyte.

(5) Battery shell – mainly divided into hard shell (steel shell, aluminum shell, nickel-plated iron shell) and soft package (aluminum-plastic film).

When the battery is charged, lithium ions are detached from the positive electrode, embedded in the negative electrode, and vice versa when the battery is discharged. This requires an electrode to be in the lithium intercalation state before assembly. Generally, the transition metal oxides with a potential greater than 3V and a stable lithium intercalation in air, such as LiCoO 2, LiNiO 2 and LiMnO 4, are chosen as positive electrodes.

As a negative electrode material, the selective potential is as close as possible to the lithium potential of intercalable lithium compounds, such as natural graphite, synthetic graphite, carbon fibers, mesophase spheroidal carbon and metal oxides, including SnO, SnO 2, SnBxPyOz (x = 0.4-0.6, y = 0.6-0.4, z = 2 + 3x + 5y)/2, etc.

LiPF6 ethylene carbonate (EC), propylene carbonate (PC) and low viscosity diethyl carbonate (DEC) were used as mixed solvents in the electrolyte system.

Polyolefin micro-porous membranes such as PE, PP or their composite membranes, especially PP/PE/PP three-layer membranes, not only have low melting point, but also have high puncture resistance and play a thermal insurance role.

The shell is made of steel or aluminium, and the cover body has the function of explosion-proof and power-off.

Basic working principle

When the battery is charged, the lithium-containing compounds in the positive electrode are removed, and the lithium ions move to the negative electrode through the electrolyte. Negative carbon