Lithium ion battery starts to rush all the way, approaching power battery

In 1800, Alessandro Volta, an Italian physicist, invented the Volta stack, the first battery in human history. The first battery was made of zinc (anode) and copper (cathode) sheets and paper soaked in salt water (electrolyte), demonstrating the artificial possibility of electricity.

Since then, as a device that can provide continuous and stable current, batteries have experienced more than 200 years of development and continue to meet people's demand for flexible electricity use.

In recent years, with the huge demand for renewable energy and increasing concern about environmental pollution, secondary batteries (or batteries) that can convert other forms of energy into electrical energy and store it in the form of chemical energy continue to bring changes to the energy system.

The development of lithium battery shows the progress of society from another aspect. In fact, the rapid development of mobile phones, computers, cameras and electric vehicles is based on the maturity of lithium battery technology.

Chen Gen. The birth and anxiety of lithium battery are approaching

The birth of lithium battery

The battery has positive and negative poles. The positive pole, also known as the cathode, is usually made of more stable materials, while the negative pole, also known as the anode, is usually made of "highly active" metal materials. The positive and negative poles are separated by electrolyte and stored in the form of chemical energy.

The chemical reaction between the two poles produces ions and electrons. These ions and electrons move in the battery, forcing electrons to move outward, forming a cycle and generating electricity.

In the 1970s, the oil crisis in the United States, coupled with new power demand in military, aviation, medicine and other fields, stimulated the search for rechargeable batteries to store renewable clean energy.

Of all metals, lithium has a very low specific gravity and electrode potential. In other words, lithium battery system can achieve the maximum energy density in theory, so lithium is the natural choice of battery designers.

However, lithium is highly reactive and can burn and explode when exposed to water or air. Therefore, taming lithium has become the key to battery development. In addition, lithium can easily react with water at room temperature. If metal lithium is to be used in battery systems, it is essential to introduce non-aqueous electrolytes.

In 1958, Harris proposed to use organic electrolyte as the electrolyte of metal battery. In 1962, Lockheed Mission and SpaceCo. Chilton Jr. of the U.S. military And Cook put forward the idea of "lithium non-aqueous electrolyte system".

Chilton and Cook designed a new type of battery, which uses lithium metal as cathode, Ag, Cu, Ni halides as cathode, and low melting point metal salt lic1-AlCl3 dissolved in propylene carbonate as electrolyte. Although the problem of the battery makes it stay in the concept rather than commercial feasibility, Chilton and Cook's work is the beginning of lithium battery research.

In 1970, Panasonic Electric Co. of Japan and the US military independently synthesized a new cathode material - carbon fluoride almost at the same time. The crystalline carbon fluoride with the molecular expression of (CFx) N (0.5 ≤ x ≤ 1) was successfully prepared by Panasonic Electric Co., Ltd. and used as the anode of lithium battery. The invention of lithium fluoride battery is an important step in the history of lithium battery development. This is the first time to introduce "embedded compound" into the design of lithium battery.

However, in order to realize the reversible charge and discharge of lithium battery, the key is the reversibility of chemical reaction. At that time, most non rechargeable batteries used lithium anodes and organic electrolytes. In order to realize rechargeable batteries, scientists began to study the reversible insertion of lithium ions into the positive electrode of layered transition metal sulfide.

Stanley Whittingham of ExxonMobil found that the intercalation chemical reaction can be measured by using layered TiS2 as the cathode material, and the discharge product is LiTiS2.

In 1976, the battery developed by Whittingham achieved good initial efficiency. However, after repeated charging and discharging for several times, lithium dendrites formed in the battery. The dendrites grew from the negative pole to the positive pole, forming a short circuit, which caused the danger of igniting the electrolyte and ultimately failed.

In 1989, due to the fire accident of lithium/molybdenum secondary batteries, most companies except a few withdrew from the development of lithium metal secondary batteries. The development of lithium metal secondary batteries was basically stopped because the safety problem could not be solved.

Due to the poor effect of various modifications, the research on lithium metal secondary battery has been stagnant. Finally, the researchers chose a radical solution: a rocking chair battery with embedded compounds as the positive and negative poles of lithium metal secondary batteries.

In the 1980s, Goodnow studied the structure of layered lithium cobalate and lithium nickel oxide cathode materials at Oxford University, England. Finally, researchers realized that more than half of lithium can be removed from the cathode material reversibly. This result finally led to the birth of The.

In 1991, SONY Company launched the first commercial lithium battery (anode graphite, cathode lithium compound, electrode liquid lithium salt dissolved in organic solvent). Due to the characteristics of high energy density and different formulations that can adapt to different use environments, lithium batteries have been commercialized and widely used in the market