At present, the research of high-energy density lithium-ion batteries has shifted from the initial stage to substantive development. At present, many teams are also committed to the research of solid electrolytes, mainly to solve the safety hazards caused by the flammability of liquid electrolytes.

　　Battery technology plays an important role in the development of sustainable clean energy in society. Compared with traditional nickel-hydrogen batteries and lead-acid batteries, lithium-ion batteries have the characteristics of high energy density, no memory effect, and low environmental pollution, and are widely used in the field of energy storage and conversion. Today, lithium-ion batteries have been used as power batteries in electric vehicles such as Tesla and BYD, and have a huge market share. The global lithium-ion battery market is expected to reach 450 billion yuan in 2020.

　　Lithium-ion battery was first successfully developed by Sony Corporation of Japan in 1990. The positive electrode material of the traditional lithium ion battery is lithium cobalt oxide (LiCoO2), the negative electrode material is graphite (C), and the rechargeable battery uses esters as the electrolyte. The electrode reaction formula of the battery is as follows:

　　However, the actual specific capacity of the lithium cobalt oxide material is only about 150mAh/g, and the lower capacity limits the improvement of the energy density of the single lithium ion battery, which is only about 150Wh/kg. The use of lower energy density lithium-ion batteries as the power battery of the car makes the electric car unable to have the expected mileage. For example, Tesla's newest electric car ModelX, its battery pack is composed of more than 7,000 18650 lithium-ion batteries, weighing about one ton. The heavy battery pack increases the weight of the car and reduces the mileage of the car. The mileage after a full charge is about 400 kilometers. Therefore, the development of high-energy-density lithium-ion batteries is particularly important.

　　At present, the research of high energy density lithium-ion batteries has shifted from the initial stage to substantive development. The research field is mainly concentrated on the positive electrode material and negative electrode material of the battery. In the positive electrode, the main research is lithium-rich cathode materials, high nickel cathode materials and sulfur cathode materials. The research on the negative electrode mainly focuses on the tin negative electrode, silicon negative electrode and lithium metal negative electrode. At present, many teams are also committed to the research of solid electrolytes, mainly to solve the safety hazards caused by the flammability of liquid electrolytes. In addition, in the research of lithium metal anode, the introduction and use of solid electrolyte can inhibit the growth of lithium dendrites. This article combines some of the world's top lithium battery research teams to give a brief introduction, and explain the hot research directions of the industry.