Advantages and bottlenecks of solid state batteries

Traditional lithium-ion batteries are made of a positive electrode, a diaphragm, a negative electrode, and an electrolyte. Solid-state lithium-ion batteries, as the name suggests, use solid electrolytes instead of membranes and electrolytes. Compared with traditional lithium batteries, solid-state batteries have several advantages, such as high energy density, high safety and flexibility of thin film, but solid-state batteries are still not commercially available.

Three bottlenecks limit the commercial use of solid state batteries: first, the low conductivity of solid electrolyte ions leads to the overall low rate performance and large internal resistance, so it cannot meet the requirements of fast charging temporarily. Secondly, the mechanical properties of solid electrolyte are poor, and the interface contact between solid electrode and solid electrolyte is poor, which will affect the cycle life and rate performance of solid state lithium battery. In addition, high cost is also the existing drawback of solid state battery. At present, solid electrolytes are mainly divided into polymer, oxide and sulfide three kinds, but at present, their performance is difficult to reach the level of liquid electrolyte, and the material cost is expensive, the processing difficulty is extremely high, need continuous investment.

Solid state battery development trend

In the face of the importance of solid-state battery to the development of new energy vehicles, various fields are also increasing investment, in order to break the bottleneck of solid-state battery as soon as possible.

Japan: The New Energy Industry Technology Development Agency of Japan (NEDO) started a project to develop all-solid-state batteries in 2018 and plans to invest 10 billion yen over the next five years from 2018-2022. Automakers such as Toyota, Nissan, and Honda Technology Research Institute are developing the battery under an all-Japan system in collaboration with Panasonic and Jesz Yuasa.

South Korea: In November 2018, LG Chem, Samsung SDI and SK Innovation announced that they will jointly establish a 100 billion won fund for technology research and development in solid-state, lithium-metal and lithium-sulfur batteries.

Europe: The German government plans to spend more than 1 billion euros to support a battery research and development alliance involving Valtameco Battery, chemical giant BASF and Ford Germany, Ford's German subsidiary, which will focus on solid-state batteries.

Automotive giants are also eyeing solid-state batteries. Volkswagen has become the largest shareholder in solid-state battery startup QuantumScape with a $100 million investment. QuantumScape has more than 200 solid-state battery technology patents and patent filings and aims to establish a solid state battery production line by 2025. BMW partnered with solid-state battery company Solid Power in 2017 to develop all-solid-state batteries.

United States: There are a large number of university-derived startups, such as QuantumScape, SEEO, Solid Power, Solid Energy Systems, Ionic Materials, etc. These startups are advanced in solid-state battery technology, Ensuring that the United States is placed in the second tier of global solid state battery research.

China: In China, companies including Ningde Times, Ganfeng Lithium, Beijing Weilan, Guoxuan Gaocco, Jiawei Company, Penghui Energy, Huineng Technology, BYD, etc., have all carried out solid state lithium battery related layout.

Recently, battery enterprises announced the latest progress. According to the company, the first generation of solid-state power batteries will be produced on a trial basis in 2017-2018, and 1GWh of first-generation solid-state power batteries will be achieved in 2020. Beijing Weilan New energy also said that in 2021 the company's semi-solid vehicle power battery will be marketed.

Capacity will become an important weight to reduce costs

According to the data, the global demand for solid state lithium battery is expected to reach 1.7 GWh in 2020, 44.2 GWh in 2025 and 494.9 GWh in 2030, and the global market space is expected to reach more than 150 billion yuan in 2030. According to Huaneng's previous calculation, when the production capacity of solid-state battery reaches 20GWh, its cell cost is still 1.1 times that of liquid lithium battery, while the battery pack cost can achieve 98% of liquid battery. Therefore, for the cost issue, the industry generally believes that most of the production costs of solid-state batteries are production process costs, and the expansion of production scale in the future will become an important weight to reduce the cost of batteries.

Gradually reduce the use of liquid, from semi-solid state battery to quasi-solid state battery, and finally towards the liquid free solid-state battery, will be the mature development trend of solid-state battery. As an important propeller for the development of new energy vehicles, liquid lithium batteries, solid state batteries, fuel cells and even aluminum-air batteries all have their own advantages and disadvantages, but it is the trend of lithium batteries to become solid state. But in the long development path of new energy vehicles in the future, solid-state batteries may be another beautiful stop.