Solid-state batteries: the next-generation battery route

Solid-state batteries: the next-generation battery route

On May 14, according to "The Korea Times" and other media reports, Samsung plans to cooperate with Hyundai to develop electric vehicles and provide power batteries and other connected car parts for Hyundai electric vehicles. The media predicts that Samsung and Hyundai will soon sign a non-binding memorandum of understanding on battery supply. It is reported that Samsung introduced its latest solid-state battery to Hyundai.

According to Samsung, when its prototype battery is fully charged, it can allow an electric car to drive more than 800 kilometers at a time, with a battery cycle life of more than 1,000 times. Its volume is 50% smaller than a lithium-ion battery of the same capacity. For this reason, solid-state batteries are considered to be the most suitable power batteries for electric vehicles in the next ten years.

In early March 2020, Samsung Institute for Advanced Study (SAIT) and Samsung Research Center of Japan (SRJ) published "High-energy long-cycling all-solid-state lithium metal batteries enabled by silver" in "Nature Energy" magazine. -Carbon composite anodes" introduced their latest development in the field of solid-state batteries.

This battery uses a solid electrolyte, which is not flammable at high temperatures and can also inhibit the growth of lithium dendrites to avoid puncture short circuits. In addition, it uses a silver-carbon (Ag-C) composite layer as the anode, which can increase the energy density to 900Wh/L, has a long cycle life of more than 1000 cycles, and a very high coulombic efficiency (charge and discharge efficiency) of 99.8%. It can drive the battery after a single payment. The car traveled 800 kilometers.

However, the SAIT and SRJ that published the paper are scientific research institutions rather than Samsung SDI, which focuses on technology. The article only clarifies the new battery's principle, structure, and performance. It is preliminary judged that the battery is still in the laboratory stage and will be difficult to mass-produce in a short period.

The difference between solid-state batteries and traditional liquid lithium-ion batteries is that solid electrolytes are used instead of electrolytes and separators. It is not necessary to use lithium-intercalated graphite anodes. Instead, metal lithium is used as the anode, which reduces the number of anode materials. Power batteries with higher body energy density (>350Wh/kg) and longer life (>5000 cycles), as well as special functions (such as flexibility) and other requirements.

The new system batteries include solid-state batteries, lithium flow batteries, and metal-air batteries. The three solid-state batteries have their advantages. Polymers electrolytes are organic electrolytes, and oxides and sulfides are inorganic ceramic electrolytes.

Looking at the global solid-state battery companies, there are start-ups, and there are also international manufacturers. The companies are alone in the electrolyte system with different beliefs, and there is no trend of technology flow or integration. At present, some technical routes are close to the conditions of industrialization, and the road to the automation of solid-state batteries has been in progress.

European and American companies prefer polymer and oxide systems. The French company Bolloré took the lead in commercializing polymer-based solid-state batteries. In December 2011, its electric vehicles powered by 30kwh solid-state polymer batteries + electric double-layer capacitors entered the shared car market, which was the first time in the world. Commercial solid-state batteries for EVs.

Sakti3, a thin-film oxide solid-state battery manufacturer, was acquired by British home appliance giant Dyson in 2015. It is subject to the cost of thin-film preparation and the difficulty of large-scale production, and there has been no mass production product for a long time.

Maxwell's plan for solid-state batteries is to enter the small battery market first, mass-produce them in 2020, and use them in the field of energy storage in 2022. For the sake of rapid commercial application, Maxwell may first consider trying semi-solid batteries in the short term. Still, semi-solid batteries are more expensive and are primarily used in particular demand fields, making large-scale applications difficult.

Non-thin-film oxide products have excellent overall performance and are currently popular in development. Both Taiwan Huineng and Jiangsu Qingdao are well-known players on this track.

Japanese and Korean companies are more committed to solving the industrialization problems of the sulfide system. Representative companies such as Toyota and Samsung have accelerated their deployment. Sulfide solid-state batteries (lithium-sulfur batteries) have colossal development potential due to their high energy density and low cost. Among them, Toyota's technology is the most advanced. It released ampere-level Demo batteries and electrochemical performance. At the same time, they also used LGPS with higher room temperature conductivity as the electrolyte to prepare a larger battery pack.

Japan has launched a nationwide research and development program. The most promising alliance is Toyota and Panasonic (Toyota has nearly 300 engineers involved in developing solid-state batteries). It said it would commercialize solid-state batteries within five years.

The commercialization plan of all-solid-state batteries developed by Toyota and NEDO begins with developing all-solid-state batteries (first-generation batteries) using existing LIB upbeat and harmful materials. After that, It will use new positive and negative materials to increase the energy density (next-generation batteries). Toyota is expected to produce prototypes of solid-state electric vehicles in 2022, and It will use solid-state batteries in some models in 2025. In 2030, the energy density can reach 500Wh/kg to achieve mass production applications.

From the perspective of patents, among the top 20 patent applicants for solid-state lithium batteries, Japanese companies accounted for 11. Toyota applied for the most, reaching 1,709, 2.2 times that of the second Panasonic. The top 10 companies are all Japanese and South Korean, including 8 in Japan and 2 in South Korea.

From the perspective of patentees' global patent layout, Japan, the United States, China, South Korea, and Europe are the key countries or regions. In addition to local applications, Toyota has the most significant number of applications in the United States and China, accounting for 14.7% and 12.9% of the total patent applications, respectively.

The industrialization of solid-state batteries in my country is also under constant exploration. According to China's technical route plan, in 2020, It will gradually realize solid electrolyte, high specific energy cathode material synthesis, and three-dimensional framework structure lithium alloy construction technology. It will recognize 300Wh/kg small-capacity single battery sample manufacturing. In 2025, solid-state battery interface control technology will realize 400Wh/kg large-capacity single battery sample and group technology. It is expected that solid-state batteries and lithium-sulfur batteries can be mass-produced and promoted in 2030.

The next-generation batteries in the IPO fundraising project of CATL include solid-state batteries. According to NE Times reports, CATL expects to achieve mass production of solid-state batteries by at least 2025.

On the whole, the polymer system technology is the most mature, and the first EV-level product is born. Its conceptual and forward-looking nature has triggered the acceleration of investment in research and development by latecomers, but the upper limit of performance restricts growth, and compounding with inorganic solid electrolytes will be a possible solution in the future; oxidation; In the material system, the development of thin-film types is focused on capacity expansion and large-scale production, and the overall performance of non-film types is better, which is the focus of current research and development; sulfide system is the most promising solid-state battery system in the field of electric vehicles, But in a polarized situation with massive room for growth and immature technology, solving security issues and interface issues is the focus of the future.

The challenges faced by solid-state batteries mainly include:

• Reducing costs.
• Improving the safety of solid electrolytes.
• Maintaining contact between electrodes and electrolytes during charging and discharging.

Lithium-sulfur batteries, lithium-air, and other systems need to replace the entire battery structure frame, and there are more and more significant problems. The positive and negative electrodes of solid-state batteries can continue to use the current system, and the difficulty of realization is relatively tiny. As the next-generation battery technology, solid-state batteries have higher safety and energy density and will become the only way in the post-lithium era.