Solid state battery-the next high performance battery

As the use of electric vehicles increases, their safety becomes a core element. Solid state batteries are an important direction and technology to address safety and improve energy density, and many companies are currently focusing on developing solid state batteries.

Solid state battery using solid electrolyte instead of liquid electrolyte can significantly improve the energy density and safety of lithium batteries, which is the long-term potential technology direction of the existing battery system.

In terms of application fields, solid state batteries are expected to be commercialized from the high-end application market first, and gradually expand to the power and consumer battery fields. Based on the excellent performance of solid state batteries, the industry has great potential for future development.

Solid state battery industry overview

Solid state battery classification

According to the classification of electrolyte, lithium batteries can be divided into four categories: liquid, semi solid, quasi solid and all solid, of which semi-solid, quasi-solid and all-solid are collectively known as solid state batteries.

Solid state lithium ion batteries are technically difficult. At present, mainstream manufacturers involved in the field of solid-state batteries are in the form of semi-solid and quasi-solid to improve the energy density, while stockpiling the technology of solid state lithium ion battery.

The technological development of solid state batteries adopts a gradual conversion strategy, with the liquid electrolyte content gradually decreasing and all-solid state batteries being the final form.

However, at present, solid state batteries are still in the initial stage from laboratory to industrialization, or from pilot to industrialization, and it takes a long time before mass production.

On the one hand, there are still many technical difficulties in the production of all-solid state batteries.

• The ionic conductivity of the solid electrolyte is much lower than that of the liquid electrolyte, which makes the internal resistance of the battery increase significantly.
• The cyclability of the battery  and the performance of the multiplier become worse.

On the other hand, the high cost is also a factor that restricts the commercialization of all-solid state batteries.

The current industry chain of liquid lithium batteries is very mature and can produce lithium batteries with better performance at low cost, while the industry chain of all-solid state batteries is not perfect.

Semi solid state batteries

The semi solid state path has less iteration for the existing liquid lithium-ion battery system and is considered a transition path to the all solid state.

The semi solid route will still use diaphragm and liquid electrolyte. By reducing the content of liquid electrolyte inside the battery, it can improve the specific energy and safety of the battery to a certain extent.

The preparation method mainly follows the traditional lithium-ion battery process and equipment technology. And its development technology route.

Solid state battery technology

Solid state batteries usually use a soft pack and stacked chip packaging process, with large variations in the middle and end process, without the need to inject liquefaction into the process.

The semi-solid state batteries supply chain as a transition stage has a high degree of overlap with the existing supply chain, driving innovation in key material systems such as new additives, composite coated diaphragms, gel-state electrolytes, and high-performance positive and negative electrodes.

The diaphragm adds value through the composite solid electrolyte coating, electrolyte additives for in-situ solid state synthesis of composite solid electrolytes, and the solid electrolyte film formation process becomes critical.

Classified in terms of changes in material systems, the line of technological progress in solid state batteries can be divided into three stages.

• The traditional liquid electrolyte is replaced by solid electrolyte, and the anode and cathode materials remain unchanged.

At this stage, by reducing the amount of electrolyte, theoretically there is a certain improvement in safety.

However, since there is no essential change in the positive and negative electrode material system, it is impossible to reduce the increase in the cost of solid state batteries by improving energy density.

At present, most manufacturers’ mass production planning is based on this stage, which is mainly used to overcome the difficulty of solid state electrolyte technology and mass production.

• The anode is replaced by lithium metal, and the cathode material remains unchanged.

The cost of solid state batteries based on lithium metal cathodes can significantly improve energy density and cost less than traditional liquid batteries, which is the key to reducing the cost of solid state batteries. But lithium metal cathodes still face many scientific and technical problems.

• Use lithium metal for the anode, and replace the cathode with a higher energy material.

On the basis of lithium metal cathode, the energy density can continue to be improved through the renewal of cathode materials. But there are more technical problems to be solved and the realization cycle is more distant.

Solid state battery industry

Three paths for the development of solid state lithium batteries are polymer, oxide and sulfide electrolytes.

The oxide system is currently the fastest-paced, followed by the sulfide system, and the high-energy polymer system is still in the laboratory research stage.

• In terms of cost, sulfide systems are the most cost-effective and likely to be the future commercial technology path.
• From the technical point of view, the mainstream technology is dominated by oxide and sulfide electrolytes, with oxide prevailing in stability and sulfide in conductivity.

Industry chain layout solid state battery enterprises

The research and development of solid state batteries is mainly concentrated in five countries and regions, China, Japan, Korea, the United States and Europe.

① The four leading solid state battery manufacturers in China (Welion, Qingtao, Ganfeng BATTERY, and ProLogium) are all based on solid-liquid hybrid technology based on oxide materials.

Ganfeng BATTERY takes the oxide thick film route, and both Farasis and Ganfeng BATTERY have built pilot production lines.

SVOLT’s semi solid state jelly battery is already in production.

Compared to the development of semi-solid state batteries, CATL favours the development of sulfide electrolytes, while focusing on improving performance through cell structure modification.

② Japan is currently the world’s technology leader due to its early planning and development of industrialization of solid-state batteries.

③ The three largest battery companies with leading technology in Korea have also chosen to jointly develop solid state batteries. Representative companies include LG Chem, Samsung, and others.

④ Major European and U.S. automakers are trying to acquire technology reserves by investing in startups such as Solid Power, Solid Energy Systems, Ionic Materials, and Quantum Scape.

Although BYD, Apple, and other companies began planning the layout of solid state battery R&D early, most companies did not start investing in solid state batteries until 2018.

Some Chinese companies have entered the pilot phase of solid state lithium-ion batteries (semi-solid state batteries), and mass production of solid state batteries may be achieved by 2025.

Ganfeng BATTERY, Welion, Qingtao and other startups are progressing faster. At present, the capacities built by Welion and Qingtao are semi solid state batteries, and all solid state is still in the laboratory R&D stage.

The semi-solid state battery adds materials such as solid electrolyte coatings and in-situ solidified lithium salts, and the incremental material supply chain and its suppliers such as lithium lanthanum zirconium oxide (LLZO), lithium titanium aluminum phosphate (LATP), sulfide solid electrolytes, and new lithium salts are expected to see opportunities.

Industry chain layout enterprises also include Goyion, SVOLT, AVIC Lithium, AVIC, CENAT, Farasis, etc.

Industry chain layout car enterprises

Car companies

Car companies are also accelerating the deployment of solid state battery, with emerging electric vehicle manufacturers moving at a faster pace.

At present, there are many players in the battery market, including car companies, battery companies, investment institutions, and research institutions, which play games in terms of capital, technology, and talent.

Mature application requirements for solid state batteries:

• The construction of a complete industrial chain supply chain.
• The cooperation of various industries to optimize and develop new cathode, cathode, electrolyte, pre-lithiation and other materials.
• To develop new process technologies to reduce production and manufacturing costs.
• Jointly build the industrial chain and supply chain construction.

From a global perspective, solid state batteries are still in the early stages of industrialization, and it still takes a long time to overcome the existing technical problems.