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Unlike the lithium battery industry which has entered a cooling period, solid-state battery has continued to gain popularity this year. Data released by industry consulting firm Gaogong Lithium Battery shows that from January to July, the new capacity of solid-state batteries has exceeded 142GWh, involving a total investment of more than 64.4 billion yuan.

Thanks to their excellent performance, solid-state batteries have become the focus of major battery companies and the capital market. Industry insiders believe that as more and more companies compete in the solid-state battery track, it will promote the advancement of solid-state battery technology and process optimization, thereby accelerating its commercial application process.

On July 18, Sichuan's first solid-state battery innovation industrial park project was launched in Yibin City, with a total investment of 9.5 billion yuan. The first phase of the project currently underway mainly builds a 4GWh high-safety battery production line and a 30MWh all-solid-state battery pilot line.

In fact, many domestic battery manufacturers including CATL, Xinwangda, Guoxuan High-tech, Qingtao Energy, Sinovation, Honeycomb Energy, EVE Energy, and BYD Battery have announced their respective plans for solid-state battery products.

CATL recently stated that the company continues to increase investment in all-solid-state batteries and is expected to achieve small-scale production in 2027. On June 13, Xinwanda stated that the solid-state battery company has begun research and development since 2015, planning the first-generation 400Wh/kg and second-generation 500Wh/kg all-solid-state batteries. Among them, the latest ampere-hour samples of the first-generation all-solid-state batteries can achieve more than 1,000 stable cycles; the second-generation laboratory samples have reached the 500Wh/kg energy density target. In May, Guoxuan High-tech released the Jinshi battery using all-solid-state battery technology, with a cell energy density of 350Wh/kg, which is more than 40% higher than traditional liquid ternary lithium batteries.

There is no shortage of cross-border players in the field of solid-state batteries. Foxconn recently announced that it will focus on the solid-state battery industry in the Zhengzhou Airport Economic Comprehensive Experimental Zone to build solid-state electrolyte, semi-solid and all-solid-state battery cell R&D and production and manufacturing projects.

In addition, Japanese and Korean battery manufacturers such as LG Energy Solution and Samsung SDI have been in the solid-state battery field earlier and have continued to make efforts. In March this year, Samsung SDI first announced its high-performance solid-state battery mass production plan, which is planned to be mass-produced in 2027. It will use proprietary solid-state electrolytes and cathode-free technology, with an energy density of 900Wh/L. LG Energy Solution plans to launch polymer solid-state batteries and sulfide solid-state batteries in 2028, and higher-performance sulfide solid-state batteries in 2030.

Overall, compared with liquid batteries, solid-state batteries have many advantages such as high safety and high energy density. They meet the development needs of the next generation of battery technology and have therefore become the focus of research and development in various countries.

However, although solid-state batteries are becoming increasingly popular, the mass production schedules of battery companies and car companies for solid-state batteries are generally concentrated around 2027. In the view of industry insiders, the reason why solid-state batteries cannot be mass-produced in the short term is due to technical limitations in many aspects such as material interface and process.

Electrolyte is the core of solid-state batteries. Currently, the three mainstream solid-state battery electrolyte systems are oxides, sulfides and polymers, each with its own advantages and disadvantages in terms of conductivity and stability. It is understood that Samsung SDI, CATL and others prefer sulfide electrolyte systems, while some domestic companies such as Weilan New Energy choose the polymer + oxide composite route.

Overall, compared with the current mainstream liquid batteries, solid-state batteries use solid electrolytes, which leads to low ionic conductivity, slower battery charging and discharging speeds and faster capacity decay. In addition, compared with solid-liquid contact, the solid-solid interface contact and stability are worse.

"The interface stability between the electrolyte and the active material needs to be improved. In addition, sulfide electrolytes, for example, are highly sensitive to gases and are also more expensive. Polymer systems are easy to process and have good mechanical properties, but their conductivity is relatively poor." A practitioner told a reporter from China Energy News.

According to the proportion of liquid electrolyte in the battery cell, solid-state batteries can be divided into three categories: semi-solid, quasi-solid and all-solid. Among them, semi-solid and quasi-solid batteries contain a small amount of electrolyte inside, which is regarded as a transition route from liquid batteries to all-solid batteries. At present, most companies in my country regard semi-solid batteries as the first step in the research and development of solid-state batteries. "Semi-solid batteries contain a small amount of electrolyte, which is basically between existing liquid batteries and all-solid-state batteries. Its advantage is that it solves the problem of large interface impedance of all-solid-state batteries, and the price is relatively low, and it is easier to mass produce and apply." Industry insiders pointed out.

At present, the solid-state battery market has broad prospects and has become a battleground for all countries. It is worth noting that Japan, Europe and the United States are currently increasing their research and development efforts in all-solid-state batteries, intending to change the current situation where they lag behind China in liquid lithium batteries.

"At present, solid-state batteries have not yet been commercialized on a large scale, and the current mainstream liquid lithium batteries are also developing. There is no definite mainstream technical route for solid-state batteries in China and abroad. Chinese companies must first break through the technical bottleneck in developing solid-state batteries." The above-mentioned practitioners suggested,Chinese enterprises should further strengthen the collaborative cooperation between industry, academia and research, strengthen the research and development of new materials and new technologies, and first break through the technical bottlenecks to achieve further breakthroughs in technology level, industrial chain layout, application scenarios, cost reduction and other aspects.At the same time, we must strengthen basic subject research and patent layout.

At the same time, high costs are also a major bottleneck restricting the large-scale industrialization of solid-state batteries. A research report by CITIC Securities pointed out that the total costs of oxide semi-solid batteries and sulfide semi-solid batteries are currently about 0.76 yuan/Wh and 0.86 yuan/Wh, respectively, which are significantly higher than liquid lithium-ion batteries. In the future, it is necessary to achieve continuous cost reduction through R&D investment and scale effects.

It is worth mentioning that in response to the high cost of solid-state batteries, the University of Science and Technology of China recently developed a new sulfide solid electrolyte for all-solid-state batteries. The cost of its raw materials is only US$14.42 per kilogram, which is less than 8% of the raw material cost of other sulfide solid electrolytes.

CICC's research report pointed out that if solid-state batteries can give full play to and enhance their safety advantages, strive to occupy the advantage of energy density, and further optimize the rate, cycle life and processability, they can consolidate their core potential customers in advantageous scenarios; if there are breakthroughs in performance and cost, then their market space will expand and become a key technical route for lithium batteries. By 2025, the global market for various types of solid-state batteries may reach a scale of 100 billion yuan.