The Critical Juncture for Solid-State Batteries?
As one of the hottest investment areas in battery technology, solid-state batteries have distinct advantages over traditional liquid batteries in terms of energy density and safety. They are widely regarded as the most promising next-generation battery technology. With the scale production of solid-state batteries, does this mean that the industry has reached a commercial breakthrough?
Recently, China Science and Technology Fusion Energy has successfully scaled up production and rolled out its 628Ah and 314Ah solid-state batteries. As one of the most popular investment fields in batteries, solid-state batteries have notable advantages over traditional liquid batteries in terms of energy density and safety, garnering widespread attention within the industry. With the scale production of solid-state batteries, does this signal a commercial milestone for the industry?
Acceleration of Semi-Solid Battery Industrialization
Currently, the mainstream lithium batteries in the market use liquid electrolytes as transmission carriers. Under abnormal conditions such as overcharging or internal short circuits, the liquid electrolyte can easily heat up, decompose, and generate gas, potentially leading to battery fires or explosions. Replacing liquid electrolytes with solid electrolytes can fundamentally solve the safety issues of lithium batteries, while also meeting the demand for higher energy density and better performance.
It is understood that the solid-state batteries being discussed in the industry typically refer to semi-solid batteries, quasi-solid batteries, or solid-liquid hybrid batteries with a reduced electrolyte content of 5%-15%. These retain some liquid electrolyte, making them feasible for mass production in terms of material design, manufacturing process, equipment production, and cost.
"Leveraging the robust manufacturing foundation of the new energy industry chain, Chinese battery companies have made significant breakthroughs in the research and development of solid-state battery technology and industrial chain layout. With the mass production of semi-solid batteries by Chinese companies such as WeLion New Energy, Qingtao Energy, and Ganfeng Lithium, semi-solid batteries have truly achieved industrialization in an economic sense," said Yu Qingjiao, Secretary-General of the New Battery Technology Innovation Alliance of Zhongguancun, at the recent 2024 Solid-State Battery Industry Ecosystem Summit. He pointed out that the commercial application of solid-state batteries is approaching, and whoever captures the high ground of the industry first will gain the initiative in development.
Challenges in Fully Solid-State Battery Commercialization
Despite the mass production and application of semi-solid batteries, the commercialization of fully solid-state batteries still faces a series of challenges in terms of technology and cost.
Replacing liquid electrolytes with solid electrolytes involves a core technical issue of material selection. The industry has explored three main solid-state battery systems: polymer, sulfide, and oxide. Polymer solid electrolytes are easy to process, compatible with both dry and wet manufacturing processes, and have the lowest mass production difficulty, but have low conductivity. European companies mostly focus on this technical route. Sulfides have the best performance but are sensitive to moisture in the air and most polar solvents, and the manufacturing of cells requires pressure from isostatic pressing equipment, leading to high costs. Chinese companies like CATL, BYD, and EVE Energy favor this technical route. Some startups opt for the oxide route.
"Fully solid-state batteries represent a comprehensive innovation upgrade in materials, cell manufacturing processes, and manufacturing equipment. The industrial chain will undergo revolutionary changes," said Miao Lixiao, General Manager of Frontier Technology R&D at SVolt Energy. He noted that solid-state batteries face challenges in system design and recycling. For example, during manufacturing, liquid batteries use separators to wrap around the electrodes to prevent misalignment that could cause short circuits, and they do not require ultra-high pressure densification. However, solid-state batteries lack separators, and the stacked layers are densified under ultra-high pressure, making the edges of the electrodes prone to breaking and misalignment, making insulation on the cell sides challenging. "Solid-state batteries are like hamburgers, layered with ingredients that can spill out from the edges under pressure, leading to short circuits, while liquid batteries are like rolled pancakes, wrapped to avoid short circuits."
Currently, the cost of solid-state batteries is higher than that of liquid batteries. Miao Lixiao cited that "the cost of sulfide solid electrolyte materials is extremely high, reaching 20,000 yuan per kilogram, with the potential to drop to 5,000 yuan per kilogram in the future. However, solid electrolytes account for over 20% of the cell mass, and such prices are likely unacceptable in the market."
Pitao, Chairman of Hunan Zhongke Xingcheng Graphite Co., Ltd., pointed out, "Every company has its own technical characteristics. Due to the uncertainty of technical directions, the upstream industrial chain is in a wait-and-see state. Solid-state batteries need a relatively determined direction for upstream and downstream to configure products accordingly, avoiding greater sunk costs in capital investment."
Achieving 1+1>2 Through Composite Material Design
Due to unclear technical routes and cost reduction spaces, companies in the industry are choosing to gradually transition from semi-solid to fully solid-state.
"There are differences in the fully solid-state battery route, and differentiated competition will promote the expansion of solid-state battery applications," said Xu Hangyu, Director of Scientific Research and Development at WeLion New Energy. He believes that currently, a single solid electrolyte material cannot meet the needs of fully solid-state batteries. Combining liquid and solid electrolytes is one solution, compensating for the shortcomings of single electrolyte materials while being compatible with most traditional liquid lithium battery processes and equipment, reducing costs. Combining the advantages of oxide and polymer solid electrolytes, WeLion New Energy has industrialized mixed solid-liquid batteries, with products used in small power, new energy vehicles, and energy storage fields.
"Each type of material has its own advantages and disadvantages. Through composite material design, 1+1>2 can be achieved," said an industry insider, who also believes that composite solid-state batteries are an effective way to achieve large-scale production. "Solid-state batteries cannot be made into a work of art, with products being very expensive, several times or even ten times more than liquid batteries, which would never be feasible for vehicle applications."
Su Min, Director of the Cell Materials R&D Department at Wanxiang 123 Co., Ltd., believes that whether semi-solid or fully solid-state, there is an optimal energy density. There is no single best technology solution; all are technical means to address safety risks under high specific energy needs. Overcoming the technical and industrialization issues of fully solid-state batteries requires the collective efforts of the entire industry.
