Solid-State Battery Takes Off: How to Achieve the Breakthrough from 0 to 1 in Mass Production?

From the range anxiety of electric vehicles to the pursuit of high energy density in consumer electronics, the development of solid-state batteries has attracted considerable attention.

Solid-state batteries fundamentally address the safety issues caused by electrolyte leakage and combustion in liquid batteries. Meanwhile, the high ionic conductivity and low resistance characteristics of solid electrolytes enable solid-state batteries to achieve higher energy density and faster charging speeds, providing the possibility for enhancing the endurance of electric vehicles and popularizing charging facilities.

The development of solid-state batteries is crucial for industrial upgrading and renewal, making it particularly important to deeply analyze the technical routes and key industrialization aspects of solid-state batteries.

I. Technological Upgrades: From Semi-Solid Oxides to Fully Solid Sulfides

The mainstream solid-state battery technology routes are divided into polymers, oxides, and sulfides based on electrolytes. Among them, polymer solid electrolytes are easy to synthesize and process and have been the first to achieve commercial applications, but their conductivity at room temperature is low, limiting the overall performance improvement. Oxide solid electrolytes are insensitive to water and oxygen, have moderate conductivity, good thermal stability, and a high electrochemical window, but they have poor processability and interface contact issues. Sulfide solid electrolytes have high conductivity but poor chemical stability and high manufacturing costs.

The development of solid-state battery technology from research to industrialization is undergoing two stages:

Stage 1: Introduce solid electrolytes while retaining a small amount of liquid electrolyte, with ternary materials and graphite/silicon anodes remaining as the cathode and anode, respectively, and technologies such as anode pre-lithiation are adopted to increase energy density.

Stage 2: Gradually and completely replace the liquid electrolyte with solid electrolytes, replace the graphite/silicon anode with lithium metal, and keep the ternary material as the cathode.

1.0 Era: Oxide Semi-Solid Takes the Lead

With the advancement of research, the industrial application advantages of oxides in solid-liquid hybrid batteries have become prominent. Especially in China, oxide solid electrolytes, supported by their moderate conductivity, good chemical stability, and low material prices, have become the mainstream choice for domestic solid-state battery research teams.

Domestic battery enterprises have entered the field of solid-state battery technology, and most of them have reserved solid-state battery technology. In terms of mass production, the oxide system has moderate preparation difficulty, and many new players and domestic enterprises have chosen this route, adopting a composite approach with polymers to take the lead in large-scale vehicle installations for semi-solid batteries. Specific progress is as follows:

· Weilan New Energy

In December 2023, Weilan's 350 Wh/kg semi-solid oxide battery was equipped in NIO ET7, and semi-solid batteries will be off the production line and supplied to NIO in June 2024. It currently has four bases in Fangshan, Beijing; Liyang, Jiangsu; Huzhou, Zhejiang; and Zibo, Shandong, with a total battery production capacity of 28.2 GWh/year and planned capacity exceeding 100 GWh.

· Qingtao Energy

In March 2024, Qingtao Energy's 300 Wh/kg semi-solid oxide battery was equipped in SAIC Roewe's IM L6 and is expected to be installed in other models such as Marvel R, Roewe, and M6. It currently has a solid-state battery production capacity of 12 GWh and a total planned capacity of 55 GWh.

· Ganfeng Lithium

As early as 2021, Ganfeng Lithium and Dongfeng Motor jointly developed the E70 model equipped with the first-generation solid-state battery, and 50 vehicles were delivered in 2022; in 2023, Ganfeng Lithium's semi-solid battery was equipped in Thalys' electric SUV, SERES-5. The long-term planned capacity exceeds 40 GWh.

· Farasis Technology

The first-generation semi-solid battery was successfully installed in the Lanvin Zhuguang model in 2022; the second-generation semi-solid battery (300-350 Wh/kg) is in the sample testing stage and is expected to enter mass production in 2025.

· Talent New Energy

In collaboration with Changan Automobile, separator-free semi-solid batteries are planned for vehicle verification/testing in 2026. Its first 0.2 GWh semi-solid power battery production line in Chongqing will be commissioned this October.

2.0 Era: Full Solid Sulfide Technology Route Takes Shape

Semi-solid is only a transition; fully solid is the ultimate goal.        

Although semi-solid batteries have achieved industrialization, oxide solid-state batteries still have many issues, particularly with interface contact problems with electrode materials becoming a non-negligible shortcoming, and ionic conductivity posing significant limitations on fast-charging performance. Especially now that traditional liquid batteries are starting to achieve breakthroughs towards 6C charging rates, the development path of oxide electrolytes is uncertain.

The core logic of solid-state batteries remains safety and high energy density, and fully solid-state batteries are the ultimate goal to meet these requirements. Sulfide electrolytes have high conductivity suitable for fully solid-state batteries.

There are four common sulfide material systems, with lithium phosphorus sulfur chloride being the mainstream choice.        

There are four common sulfide-based solid electrolyte systems: lithium germanium phosphorus sulfur (LGPS), lithium silicon phosphorus sulfur chloride (LSiPSCl), lithium phosphorus sulfur chloride (LPSCl), and lithium phosphorus sulfur (LPS). Among them, LGPS has the highest ionic conductivity but extremely high raw material costs and cannot coexist with lithium metal, primarily used for research applications. LPSCl has cost advantages and excellent ionic conductivity, making it the mainstream choice for mass production.

Currently, leading battery manufacturers have focused on deploying sulfide technology routes. Domestically, this includes CATL, BYD, and Huawei, while internationally, it includes Toyota and Panasonic from Japan, Samsung SDI, LG Energy Solution, and SK on from South Korea, and QuantumScape and Solid Power from the United States.

II. Cost Reduction in Materials: From R&D Labs to Mass Production Lines

It is well-known that cost control is a critical factor in the industry. In the current highly mature environment of liquid lithium-ion batteries, despite the high safety and energy density of solid-state batteries, to achieve sustainable industrialization, their costs need to be competitive with liquid batteries.

BOM Costs: Semi-Solid vs. NCM Liquid

According to ICC data, the BOM cost of liquid ternary batteries is approximately 0.33 yuan/Wh. Based on the existing semi-solid NCM + silicon-doped anode system, the BOM cost of oxide semi-solid batteries is approximately 0.35 yuan/Wh. In comparison, semi-solid batteries can compete with NCM liquid batteries.

The cost of fully soid-state batteries depends on the prices of core materials.

According to the fully solid sulfide battery route: high-nickel ternary + lithium metal anode system calculations, sulfide solid electrolytes and lithium metal anodes have the highest value proportion. Currently, the price of sulfide solid electrolytes is about 40,000 yuan/kg, significantly impacting the BOM cost of fully solid-state batteries.

From a cost perspective, fully solid sulfide batteries are still some time away from mass production and are currently in the research and development stage. Subsequent development requires continuous tracking in combination with breakthroughs in materials, equipment, and processes.

III. The Holy Grail of Next-Generation Lithium Battery Technology, Worth the Wait

Solid-state batteries, with their unique solid electrolyte structure and excellent performance characteristics, are regarded as the "Holy Grail" of next-generation lithium battery technology, making them an inevitable choice in the new energy era.

Despite the many technical challenges associated with solid-state batteries, it can be seen that they are in an accelerated research and development stage, and researchers are striving to overcome these obstacles through material innovation and technical optimization. Semi-solid batteries have gradually commercialized, and it is expected that fully solid-state batteries will begin commercial applications in 2027. According to ICC predictions, the demand for solid-state batteries is expected to reach nearly 200 GWh in 2030.

China's lithium battery and new energy industry is vast and occupies an important position globally, with technology reaching world-leading levels. Similarly, the continuous breakthroughs in solid-state battery technology and the acceleration of the industrialization process are worth anticipating.