Summary of Key Points
All-solid-state batteries are currently the “star technology” in the field of new energy vehicles. However, Wang Deping, the chief scientist at FAW Group, clarified two common misconceptions during a forum:
1. The safety of all-solid-state batteries is relative; once thermal runaway occurs, their destructive power far exceeds that of liquid-state batteries.
2. A wide theoretical temperature range does not necessarily mean good performance in low temperatures; they perform worse than liquid-state batteries at -20°C.
The industry’s mainstream approach focuses on sulfide-based batteries, with plans for small-scale production by 2027 and achieving an energy density of over 400 Wh/kg (about 15% higher than current liquid-state batteries) by 2030. Despite the promising prospects, there are still three major challenges to overcome: gaps in understanding the underlying mechanisms, the need for innovative manufacturing processes, and issues with vehicle integration. Nevertheless, significant breakthroughs have been made across the entire production chain. The future development of all-solid-state batteries will involve three generations of commercial products, with AI and various applications (such as low-altitude aircraft and robots) playing a key role in their widespread adoption.
Detailed Analysis
1. All-solid-State Batteries Are Not the “Perfect Solution”: Two Misconceptions Need to Be Corrected
Many people believe that all-solid-state batteries are absolutely safe, but Wang Deping argues otherwise:
- Safety is Relative, and Thermal Runaway Can Be Destructive: The decomposition temperature of solid electrolytes (600°C) is much higher than that of liquid electrolytes (60°C), and they are less susceptible to lithium dendrite penetration. However, in the event of a thermal runaway (e.g., due to a severe impact), the destructive power is ten times greater than that of liquid-state batteries. This is caused by a tenfold increase in gas generation, mass emission, and a hundredfold acceleration of the reaction, leading to a dramatic rise in temperature. FAW’s testing required access to national nuclear test facilities because standard laboratory equipment was insufficient. As a result, vehicles using all-solid-state batteries will need to have additional high-strength insulation layers, which will increase costs.
- Poor Performance at Low Temperatures: Although solid electrolytes theoretically do not experience the freezing issues of liquid electrolytes, at -20°C, ion conductivity drops significantly, reducing charging and discharging efficiency. One solution is to use an active heating system that maintains the temperature between 40-45°C, but this adds energy consumption and increases complexity.
In summary, all-solid-state batteries are less likely to catch fire, but once they do, the consequences can be more severe; they perform better in theory than in reality at low temperatures.
2. Why Are Sulfide-Based Batteries the Industry’s Favorite Choice for Mass Production?
There are four main technical approaches to developing all-solid-state batteries, and sulfides are the preferred option for automakers such as FAW, CATL, and BYD:
- Advantages of Sulfides: They offer ion conductivity close to that of liquid electrolytes and better interface compatibility, making them more suitable for automotive applications.
- Disadvantages of Other Approaches: Oxide-based batteries (represented by SAIC) have high stability but poor conductivity; polymer-based batteries have simple manufacturing processes but poor performance at room temperature; halide-based batteries are promising but require expensive raw materials.
- Future Trend: A combination of different technologies (e.g., sulfides and halides) is likely to become the standard, as no single approach can balance performance and cost effectively.
3. Are We Far from Large-Scale Production?
There are still three major hurdles to overcome before all-solid-state batteries can be widely used in vehicles:
- Unresolved Mechanisms: The long-term behavior of the “solid-solid interface” (where the electrode meets the electrolyte) is not well understood, and repeated cycles can lead to instability and reduced battery life.
- Innovative Manufacturing Processes: Although the manufacturing differences between all-solid-state and liquid-state batteries are initially thought to be small (20%-30%), they actually differ by 50%. For example, sulfide-based batteries require high-pressure processing (600 MPa), which poses significant challenges for equipment sealing and batch consistency. Additionally, low yields in processes like coating and stacking can lead to short circuits.
- Vehicle Integration: The large expansion rate of all-solid-state batteries during charging and discharging requires specialized design and additional protective layers, increasing the weight and cost of battery packs.
In summary, many engineering issues need to be resolved before these batteries can be mass-produced.
4. Good News: Significant Progress Across the Production Chain
Despite the challenges, the industry has made rapid progress in recent years:
- Material Advances: High-nickel cathodes can retain 84% of their capacity after 1000 charge-discharge cycles, and silicon-carbon anodes have also shown stability. Sulfide electrolytes are now being produced in large quantities with satisfactory conductivity.
- Domestication of Manufacturing Equipment: Key equipment (such as nano-suspension mixing and high-pressure processing) has been localized, solving issues related to material agglomeration and interface separation, improving yields in pilot production lines.
- Safety Tests Passed: 60-100 Ah all-solid-state batteries (the same size as current liquid-state batteries) can remain flame-free at 200°C for 30 minutes—this was not possible just two years ago.
- Standardization and Patents: Nearly 7,000 patents have been applied for in China, and the Ministry of Industry and Information Technology is revising 10 national standards, which will help end the current lack of industry norms.
These developments indicate that all-solid-state batteries have moved from the laboratory stage to pilot production.
5. Future Development Directions
Wang Deping outlined a clear commercialization roadmap:
- Three Generations of Batteries:
- **First Generation (2025-2027): Low-silicon/graphite anodes, energy density of 300-350 Wh/kg; small-scale production by 2027.
- **Second Generation (2027-2030): High-silicon anodes, energy density exceeding 400 Wh/kg, significantly improved range.
- **Third Generation (after 2030): Lithium-metal anodes, energy density over 500 Wh/kg, solving range concerns.
- AI-Driven Research: AI can accelerate material selection and simulation experiments, potentially halving the research and development time.
- First Applications in Specific Areas: These batteries will first be used in low-altitude aircraft, specialized equipment, and robots, where safety and high energy density are critical. Only later will they become more common in cars and energy storage applications.
In conclusion, all-solid-state batteries represent the future of new energy vehicles, but they are not a panacea. Many challenges remain to be addressed. However, with rapid industry progress, we can expect to see vehicles equipped with these batteries on the roads by 2027. In just a few more years, range concerns may become a thing of the past.