In the context of the global energy transition and the rapid development of electric vehicles, advances in battery technology have become a key force driving this change. Recently, Professor Ma Cheng's team at the University of Science and Technology of China has made a major breakthrough in the field of all-solid-state batteries, developing a new sulfide solid-state electrolyte Li7P3S7.5O3.5 (LPSO), which not only shows significant advantages in performance, but also achieves a major breakthrough in cost control, paving the way for the commercialization of all-solid-state batteries.
Challenges and opportunities for all-solid-state batteries
All-solid-state lithium batteries (ASSLB) are widely considered to be the future development direction of battery technology due to their high safety and high energy density. However, its commercialization has been limited by the high cost and performance bottlenecks of solid-state electrolytes. Conventional sulfide solid electrolytes, despite their superior performance, typically cost more than $195 per kilogram, much higher than the $50 per kilogram required for commercialization. This cost barrier makes the widespread adoption of all-solid-state batteries a huge challenge.
Innovative breakthrough: a new sulfide solid electrolyte LPSO
Professor Ma Cheng's team at the University of Science and Technology of China has developed a new sulfide solid electrolyte LPSO through innovative research. This material not only retains the inherent advantages of sulfide solid electrolytes, but also achieves a major breakthrough in cost. The raw material cost for LPSO is only US$14.42 per kilogram, well below the threshold of US$50 per kilogram required for commercialization. This cost advantage makes LPSO have great potential for commercial applications in all-solid-state batteries.
Superior performance: low density and high compatibility
The density of LPSO is only 1.70 g/cm³, which is significantly lower than that of oxide (usually above 5 g/cm³) and chloride (about 2.5 g/cm³) solid electrolytes. This gives LPSO significant advantages in terms of reducing battery weight and increasing battery energy density. In addition, LPSO exhibits excellent anodic compatibility. Its symmetrical battery composed of lithium metal can achieve a stable cycle at room temperature for more than 4200 hours, while the all-solid-state pouch battery composed of silicon anode and high-nickel ternary cathode still has a capacity retention rate of 89.29% after 200 cycles at 60°C.
Figure: The Chinese Academy of Sciences has developed a new sulfide solid-state electrolyte with low cost and good performance
Research significance: Promote the commercialization of all-solid-state batteries
Professor Ma's research has not only made a breakthrough in technology, but also provided the possibility of commercialization of all-solid-state batteries in terms of economy. According to the reviewers, LPSOs "combine low density, good anode compatibility, and strong cost competitiveness" and that all-solid-state batteries composed of LPSOs have "excellent cycling performance". The publication of this achievement marks a solid step forward in all-solid-state battery technology and provides a new direction for the future development of battery technology.
Challenges in the commercialization of all-solid-state battery technology
The commercialization of all-solid-state battery technology is challenging, but it is expected that these challenges will be overcome as the technology continues to advance and the market demand grows. By optimizing solid-state electrolyte materials, improving solid-solid interface contact, reducing material costs, and simplifying production processes, all-solid-state batteries are expected to achieve large-scale commercial applications in the future, promoting the development of battery technology in the direction of higher performance and higher safety.
All-solid-state batteries (ASSLB) are considered to be the "ultimate form" of battery technology, offering advantages such as high energy density, high safety, and long life. However, there are still many technical challenges in its commercialization process. The following is a detailed analysis of the main technical challenges faced in the commercialization of all-solid-state batteries:
1. Solid electrolytes have low ionic conductivity
The ionic conductivity of solid-state electrolytes is a key factor affecting the charging and discharging speed of all-solid-state batteries. Compared with liquid electrolytes, solid electrolytes have a higher ion mobility energy barrier, resulting in lower ionic conductivity. This makes the all-solid-state battery charge and discharge slower and the capacity decays faster.
2. Poor stability of solid-solid interface
In all-solid-state batteries, the solid-solid interface contact and stability between the solid-state electrolyte and the electrode material are poor. Unlike solid-liquid contact, solid-solid contact is a "hard" contact that is difficult to fit adequately, resulting in reduced lithium ion channels and stress build-up. In addition, lithium metal reacts easily after contact with the solid electrolyte and diffuses into the electrolyte, resulting in rapid decomposition of the electrolyte surface.
3. Lithium dendrite growth problems
Solid electrolytes with high mechanical strength are still difficult to completely inhibit the growth of lithium dendrites. Penetration of lithium dendrites can cause short circuits in the battery, which can lead to safety concerns. Studies have shown that even inorganic solid-state electrolytes with high shear modulus cannot completely prevent the penetration of lithium dendrites in solid-state electrolytes.
4. High cost of materials
At present, some raw materials for solid-state batteries have not been mass-produced, and the cost of battery electrode materials is high. For example, sulfide solid-state battery materials with graphite anodes cost the most, reaching $137.9/kWh, much higher than traditional lithium batteries at $93.2/kWh. In addition, the synthesis of sulfide solid electrolytes requires the use of large quantities of expensive lithium sulfide (not less than US$650 per kilogram), which is also an important factor limiting its commercialization.
5. The production process is complex
The production process of solid-state batteries is complex and lacks specific equipment. For example, sintering, vacuum, drying room, specific atmosphere and other links will increase the manufacturing cost of solid-state batteries. In addition, solid-state batteries are also expensive to assemble and process, which further limits their commercialization.
6. Cycle life and stability of the battery
During the cycling process of all-solid-state batteries, the electrochemical reaction between the positive material of the cathode and the lithium metal anode causes volume changes, which affects the stability of the solid-solid interface. Continuous stress accumulation can lead to micron-scale cracks in the cathode and solid-state electrolyte layers, and the contact between the cathode and the electrolyte deteriorates, exacerbating battery performance degradation.
7. Risk of thermal runaway
Although solid-state electrolytes are inherently non-flammable, the risk of thermal runaway in all-solid-state batteries cannot be completely avoided. The problem of thermal decomposition and oxygen production of ternary cathode materials with high specific volume still exists in all-solid-state batteries, and lithium metal may grow dendrites in the solid-state electrolyte, and continuous growth may penetrate the electrolyte, and the battery may short circuit and generate a large amount of heat and increase the temperature, which will eventually lead to thermal runaway of the battery.
8. The challenge of complex solid-state electrolytes
Although composite solid-state electrolytes can theoretically improve ionic conductivity, they still face many challenges in their practical applications. For example, although inorganic particle-filled composite solid electrolytes can significantly improve the ionic conductivity at room temperature, their stability and compatibility in actual batteries still need to be further verified.
Summary and outlook
This breakthrough of USTC in the field of all-solid-state batteries not only demonstrates China's innovation ability in the field of battery technology, but also provides new impetus for the development of global battery technology. With the continuous advancement of technology and the growth of market demand, new sulfide solid electrolytes such as LPSO are expected to play a more important role in future battery manufacturing, driving the entire industry to develop in the direction of higher performance and lower cost. The research results of Professor Ma Cheng and his team have undoubtedly injected new vitality into the commercialization process of all-solid-state batteries, and also provided strong support for the global energy transition and the development of electric vehicles.
