The competition between semi-solid and all-solid battery routes is essentially a choice of industrial priorities: semi-solid batteries, with their practicality, reduce the risk of change and are suitable for the current Chinese market. All-solid-state batteries anchor the future with performance, aligning with the technological breakthrough strategies of Japanese and South Korean battery manufacturers
The large-scale commercialization of solid-state batteries in China still faces technical bottlenecks such as high interface impedance and high costs. It requires a dual-wheel drive of "technological breakthroughs + industrial ecosystem strength" to transform laboratory advantages into market discourse power
By Qu Haoyuan
Solid-state batteries, as the core technology direction of the next-generation lithium batteries, compared with liquid lithium batteries, can offer greater energy density, significantly enhance endurance, notably improve safety, prevent liquid electrolyte leakage, and reduce the risk of thermal runaway. At the same time, they have a wider operating temperature range and more outstanding adaptability in extreme environments. It has broad application prospects in fields such as new energy vehicles, low-altitude economy and consumer electronics.
At present, the large-scale application of solid-state batteries still needs to solve several problems, mainly including material technology bottlenecks, engineering mass production bottlenecks, and high costs.
The industrialization breakthrough of solid-state batteries requires multi-dimensional collaboration. First, it is necessary to enhance policy support and guidance, driving the industrialization of solid-state batteries through the formulation of industry standards, financial subsidies, and research and development support. Second, battery and material manufacturers should accelerate material and process innovation. On the one hand, the material end needs to break through technical bottlenecks through material system innovation and interface optimization. On the other hand, the manufacturing process and equipment end need to be innovated and upgraded, and at the same time, the manufacturing process needs to be optimized to improve yield and production efficiency. Third, expand application scenarios to promote cost reduction and large-scale implementation. Accelerate the early expansion of application scenarios such as robots and eVTOL, promote large-scale cost reduction of solid-state batteries, and then accelerate the commercial application in the field of new energy vehicles.
Both semi-solid and all-solid lines run in parallel
In terms of technical routes, the mainstream solid electrolyte materials include four major categories: sulfides, halides, oxides, and polymer electrolytes. Different solid electrolytes have their own advantages and disadvantages, and the industry is still exploring the most suitable technical route for the mass production of solid-state batteries.
Specifically, polymers have good wettability and processing performance, but poor oxidation resistance, low electrical conductivity, and poor intrinsic safety. They can be complexed with lithium salts to improve electrical conductivity or used as the framework or solid-solid interface transition layer of granular inorganic solid electrolytes. Oxides have good intrinsic safety, relatively good chemical stability, and relatively low manufacturing costs, but they have poor processing performance, low electrical conductivity, and a narrow electrochemical window. In practical applications, they can be used as the core electrolyte layer of semi-solid batteries. Sulfides have high room-temperature electrical conductivity and good mechanical processing performance, but they have poor chemical stability and high manufacturing costs. Currently, they are mostly used as core electrolyte layers in the development of all-solid-state battery solutions. The ionic conductivity of halides can also meet the application requirements, and they have relatively low costs, good flexibility, and a wide electrochemical window. Currently, they are mostly used as cathode coating materials for solid-state batteries.
From the current perspective of technical route selection, the mainstream layout route for all-solid-state batteries is sulfide and halide composite electrolytes, which have relatively high ionic conductivity and other properties. However, issues such as poor chemical stability and high cost make their large-scale application rather difficult. Semi-solid batteries mostly use oxide and polymer composite electrolytes, which are relatively low in cost and easy to be industrialized, but have a lower upper limit of performance.
In addition, in terms of battery forms, semi-solid batteries and all-solid batteries are currently operating in parallel. Some viewpoints hold that semi-solid batteries are transitional products. Some viewpoints hold that semi-solid batteries are not a transitional route but an independent one, as their design goal is not to serve all-solid batteries but to directly meet the demands of downstream power and energy storage customers.
The competition between semi-solid and all-solid battery routes is essentially a choice of industrial priorities: semi-solid batteries, with their practicality, reduce the risk of change and are suitable for the current Chinese market. All-solid-state technology anchors the future with its performance ceiling, aligning with the technological breakthrough strategies of some battery manufacturers.
For enterprises related to the industrial chain, it is necessary to balance resource investment between the commercialization of semi-solid batteries in the short term and the ultimate goal of all-solid-state batteries in the long term. Taking semi-solid batteries as the vanguard, they should also make strategic reserves for all-solid-state batteries to fully achieve technological and mass production breakthroughs.
There are still difficulties in industrialization
The main challenges faced by the large-scale industrialization of all-solid-state batteries lie in factors such as material performance and interface contact issues, complex manufacturing processes, and an incomplete industrial chain, which lead to high costs.
From the perspective of materials, all-solid-state batteries still face many challenges in terms of material technology such as electrolytes, cathodes, and anodes, as well as in solid-solid interface contact.
In terms of electrolytes, sulfide electrolytes are the mainstream electrolyte technology route for all-solid-state batteries. This is due to their high room-temperature ionic conductivity, which is close to that of liquid electrolytes, and their excellent mechanical processing performance. However, its poor chemical stability and high cost make its large-scale application rather difficult.
Taking the crude powder electrolyte system of LiPSCl as an example, its main raw materials include lithium sulfide, phosphorus pentasulfide and lithium chloride. Among them, the mass proportion of lithium sulfide in the raw materials is over 30%, and its proportion in the cost structure is as high as 82%. The current production cost of lithium sulfide is relatively high, with a market price ranging from 2 to 3 million yuan per ton. This is mainly due to the unstable chemical properties of lithium sulfide, which readily reacts with water and oxygen in the air. Li2S undergoes hydrolysis to form LiHS and LiOH, and further hydrolysis generates the toxic gas H2S, posing a significant production safety risk. Regarding the production environment and storage and transportation conditions