While electrification, intelligence, and connectivity are the major development trends in the electric vehicle (EV) market, electrification has been the dominant factor in the first half of the competition, with technological innovation mainly focused on lithium-ion batteries.
Driving range is a key indicator of performance, directly influencing consumers' purchase interest and travel experience. The future development of solid-state batteries will further enhance performance, driving deeper adoption of EVs.
I. Driving Forces behind Solid-State Battery Development
High energy density and high safety are the main drivers for the development of solid-state batteries. While liquid electrolytes have become the biggest limiting factor for the further advancement of lithium-ion batteries, replacing liquid electrolytes with solid-state electrolytes is expected to completely resolve battery safety issues by applying higher-capacity cathode and anode materials.
Compared with traditional liquid lithium-ion batteries, solid-state batteries have advantages such as higher energy density, enhanced safety, and longer lifespan. Therefore, solid-state batteries are regarded as an ideal solution to address lithium-ion battery safety issues and improve energy density, which are widely recognized as the next-generation battery technology. Additionally, solid-state batteries feature a wider operating temperature range, enabling adaptation to various complex climate conditions and expanding market demand.
The solid-state batteries offer superior safety, primarily demonstrated in the following five aspects: 1. High mechanical strength of solid electrolytes that effectively suppresses lithium dendrite growth, reducing the risk of short circuits. 2. Non-flammable and non-explosive features as solid electrolytes are resistant to combustion and explosions. 3. No continuous interfacial side reactions, enhancing long-term stability. 4. No electrolyte leakage or drying issues to eliminates risks associated with liquid electrolyte failure. 5. Uncompromised or improved high-temperature lifespan, which maintains or enhances performance under elevated temperatures.
Higher energy density is another prominent advantage of solid-state batteries. Battery energy density equals working voltage multiplied by specific capacity, and the overall specific capacity follows the "barrel effect," being limited by the lower-performing electrode (cathode or anode).
From the anode perspective, the graphite anode has a theoretical specific capacity of 372 mAh/g, silicon-based anode 4,200 mAh/g, and lithium metal anode 3,860 mAh/g, all significantly higher than cathodes. Therefore, the cathode active materials have become the main bottleneck for further improving lithium-ion battery performance.
All-solid-state electrolytes can not only compatibly pair with high-capacity anode materials (like those above) and conventional cathode systems but also enable high-capacity cathodes, such as high-nickel/ultra-high-nickel ternary cathodes (up to 220 mAh/g), lithium-rich manganese-based cathodes (250–300 mAh/g), which are key to breaking the 400 Wh/kg barrier for power batteries.
Currently, semi-solid-state batteries in real-world vehicle applications have achieved a record energy density of 368 Wh/kg - about 30% higher than mature high-nickel ternary lithium-ion batteries.
II. Solid-State Battery Technology Routes
The current solid-state lithium-ion battery technology adopts a step-by-step iteration strategy. As the liquid electrolyte content gradually decreases, the development path can generally be divided into four categories: liquid (25wt%), semi-solid (5-10wt%), quasi-solid (0-5wt%), and all-solid (0wt%). Among them, semi-solid, quasi-solid, and all-solid batteries are collectively referred to as solid-state batteries.
During the iteration process, the semi-solid and quasi-solid batteries use hybrid solid-liquid electrolytes, while all-solid batteries completely adopt solid-state electrolytes. The anode also evolves from carbon or silicon-carbon anodes to lithium metal anodes. This gradual transition allows for continuous performance improvement while maintaining manufacturability.
Current all-solid-state batteries face technological bottlenecks. The main limitations lie in slower charge/discharge rates and faster capacity degradation. Compared to liquid electrolytes, stronger ion interactions in solid electrolytes result in ion migration energy barriers over 10 times higher than liquids, leading to lower ionic conductivity. Poor solid-solid interfacial contact reduces stability. The "rigid" contact between solids is inherently difficult to achieve full adhesion, and the interfaces are prone to poor contact or even failure. These challenges hinder the commercialization of all-solid-state batteries despite their safety and energy density advantages.
In addition, the cost of solid-state batteries is significantly higher than that of liquid batteries. The cost difference mainly stems from the solid-state electrolyte and electrodes. Solid-state electrolytes require certain rare metal with high prices. High-activity electrode materials (for achieving high energy density) are not yet mature. As a result, the cost of all-solid-state batteries is notably higher than that of existing liquid batteries. Currently, solid-state batteries cost several times more than liquid lithium batteries, posing a major challenge to their commercialization.
III. Analysis of Semi Solid-State Battery Technology Routes
When all-solid-state batteries face high barriers to entry and high cost, some lithium-ion battery companies have opted to first develop semi-solid-state batteries, adopting a hybrid solid-liquid electrolyte as an interim solution, and then gradually reduce the liquid electrolyte content until achieving full solid-state batteries.
At the semi-solid-state lithium-ion battery stage, the cathode and anode systems remain largely consistent with those of liquid batteries. Semi-solid-state lithium batteries offer significant improvements in safety while currently incurring slightly higher costs compared to liquid batteries. Semi-solid-state lithium batteries are particularly well-suited for high-nickel ternary lithium-ion battery systems.
More importantly, the semi-solid-state batteries have already achieved commercial deployment. Multiple automakers - including BYD, SAIC, and NIO - have introduced models equipped with solid-state battery technology, with semi-solid-state batteries already being implemented in production vehicles.
Among the current models featuring semi-solid-state batteries, most are premium C-segment vehicles priced around Yuan 300,000. The primary reason is likely that high-end vehicles are less cost-sensitive, making them better suited for early adoption. In the future, the transition from semi-solid-state to all-solid-state batteries is also expected to begin with premium models.
Based on industry deployment progress and the current adoption rate of semi-solid-state batteries, battery manufacturers are gradually entering mass production between 2023-2024, with initial vehicle installations underway. However, overall installations remain limited during 2023-2025, indicating an early-stage scale. Large-scale commercialization is not expected to occur before 2026-2027 at the earliest.
IV. Analysis of Solid-State Lithium Battery Industrialization Progress
Currently, the industrialization conditions for all-solid-state batteries are not yet mature, and their large-scale application will take even longer. At present, companies and institutions involved in developing solid-state batteries are mainly concentrated in countries such as China, the U.S., Japan, and South Korea.
According to the R&D and mass production plans of global automakers for solid-state batteries, OEMs including Toyota, Nissan, BMW, and Ford are expected to conduct trial runs of vehicles equipped with all-solid-state batteries by2025, with small-scale production projected for 2027-2028. Large-scale commercialization, however, is unlikely to occur before 2030.
Currently, semi-solid-state batteries have gradually entered mass production and application in EVs. If their comprehensive performance proves satisfactory by 2027-2028 and achieves large-scale commercialization, the urgency for all-solid-state batteries may diminish.
V. Development Trends of Solid-State Battery Technology Pathways and Shifts in Resource Demand
During the transition from liquid to solid-state batteries, the solid electrolyte represents the most critical component on the materials side. Meanwhile, cathode and anode materials undergo iterative upgrades toward higher voltage and density. Additionally, conductive additives must be incorporated into the electrodes to reduce internal resistance and enhance electronic conductivity.
The cathode materials for semi-solid and solid-state batteries are trending toward higher voltage, transitioning from nickel-rich ternary systems to new architectures such as ultra-high-nickel and lithium-rich manganese-based systems. The anode initially adopts silicon-carbon composites, with lithium metal systems planned for medium-to-long-term implementation.
Solid-state electrolytes feature multiple coexisting technical pathways, primarily categorized into oxides, sulfides, and polymers.
Sulfide solid electrolytes exhibit the highest ionic conductivity and may become the mainstream route after breakthroughs in manufacturing processes. They combine strength with processability and demonstrate good interfacial compatibility, making them a key focus for corporate investments in patent applications and talent development. However, sulfide materials require extremely stringent production environments, face significant interfacial compatibility issues with cathode materials (prone to side reactions), and remain costly. Japanese companies were early adopters of the sulfide route - as of 2024, Toyota alone holds 68% of global sulfide-related patents.
Oxide electrolytes demonstrate the best stability, moderate conductivity, and the poorest processability, yet they are currently progressing rapidly in development. Oxide electrolytes are compounds containing lithium, oxygen, and other elements (phosphorus, titanium, aluminum, lanthanum, germanium, zinc, zirconium). They offer advantages such as excellent thermal stability, a wide electrochemical window, and high mechanical strength. However, their drawbacks include moderate conductivity, high brittleness, difficult processing, and poor interfacial contact.
In terms of mass production, oxide systems present moderate preparation challenges, making them a preferred route for many startups and domestic companies. By combining with polymers, oxide-based electrolytes are achieving large-scale integration in semi-solid-state batteries ahead of other systems.
Polymer electrolytes are easy to synthesize and process, but their low ionic conductivity at room temperature limits overall battery performance, restricting large-scale application and development. Polymer solid electrolytes are formed by the complexation of polymers and lithium salts, with small amounts of inert fillers added.
Due to advantages such as ease of processing and process compatibility, polymers were the first to achieve commercialization in Europe and represent the most mature technology. However, their low conductivity and narrow electrochemical window limit their compatibility to lithium iron phosphate (LFP) cathodes, resulting in a low performance ceiling. Additionally, they require continuous heating to 60°C during operation. These factors constrain their large-scale adoption.
Moving forward, polymer electrolytes are expected to be combined with inorganic solid electrolytes to leverage the strengths of both, potentially achieving performance breakthroughs in practical applications.
The global solid-state battery industry is primarily distributed across China, Japan, South Korea, Europe, and the U.S.
Japan has the earliest-developed solid-state battery industry, betting on the sulfide route. For example, Japan's Toshiba successfully developed a practical Li/TiS2 thin-film solid-state battery as early as 1983.
South Korea's solid-state battery development strategy focuses on researching lightweight sulfide all-solid-state batteries and high-safety oxide all-solid-state batteries. The main companies driving its industrial system include Samsung SDI, SK On, and LG Energy Solution.
Europe and the U.S. predominantly pursue polymer and oxide solid electrolyte technological routes, emphasizing the development of solid-state lithium metal battery systems.
China mainly adopts the sulfide route, with companies such as CATL, Qingtao New Energy, Grinm Advanced Materials, SEM Corp., and XTC New Energy all focusing on sulfide-based solutions. However, WeLion New Energy is betting on polymer and oxide routes, while Gotion High-Tech is also committed to the polymer route.
Solid-state lithium batteries will significantly enhance the energy density advantage of high-nickel ternary lithium-ion batteries while fundamentally addressing the safety concerns of ternary lithium batteries.
As lithium-ion batteries transition from liquid to solid-state systems, the market share of ternary lithium-ion batteries is expected to substantially increase compared to LFP batteries. This shift will considerably boost nickel demand and also moderately increase cobalt demand.
Upon adopting lithium metal anode systems, solid-state batteries will further drive a significant rise in lithium demand.
In the later stages of solid-state battery development, the cathode material system may transition to lithium-rich manganese-based systems with ultra-high energy density. These cathode materials primarily use manganese and no longer require nickel or cobalt.
Lithium-rich manganese-based cathode materials offer advantages such as high energy density, low cost, and environmental friendliness, with a specific capacity reaching 250-300 mAh/g - the highest among all current lithium-ion battery cathode materials in terms of energy density.
However, lithium-rich manganese-based cathodes still face numerous technical challenges and remain in the early laboratory stage. Their large-scale development is unlikely to occur before 2035 at the earliest, and their commercial viability remains unpredictable at this stage.
VI. Summary
Solid-state batteries, with their revolutionary advantages of high energy density and intrinsic safety, have emerged as a key direction to break through the performance bottlenecks of current liquid lithium-ion batteries and drive the deeper development of the EV industry. Although all-solid-state batteries still face industrialization challenges such as ionic conductivity, interfacial stability, and high costs, semi-solid-state technology has taken the lead in vehicle integration, providing the industry with a valuable transitional solution.
Global OEMs and battery giants are accelerating their deployment across multiple technical routes - sulfides, oxides, and polymers - to compete for dominance in the next-generation power battery market. Looking ahead, as critical milestones are gradually achieved between 2025 and 2030, solid-state batteries will not only reshape the power battery landscape and significantly boost demand for key resources like nickel and lithium but also fully resolve range anxiety and safety concerns. This will lay a solid foundation for the widespread adoption of intelligent and connected EVs, ultimately leading to a profound transformation in the transportation and energy sectors.
