Is a "semi-solid" battery considered a solid-state battery?

In the next 10-20 years, focusing primarily on technological reserves with market applications as a secondary aspect, targeting the luxury car market above 300,000 yuan and the aviation market, will become the main direction for the development of Chinese solid-state battery enterprises.

On April 8th, SAIC's IM Motors unveiled its latest model, the IM L6, which IM claims to be the first in the industry to apply a "quasi-900V ultra-fast charging solid-state battery," capable of achieving a driving range of over 1,000 kilometers. On March 26th, Vivo's latest folding screen phone, the X Fold3, adopted a semi-solid-state battery. Solid-state batteries, which have long been at the conceptual stage, are now entering the application phase in both consumer electronics and automotive power battery fields.

Since its inception, solid-state battery technology has attracted widespread attention due to its enormous potential in cell energy density, safety, and charging/discharging performance. It has always been seen as the next-generation product in the battery field, capable of bringing revolutionary improvements to all products that use batteries. However, the solid-state batteries currently in use are still quite a distance from the goals people hope for.

For instance, the term "solid-state battery" used by IM is highly controversial. The battery's manufacturer, Qingtao Energy, stated that the battery is a semi-solid-state battery, and there has always been controversy within the industry about whether semi-solid-state batteries should be considered solid-state batteries.

The mainstream technological routes for liquid lithium batteries are only lithium iron phosphate and ternary lithium, with other materials such as cobalt oxide, manganese oxide, and titanium oxide batteries being used in very limited scenarios, making the classification relatively clear. In contrast, the technological routes for solid-state batteries are relatively complex, and the classification standards have always been controversial. According to the relatively mainstream classification standards currently, they can be roughly divided into two major categories: all-solid-state and semi-solid-state.

The focus of the controversy is performance.

The main controversy surrounding solid-state batteries at present is whether semi-solid-state batteries should be considered solid-state batteries.

Liu Tao, the co-CEO of IM Motors, responded to the controversy on social media with the question "Is a white horse still a horse?" However, many car manufacturers and battery companies have expressed that there is no generational gap in performance indicators between semi-solid-state batteries and liquid lithium batteries, so it is not advisable to emphasize semi-solid-state batteries in promotions.

These two positions have already clarified the root of the controversy. Those who believe that semi-solid-state batteries belong to solid-state batteries emphasize that the main body of the battery's electrolyte is already a solid material. For example, the battery used by IM has 90% solid and 10% liquid wetting agent in its electrolyte. From the perspective of the electrolyte's properties, it should of course be considered a solid-state battery.

On the other hand, those who believe that the solid-state concept should not be emphasized in promotions argue that solid-state batteries should significantly outperform existing liquid lithium batteries in performance indicators. For instance, the cell energy density should be more than double, and safety and charging/discharging performance should have generational advantages. However, the current semi-solid-state batteries do not meet these standards in performance indicators.As the company with the highest market share in the current power battery industry, CATL has always insisted that solid-state batteries should be the next generation of batteries that adopt a completely new cathode and anode material system, with all-solid-state electrolytes. The current semi-solid-state batteries, which are similar to the cathode and anode materials of liquid lithium batteries, cannot fully utilize the performance of solid-state electrolytes and are a typical transitional technology.

Over the past few years, the concept of solid-state batteries has been widely disseminated, forming a unified perception in consumers' minds that solid-state batteries have a very leading performance and are technologically capable of overturning existing liquid lithium batteries. However, this perception is aimed at all-solid-state batteries that use completely new cathode and anode materials, not semi-solid-state batteries that do not have an essential difference from existing lithium batteries.

From the perspective of performance indicators, the semi-solid-state batteries that are currently mass-produced and installed in vehicles, whether it is NIO's 150KWh battery or Zhiji L6's semi-solid-state battery, have a cell energy density of about 350Wh/KG, which is less than a 20% increase compared to the highest level of ternary lithium batteries currently available.

At the battery pack level, CATL's Kirin battery can achieve a maximum of 140KWh of electricity, which has been installed in the Ji Krypton 009 in 2022. The maximum capacity of the lithium iron phosphate battery pack is also close to 100KWh. The second-generation Blade Battery that BYD plans to release in August 2024 will also greatly increase the cell energy density, supporting BYD's pure electric models to achieve a maximum range of more than 1000 kilometers.

Even the safety advantage that solid-state batteries have always emphasized is not obvious compared to existing batteries. Semi-solid-state batteries have significantly reduced the proportion of flammable substances in the electrolyte, so the risk of fire has been greatly reduced. Compared with liquid lithium batteries five years ago, their safety advantage is very significant, but compared with batteries released in the past two or three years, the advantage is not obvious. The latest liquid lithium batteries, through the application of various battery pack safety technologies, can mostly achieve only smoking, not catching fire. For consumers, if there is a serious problem with liquid lithium batteries and semi-solid-state batteries, the final result is the total loss of the vehicle, and the insurance pays.

The controversy over whether semi-solid-state batteries are considered solid-state batteries is not whether the electrolyte material is solid or not, but whether the battery performance has reached the high expectations of consumers for solid-state batteries. From this perspective, the current semi-solid-state batteries are indeed not considered solid-state batteries.

Cost is the biggest stumbling block.

The development of solid-state batteries is undoubtedly based on technological breakthroughs, and the research and development of new cathode and anode materials and electrolyte materials are the most critical links. The news about solid-state batteries in the past period has also focused on this.

For example, on April 7, Chongqing Tai Lan New Energy Company released a full solid-state battery that meets automotive standards. The cathode uses lithium-rich manganese-based materials, the anode uses lithium-containing metal, the electrolyte uses oxide solid-state electrolytes, and the packaging uses aluminum plastic film soft packaging. The cell energy density measured in the laboratory reached 720Wh/KG, which meets people's expectations for solid-state batteries in terms of both material system and performance parameters.However, like the solid-state battery samples released by overseas companies such as LG, SKI, and Toyota, this battery, despite its pleasing performance, remains at the laboratory prototype stage, with numerous obstacles to overcome before industrial mass production. This includes engineering and process issues that will take several years to address one by one.

Whether it's material technology or engineering processes, all technical issues in the development of solid-state batteries have already found their resolution paths. The real barriers in front of solid-state batteries are cost and application challenges.

The current technological routes for solid-state batteries require the use of materials with very high costs. For instance, the cost of oxide electrolytes is at least several hundred yuan per kilogram, while the cost of lithium hexafluorophosphate, a key raw material for existing electrolytes, is only a few dozen yuan per kilogram. The cost of processing it into an electrolyte does not exceed one hundred yuan per kilogram, showing a significant disparity.

Taking NIO's 150KWh semi-solid-state battery pack as an example, the cost of a 150KWh battery pack is equivalent to the price of a NIO ET5, approaching 300,000 yuan, which is three times the price of a regular battery pack. This is just for a semi-solid-state battery; if it were a fully solid-state battery, the cost would inevitably be even higher.

As mass production scales up, the cost of solid-state batteries will certainly decrease rapidly. However, the most optimistic estimates within the industry suggest that it will take no less than 20 years to approach the current cost of liquid lithium batteries.

Moreover, the cost of liquid lithium batteries continues to be optimized. By 2024, the cell cost of lithium iron phosphate batteries has already dropped below 0.4 yuan/Wh, and ternary lithium batteries have dropped below 0.5 yuan/Wh. In an overall market environment of oversupply, it is highly likely that the cost will approach the 0.3 yuan/Wh threshold within the year.

The lower the cost of liquid lithium batteries, the greater the resistance to the application of solid-state batteries. Even if fully solid-state batteries are applied within the next 5-10 years, they will only be concentrated in a very small number of high-end luxury product lines. Car manufacturers may gradually form a configuration model where solid-state batteries are used only for flagship products with high gross margins, while products that truly drive sales will continue to use batteries made from ternary lithium and lithium iron phosphate materials. This is similar to the era of fuel vehicles, where there were both supercars and luxury cars with eight, ten, or twelve-cylinder engines, as well as mass-market models with four-cylinder engines.

And indeed, mainstream car manufacturers are currently operating in this way. Major car manufacturers in Europe, America, and Japan are heavily investing in the research and development of solid-state batteries while signing supply contracts with current power battery suppliers that reach tens of GWh and tens of billions of dollars. These contracts are mostly delivered starting from 2025-2026 and last for about five years. Once such a scale is reached, car manufacturers will not be able to switch technology routes at will, just as it is currently difficult for European and American car manufacturers to switch from fuel vehicles to new energy vehicles.

Once car manufacturers establish a model that combines solid-state batteries with liquid batteries in a high-low configuration, the large-scale application of fully solid-state batteries will become increasingly difficult. This is because the entire solid-state battery industry chain will become more adapted to this small-scale, high-gross-margin model, entering a comfortable zone of being small and beautiful, and losing the motivation to compete with liquid lithium batteries in terms of cost and price.

Currently, Toyota is the global leader in solid-state battery research and development, temporarily leading in terms of technology patents. However, China has a greater number of companies investing in the field of solid-state batteries. Whether it's start-ups like Beijing Weilan New Energy, Qingtao Energy, or Chongqing Tailan New Energy, or large existing battery industry companies like CATL, Ganfeng Lithium, and Tianci Materials, they are all heavily investing in the field of solid-state batteries. China is in the global first tier in terms of research and development progress in solid-state batteries.However, one should not easily claim breakthroughs in solid-state batteries. Technological breakthroughs are just the first step; mass production, cost, and application—each subsequent challenge is fraught with difficulties. Leveraging China's vast market size and its leading position in the global battery industry chain, Chinese companies possess a unique and innate advantage. Over the next 10 to 20 years, focusing primarily on technological reserves and secondarily on market applications, targeting the luxury car market above 300,000 yuan and the aviation market, will become the main direction for the development of Chinese solid-state battery enterprises.