Hybrid Li alloy tech beats solid-state battery energy density as Gangfeng starts mass cell production

Ganfeng Lithium, the world's largest lithium metal supplier, has managed to craft a battery with 95% solid electrolyte whose energy density exceeds that of the first solid-state battery generation announced by the likes of Toyota or Samsung.

Gangfeng supplies nearly half of the world's lithium and holds 70% of the local Chinese market, and it is constantly experimenting with new applications, electrode alloys, and electrolyte mixes.

Record solid-liquid battery energy density

Through the use of an innovative lithium alloy, Gangfeng managed to enter mass production of the first battery cells with 95% solid-state electrolyte that come with 650 Wh/kg energy density. For comparison, Toyota, Samsung, and others are preparing to launch commercial solid-state battery products in 2027 with an energy density of 500 Wh/kg, which was previously thought to be the theoretical limit of the technology.

A solid-state electrolyte alone isn't the magic bullet for high energy densities, argues Gangfeng. The most widespread sulfide-based technology comes with double the density of current EV batteries but can still form dendrites if it goes higher. In the new 650 Wh/kg battery, the company left a small portion of the electrolyte in liquid form to ensure cost control and compatibility with current production lines while focusing its efforts on Li electrode alloys that allow higher energy capacity:

Several major challenges need to be overcome in the preparation of lithium alloys: lithium has a low density, and alloying elements are prone to sedimentation, leading to compositional segregation, which can form a hard second phase in severe cases, potentially puncturing the separator or causing processing cracks; the alloy's melting point is higher, making the melting process more difficult to control. Through equipment and process improvements, we have achieved uniform alloying and unexpectedly improved mechanical properties—the alloy's tensile strength, hardness, and Young's modulus are all superior to pure lithium, significantly improving the problem of band breakage during processing and enhancing production stability.

As a result, the Li alloy forming the electrodes of the new 650 Wh/kg battery exhibits a critical current density (CCD) of 50 mA/cm² at a deposition rate of 1 mAh/cm². At typical manufacturing conditions of 3 mAh/cm² deposition, the CCD is kept above 10 mA/cm² and can even hit 12.6 mA/cm², so that the battery can be charged at 3C speeds in 20 minutes.

According to the first solid-state battery performance and classification standard, such a battery would still fall under the hybrid solid-liquid category, as it still has some liquid electrolyte. It still beats solid-state battery energy densities, though, save for those at a prototype stage. The hybrid solid-liquid battery technology is a good stopgap solution, according to CATL, while manufacturers work on lowering the cost and increasing the lifespan of solid-state batteries.

Gangfeng's 650 Wh/kg battery with a hybrid solid-liquid electrolyte will first be going into applications like drones or humanoid robots where energy density is of paramount importance and then, eventually, into EVs. Volkswagen's partner in China, the FAW Group, recently announced that it is testing an electric sedan with solid-liquid battery technology that returned 500 Wh/kg energy density, so the hybrid electrolyte path is proving more viable by the day.

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