Solid-Liquid Hybrid Battery

The solid-liquid hybrid battery (semi-solid-state battery / hybrid solid-liquid battery) serves as a vital transitional solution in the evolution of EV traction battery technology from conventional liquid lithium-ion batteries to all-solid-state batteries. While leveraging established liquid battery supply chains and manufacturing processes, it significantly enhances energy density and safety performance by incorporating partial solid electrolytes, solid electrolyte coatings, or high-concentration gel electrolytes—making it a mainstream technical pathway to balance long operating range and high safety for premium new energy vehicles.

Core Working Principle and Technical Characteristics

The defining characteristic of solid-liquid hybrid batteries lies in "liquid-solid coexistence and synergistic optimisation."

In this cell chemistry, the electrolyte is not wholly solid; solid electrolyte materials such as oxides, sulphides, or polymers are typically applied to the cathode, anode, or separator surfaces, while retaining a minimal volume (typically under 5% to 10% by mass) of liquid electrolyte or gel to maintain efficient ion transport pathways. This architecture effectively resolves the high solid-solid interface impedance challenge encountered in all-solid-state batteries. Concurrently, by substantially cutting down on flammable liquid electrolytes, the risk of thermal runaway under extreme conditions—such as nail penetration, high ambient temperatures, and overcharging—is effectively suppressed.

Application Scenarios and Market Value

Solid-liquid hybrid batteries are widely adopted in current mid-to-high-end battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs).

Ahead of full-scale commercial mass production of all-solid-state batteries, solid-liquid hybrid batteries—leveraging viable manufacturing costs and notably higher energy densities (routinely achieving over 350 Wh/kg in production grade)—enable carmakers to push single-charge driving ranges to new heights without incurring prohibitive cost increases, effectively addressing consumer range anxiety.

Safety Guidelines and Physical Limitations

Solid-liquid hybrid batteries must strictly not be misrepresented as inherently fail-safe "all-solid-state batteries" through exaggerated marketing, nor subjected recklessly to destructive limit testing:

Although the safety profile of solid-liquid hybrid batteries is markedly superior to conventional liquid lithium-ion units, liquid components are still present within the cells. In the event of severe physical impacts or puncture collisions, latent thermal runaway risks remain and must not be taken lightly.

Subjecting the vehicle to prolonged ultra-fast DC charging or hard, aggressive driving is strictly prohibited if the traction battery thermal management system malfunctions or coolant circulation is compromised: 

Solid-liquid hybrid batteries demand strict operating temperature thresholds. Extended exposure to high operating temperatures under poor heat dissipation will not only accelerate electrolyte ageing and interfacial side reactions, but also cause irreversible battery capacity degradation.