Electrolyte

Solid-state batteries typically use solid materials such as ceramics, glass, or polymer materials as electrolytes. These solid materials have very stable structures and are not easily decomposed or deteriorated at high or low temperatures, making them less prone to thermal runaway. However, their conductivity is relatively low, and the interfacial contact still requires further optimization.

Lithium-ion batteries usually use liquid or gel-like electrolytes made from organic solvents dissolved with lithium salts. While liquid electrolytes have ionic conductivity and support high current charging and discharging, they also come with a certain risk of leakage. When the battery is subjected to physical damage or overcharging, the liquid electrolyte can easily lead to situations such as fire or explosion.

Energy Density

The energy density of solid-state batteries in practical applications ranges from 300 to 400 Wh/kg. If the technical challenges related to the ionic conductivity of solid electrolytes and interfacial stability can be overcome, it is expected to gradually increase to the theoretical value of 500 Wh/kg.

Lithium-ion batteries, limited by the characteristics of liquid electrolytes and graphite anodes, typically have an energy density of around 150 to 250 Wh/kg in practical applications. Some lithium-ion batteries that use more advanced materials and processes can achieve energy densities of up to 300 Wh/kg.

Capacity

Some laboratory solid-state batteries have achieved a capacity that is 20-30% higher than that of lithium-ion batteries, and they exhibit slower degradation during long-term use. This technology is not yet mature and is currently limited by manufacturing materials and processes, leaving significant room for improvement.

The standard capacity of lithium-ion batteries typically ranges from 1000 mAh to 5000 mAh, while high-performance lithium-ion batteries can reach up to 8000 mAh. As the number of charge and discharge cycles increases, the capacity of lithium-ion batteries gradually declines, and their long-term retention rate is not as good as that of solid-state batteries.

Safety

The solid electrolyte inside solid-state batteries does not leak, is non-flammable, has good thermal stability, and can withstand a certain degree of physical damage, effectively reducing the risk of fire and explosion. Furthermore, solid-state batteries have a more stable structure, which is less likely to suffer performance degradation or safety issues due to electrolyte decomposition or electrode material deterioration. They also have a relatively lower dependence on protective systems.

In contrast, the liquid electrolyte inside lithium-ion batteries poses an increased risk of leakage when subjected to external impacts. Liquid electrolytes are flammable and can easily cause short circuits; they are prone to decomposition in high-temperature environments, leading to thermal runaway and potentially resulting in fire or explosion. Additionally, lithium-ion batteries heavily rely on battery management systems to enhance their safety.

Lifespan

Solid-state batteries have a long cycle life, capable of exceeding several thousand cycles. They exhibit strong durability and can maintain a high capacity and performance even after prolonged use.

In contrast, lithium-ion batteries have a relatively shorter lifespan, allowing for approximately 800 to 1500 charge and discharge cycles. Higher-performance lithium-ion batteries can exceed 2000 cycles. Additionally, after long-term use, their capacity retention decreases due to the decomposition and deterioration of internal materials, which has a certain impact on performance.