Intrinsic Safety of Solid-State Electrolytes
- Thermal Stability: One of the core advantages of all-solid-state batteries is that the solid-state electrolytes are non-flammable and offer better thermal stability. This is particularly important for the safety of electric vehicles, as it significantly reduces the risk of thermal runaway under extreme conditions such as high temperatures, thus enhancing overall safety.
- Mechanical Stability: Since there is no liquid electrolyte, all-solid-state batteries are less likely to experience structural changes when subjected to shocks or vibrations, reducing safety risks caused by mechanical damage.
Safety Challenges of Solid-State Batteries
- Lithium Dendrite Growth: While solid-state electrolytes have high mechanical strength, it is still difficult to fully suppress the growth of lithium dendrites and achieve uniform deposition of lithium metal. Lithium can form dendrites on the surface of the anode or even nucleate within the solid-state electrolyte, potentially leading to short circuits and posing a safety risk.
- Toxicity from Breach: If an all-solid-state battery is punctured in an accident, the leaked substances could react with oxygen and then generated toxic gases. This increases the likelihood of severe damage to the vehicle.
- Thermal Stability of Solid-State Electrolytes is Not Absolute: Research has shown that the thermal stability of different types of solid-state electrolytes varies and cannot be generalized.
For example, polymer-based solid-state electrolytes decompose at temperatures above 200℃, oxide-based ones can withstand over 1000℃, and sulfide-based ones can tolerate temperatures above 400℃. In oxides, lithium aluminum germanate phosphate (LAGP) sintered above 1400℃ will undergo thermal runaway reactions upon contact with lithium, whereas lithium lanthanum titanate oxide (LLTO) and solid-state ceramic electrolytes like LLCO do not exhibit thermal runaway. This indicates that not all solid-state electrolytes are stable, and even powders of oxide electrolytes sintered at high temperatures cannot guarantee absolute safety, as stability is related to their own chemical reactivity.
Source: WeChat Official Account—新能源电池包技术
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