Lithium-sulfur batteries vs. lithium-ion batteries

When it comes to renewable energy technology, batteries play an important role in storing and delivering energy efficiently. Lithium-ion batteries are currently the most widely used batteries in electric vehicles and other applications. However, there is a new contender in the market, the lithium-sulfur battery, that promises better energy density and lower costs.

In this blog post, we will provide a factual and unbiased comparison of lithium-sulfur batteries and lithium-ion batteries based on current research and scientific data.

What are lithium-sulfur batteries?

Lithium-sulfur batteries (Li-S) are a type of rechargeable battery that uses lithium as an anode and sulfur as a cathode. These batteries have higher theoretical energy densities than lithium-ion batteries, which means they can store more energy in the same volume. They also have potential cost advantages as sulfur is a cheaper and more abundant material than the cobalt and nickel used in lithium-ion batteries.

What are lithium-ion batteries?

Lithium-ion batteries (Li-ion) are a type of rechargeable battery that uses lithium ions as the primary material in both the anode and cathode. These batteries have been in the market for over 30 years and are widely used in portable electronics, electric vehicles, and other applications. They have high energy densities, a relatively long cycle life, and a good balance between power and energy density.

Energy Density

One of the biggest advantages of lithium-sulfur batteries is higher theoretical energy density compared to lithium-ion batteries. The specific energy of Li-S batteries can reach up to 2600 Wh/kg, while Li-ion batteries only have a specific energy of around 300-400 Wh/kg. However, currently, Li-S batteries are not able to fully utilize their theoretical capacity, and the practical energy density of the Li-S batteries is about 400-500 Wh/kg, which is lower than Li-ion batteries. Therefore, Li-S batteries still have a lot of research and development to catch up with Li-ion batteries to realize its full potential.

Cycle Life

Cycle life refers to the number of charge/discharge cycles a battery can undergo before its performance begins to degrade. Lithium-ion batteries have a cycle life of around 500-1000 cycles, depending on the operating conditions, while Li-S batteries have a cycle life of around 200-500 cycles. This means that Li-ion batteries still outperform Li-S batteries in terms of cycle life.

Safety

Both Li-S and Li-ion batteries are generally considered safe for everyday use. However, in some scenarios, Li-ion batteries are more prone to overheating and catching fire due to their flammable electrolytes. Li-S batteries, on the other hand, are less prone to catching fire, as their electrolytes are non-flammable. In addition, sulfur is a natural fire retardant, which further enhances safety in case an accident occurs.

Cost

One of the potential advantages of Li-S batteries over Li-ion batteries is their lower cost. Sulfur is an abundant and inexpensive material, which could significantly reduce the cost of Li-S batteries. However, Li-S batteries still have some technical challenges to overcome in terms of energy density and cycle life, which could add to the overall cost. Therefore, it is still unclear whether Li-S batteries will be more cost-effective than Li-ion batteries in the long run.

Conclusion

In summary, lithium-sulfur batteries have the potential to offer higher theoretical energy densities and lower costs in the future. However, current research shows that Li-ion batteries still outperform Li-S batteries in terms of practical energy density and cycle life. Both battery types have their advantages and disadvantages, and it's up to the specific application to determine which battery type is the best fit.

References

1. Bruce, P. G., Freunberger, S. A., Hardwick, L. J., & Tarascon, J.-M. (2012). Li-O2 and Li-S batteries with high energy storage. Nature materials, 11(19), 19-29.
2. Kamath, H., & Shivashankar, S. A. (2019). Lithium-Sulfur Batteries: Challenges and Opportunities. Journal of materials chemistry. A, 7(42), 23894-23921.
3. Nazir, S., Sun, H., Baranchugov, V., & Wang, G. (2019). Understanding Battery Safety in Energy Storage Systems. Chemical reviews, 119(14), 8904-8956.