Lithium-sulphur batteries with minimal electrolyte: potential issues explained
===================================================================
Researchers at HZB have made significant strides in understanding the unique wetting behaviors of lithium-sulphur (Li-S) batteries with lean electrolyte. This study, published in the latest edition of Batteries News, offers valuable insights into the cell failure mechanisms for designing compact Li-S batteries with high energy density.
The study, led by Yan Lu, sheds light on the mechanisms that lead to the rapid ageing and failure of Li-S battery systems. The team designed multilayer pouch cells and operando experiments to observe the dynamic wetting of the pouch cells during charging and discharging in Li-S battery systems.
In their research, the team observed a series of "breath in" and "breath out" wetting behaviors for the first time, correlating with the dissolution and precipitation of sulphur compounds. These unique dynamics differ notably from conventional lithium-ion batteries due to the distinct chemistry of Li-S systems.
The lean electrolyte environment makes complete wetting of electrodes difficult, causing incomplete or heterogeneous electrolyte infiltration in electrode pores and across multilayers. During resting periods, localized unwetted regions develop, especially initially, with only limited improvement over prolonged rests.
However, charging and discharging cycles promote significantly more uniform electrolyte distribution, enhancing electrochemical activation of sulfur and thus increasing cell capacity. This unique wetting behavior impacts cell performance by affecting sulfur utilization and reaction kinetics, influencing aging and failure modes, enabling increased practical energy density, and highlighting the need for optimized charging protocols to promote better electrolyte wetting and maximize capacity.
The insights gained from this study will help increase the energy density of Li-S batteries while maintaining their service life. Li-S batteries can achieve ultrahigh gravimetric energy densities, making them attractive for aerospace, robots, and long-range electric vehicle applications.
To observe how the liquid electrolyte behaves in real-time and how the wetting changes locally in the different layers of a pouch cell over time, the team used neutrons at the Institut Laue-Langevin in Grenoble.
Dr. Liqiang Lu, a postdoctoral researcher, states that the dynamic electrolyte wetting behavior differs significantly from that of conventional Li-ion batteries due to the distinct chemistry of Li-S systems. The discharge/charge processes significantly improve the homogeneity of the electrolyte.
This research is an important contribution to understanding the mechanisms that lead to the rapid ageing and failure of Li-S battery systems, shaping the battery market. With these new insights, researchers can work towards improving the reliability, lifespan, and energy density of lithium-sulphur batteries under lean electrolyte conditions, which is key for their industrial and high-energy applications like aerospace and electric vehicles.
- The unique wetting behaviors observed in lithium-sulphur batteries might lead to improved designs in the industry, particularly for compact batteries with high energy density, given the insights gained from the study in environmental science.
- The financial sector could benefit from increased investment opportunities in the development and optimization of lithium-sulphur batteries, thanks to their potential high energy density, which makes them appealing for aerospace, robots, and long-range electric vehicle applications, as suggested by the study's findings.
- The emergence of advanced technological solutions, such as neutrons to observe real-time electrolyte behavior and changes in a pouch cell's layers over time, can be instrumental in furthering the understanding and optimization of environmental science, specifically in the realm of lithium-sulphur battery systems under lean electrolyte conditions.
