New research shows similarities between solid-state and liquid electrolytes for safer and more efficient batteries

Exciting new research from the McKelvey School of Engineering at Washington University in St. Louis has revealed that a solid-state electrolyte bears a striking resemblance to its liquid counterpart. This is a significant breakthrough as it opens up the possibility of designing more efficient and safer solid-state batteries using reliable mechanistic knowledge.

According to Peng Bai, an assistant professor of energy, environmental and chemical engineering, the similarities between the two types of electrolytes are surprising. This finding provides valuable insights that can be applied to the design of solid electrolytes. Prior to this study, solid electrolytes, particularly the ceramic variants examined in this research, were regarded as fundamentally different from liquid electrolytes.

As batteries power much of our daily lives, any advances in battery technology will have a far-reaching societal impact. Developing a full solid-state battery is a promising avenue, with the electrolyte at its core being a crucial component that facilitates ion movement between electrodes. By replacing the traditional liquid electrolyte with a solid electrolyte coupled to a metal electrode, the amount of energy stored in the battery can be increased, while simultaneously increasing the safety of the device.

Despite the potential benefits of solid-state batteries, there is a growing concern over the critical current density (CCD) barrier that hinders their further development. Dendrites, tree-like structures that grow beyond the CCD threshold, are a major cause of battery failure. The reported CCDs are relatively low, limiting fast charging and compromising the efficiency of solid-state batteries.

To address this issue, Peng Bai, the principal investigator of a research project at the McKelvey School of Engineering, is investigating the underlying physics of CCD and how it changes under different operating conditions. In a recent study published in ACS Energy Letters, Bai and his team discovered that the thickness of the solid electrolyte is closely linked to the magnitude of CCD. They found that reducing the thickness of the solid electrolyte can help overcome the CCD barrier and prevent dendrite growth and internal short-circuiting.

The study involved cutting a standard pellet into smaller pieces and testing them using an electroanalytical technique. This approach helped to obtain more reliable results and meaningful statistics.

According to Rajeev Gopal, the first author of the paper and a doctoral student in Bai’s lab, the study can shed light on the mysterious phenomenon of dendrite initiation at the CCD and help predict and mitigate their growth. This will increase the feasibility of solid-state electrolytes in real-world batteries, making them a real game-changer in battery technology.

Source: Washington University in St. Louis

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