Researchers worldwide are exploring ways to improve the performance of electrolytes within rechargeable lithium-ion batteries, which power everything from phones and laptops to electric vehicles.
The electrolyte of a lithium-ion battery is a mixture of electrically charged particles (ions) that allows the transfer of electrical charge in the battery. The electrolyte facilitates the reversible movement of ions needed during repeated cycles of battery use and recharging.
Researchers in China have reviewed new options for conductive medium heat in the battery core. The research, titled “Bis(fluorosulfonyl)imide-based electrolyte for rechargeable lithium battery: A perspective,” was published in the Journal of Power Sources Advances.
Identifying problems with electrolytes
The properties of electrolytes are highly dependent on the identity and chemical nature of their negatively charged ions (anions). These support the transfer of positively charged lithium ions through the electrolyte in either direction.
Existing electrolytes come with some significant problems, however, including chemical instability, sensitivity to water, volatility and flammability. These problems drive research into alternative anions that could mitigate the problems and improve battery performance.
A promising alternative that is being explored for a new generation of batteries is the bis(fluorosulfonyl)imide (FSI) anion, which contains nitrogen, sulphur, oxygen and fluorine atoms.
FSI has gained special attention in the battery field due to the unique physical, chemical and electrochemical properties of FSI-based electrolytes.
Improving battery performance using FSI
New anions are of prime importance for the development of robust electrolytes required by high-performance LIBs and RLMBs. The bis(fluorosulfonyl)imide (FSI) anion has received increasing attention in the battery field since its invention in the 1990s, and currently, there are more than 600 published scientific papers related to salts based on FSI.
The authors of the paper reviewed the progress of different approaches to making FSI-based electrolytes and evaluated their performance in a number of prototype lithium-based battery systems. Then, they summarized the advantages of these new electrolytes over the currently dominant systems, highlighting their chemical stability, greater ionic mobility, higher conductivity and other favorable chemical characteristics.
Despite the various benefits brought by the FSI anion, there are several questions to be addressed in the research of FSI-based electrolyte:
The article also addresses a variety of challenges for future research, including the development of efficient and environmentally friendly methods to make these electrolytes, and the need for a better understanding of their chemical behavior in real battery applications.
The authors concluded: “The research in FSI ions could also help the work of exploring other alternative electrolytes for the batteries of the future. These developments could be important to expand the technology of lithium batteries in large-scale storage structures in the national electricity supply networks.
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