Fluorine-free electrolytes in batteries: principles, strategies, and advances

Abstract

Electrolytes play a pivotal role in battery technologies, influencing performance and safety. However, electrolytes containing fluorine present adverse environmental risks due to their high greenhouse gas emissions, which contribute to global warming. Hence, developing fluorine-free alternatives is imperative to design net-zero fluorine electrolytes. This review addresses the need for sustainable, low-toxicity electrolytes by exploring strategies for eliminating fluorine in the electrolyte system. Studies on the choice of electrolyte ingredients, such as fluorine-free salts, green solvents, safe additives, and fluorine-free binders, have demonstrated that specific electrolyte ingredients can effectively enhance battery performance and safety. Recent progress highlights significant improvements in the environmental impact and functionality of fluorine-free electrolytes (FFEs), demonstrating their potential for practical applications. Despite these advancements, challenges remain in matching the performance and stability of traditional fluorinated electrolytes. Future research encourages us to focus on developing fluorine-free materials, understanding functional degradation processes, and ensuring commercial scalability. This review provides an in-depth look at recent innovations and promotes design principles for complete fluorine elimination strategies. It guides future pathways for creating high-performance, non-flammable, low-cost, environmentally sustainable FFEs for advanced rechargeable batteries. The summary and perspectives emphasize the importance and future directions of a sustainable circular economy in advancing sustainable electrolyte engineering.