High power amorphous ferric fluorosulfate cathode

Chemists and engineers have been trying to create increasingly efficient, affordable, and stable battery technologies to power a wide variety of electronic devices. To do this, they took advantage of the multi-redox reactions of materials abundant on Earth, such as iron and manganese, which could help reduce the cost of making batteries.

A team of researchers at Seoul National University have identified a-LiFeSO₄F, an amorphous ferric fluori- sulphate electrode could be used to develop more affordable high-capacity batteries. This electrode, presented in a paper in natural energyspecifically acts as a cathode (that is, a positively charged electrode in a battery, through which electrons enter electronic devices).

The iron fluorisulfate cathode they created was inspired by a nanocomposite material they introduced in one of their earlier works, where they also elucidated its underlying redox surface and mechanism. . convert the reaction. The material consists of nanoscale lithium and a transition metal compound.

Kisuk Kang, one of the researchers who carried out the study, told TechXplore: “Previously, we were working on strategies to obtain additional energy from our nanocomposite cathode materials. “Since the redox mechanism of the material is similar to the conversion reaction and is often synthesized by high-energy ball mills, we can better understand the conversion reaction and mechanosynthesis.”

The team’s new study builds on observations and findings gathered in their previous research. In particular, their previous findings inspired them to explore the switching reactivity of their nanocomposite cathode materials, which, combined with intercalation capabilities, would allow them to unlock a unique ability of the transition metal oxides within it.

“During the development of this concept, we thought about how to effectively enhance the reversibility of the alternating/switched dual-type electrode materials,” explains Kang. “We came to the conclusion that an amorphous structure could help achieve this, considering the nature of the conversion reaction.”

The cathode recognized by Kang and colleagues is made of LiFeSO₄F, but has an amorphous (i.e., non-crystalline) structure. The material can be easily synthesized by mechano-mechanical processes, namely through high-energy ball milling of lithium fluoride (LiF) and ferrous sulfate (FeSO).₄).

One notable advantage of the researchers’ cathode is that it supports reversible lithium ion insertion and separation through two processes known as intercalation and conversion. This greatly increases its accumulated capacity, which in turn can improve battery life and performance.

“Our study has revealed a novel role of the amorphous structure in enabling the reversibility of dual-type switching/intercalation electrode materials,” said Kang. “The reversible and simultaneous use of intercalation and transition reactions in the amorphous structure is widely applicable to other transition metal compounds and thus broadens the candidate pool of cathode materials. high energy density.”

In the future, the cathode introduced by this group of researchers could be used to create low-cost and high-capacity battery technologies. In addition, its basic chemical processes can also be reproduced using other transition metal will open up new possibilities for creating high-performance cathode based on Earth-abundant materials.

“Since we verified our concept, we have explored a more open compositional space to identify other possible possibilities. negative materials,” added Kang. “Furthermore, we are studying the general governing rules related to the synthesis of amorphous structures and the correlation between the amorphous and intercalated capacities. .”

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