Chemists and engineers have been working to develop more efficient, inexpensive, and reliable battery technology to power a variety of electronic gadgets. To do this, scientists have been using the multi-redox reactions of elements that are plentiful on Earth, like as iron and manganese, which might assist to reduce battery production costs.
A team of researchers at Seoul National University discovered amorphous iron fluorisulfate electrode a-LiFeSO4F, which might be utilised to produce more economical high-capacity batteries. This electrode, described in a Nature Energy publication, particularly functions as a cathode (i.e., the positively charged electrode in a battery cell, through which electrons enter electronic devices).
They were motivated to construct the iron fluorisulfate cathode by a nanocomposite material that they had presented in one of their prior publications, where they also revealed its underlying redox mechanism and surface conversion reaction. This substance is made up of nanosized lithium and a transition metal complex.
“Previously, we were researching techniques for generating more capabilities from our nanocomposite cathode material,” said Kisuk Kang, one of the study’s authors. “Because the material’s redox mechanism is analogous to a conversion reaction and is normally synthesised by high energy ball milling, we were able to get a better knowledge of the conversion reaction and mechanochemical synthesis.”
The team’s current study is based on their prior research’s observations and conclusions. Their previous discoveries encouraged them to investigate the prospect that the conversion reaction of their nanocomposite cathode material, paired with an intercalation capability, might enable them to access the unique capacity of the transition metal oxides inside it.
“We pondered how to effectively boost the reversibility of an intercalation/conversion dual-type electrode material throughout the creation of this idea,” Kang added. “Considering the nature of the conversion process, we concluded that an amorphous structure may aid in this.”
Kang and his colleagues created a cathode out of LiFeSO4F with an amorphous (i.e., non-crystalline) structure. This material is readily produced using mechanochemical techniques, especially high-energy ball milling of lithium fluoride (LiF) and iron sulphate (FeSO4). The researchers’ cathode has a significant advantage in that it allows for the reversible insertion and extraction of lithium ions through two processes known as intercalation and conversion. This considerably improves its cumulative capacity, which may enhance the life and performance of a battery.
“Our research revealed a unique function for amorphous structure in allowing reversibility of dual-type intercalation/conversion electrode material,” Kang added. “The reversible and simultaneous use of intercalation and conversion processes in the amorphous structure is generally applicable to different transition metal compounds, therefore expanding the candidate group of high-energy density cathode material.”
The cathode developed by this team of academics might be utilised to develop high-capacity, low-cost battery technologies in the future. Furthermore, its underlying chemical processes might be recreated using various transition metal compounds, opening up new avenues for the development of high-performance cathodes based on Earth-abundant materials.
“Since we validated our notion, we’ve started investigating a larger compositional space to uncover additional viable cathode materials,” Kang said. “We are also investigating the overall governing laws guiding the synthesis of amorphous structure, as well as the connections between amorphization and intercalation capabilities.”
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