Issue 9, 2024

Dual strategies of mild C–F scissoring fluorination and local high-concentration electrolyte to enable reversible Li–Fe–F conversion batteries

Abstract

Batteries taking conversion-type iron fluorides as energy-dense cathodes provide the possibility for the power electrification of the transportation and aviation industries. However, a safe and low-toxicity synthesis method for fluorides and the design of a compatible electrolyte formula are still challenging. Here, we propose a dual strategy of mild C–F scissoring fluorination and a local high-concentration electrolyte (LHCE) to enable highly reversible Li–Fe–F conversion batteries. A facile and safe scissoring strategy at a low temperature (95 °C) enables the preparation of a carbon–iron fluoride composite with a porous cubic cage-like structure. CFx plays a double role as a solid fluorination agent and an in situ conductive network after defluorination. The as-prepared fluoride cathode delivers a reversible capacity as high as 300 mA h g−1 over 100 cycles. The further LHCE strategy not only enhances the oxidation stable voltage of the electrolyte (>5 V) and the transference number of Li+ (0.74), but also realizes dual protection of the fluoride cathode and Li metal anode by facilitating the construction of robust cathode– and anode–electrolyte interfaces, respectively. The LHCE-assisted fluoride battery releases a higher reversible capacity of 335 mA h g−1 after 130 cycles. This work provides a solution to high-performance carbon–fluoride conversion cathodes by a synergetic effect of tailored synthesis, electroactive particle texture and electrolyte formula.

Graphical abstract: Dual strategies of mild C–F scissoring fluorination and local high-concentration electrolyte to enable reversible Li–Fe–F conversion batteries

Supplementary files

Article information

Article type
Communication
Submitted
13 Nov. 2023
Accepted
02 Febr. 2024
First published
06 Febr. 2024

Mater. Horiz., 2024,11, 2169-2179

Dual strategies of mild C–F scissoring fluorination and local high-concentration electrolyte to enable reversible Li–Fe–F conversion batteries

Y. Yu, C. Lai, M. Lei, K. Chen and C. Li, Mater. Horiz., 2024, 11, 2169 DOI: 10.1039/D3MH01908J

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