Electrochemical Fluoridation of Manganese Oxide by Perfluorinated‐Gas Conversion for Lithium‐Ion Cathodes

Abstract

Fluoridation of Lithium-ion (Li-ion) cathodes is of growing interest for high-capacity Li + storage materials, but wellcontrolled fluoridation processes are elusive. We investigated an electrochemical methodology to grow lithium fluoride (LiF) by reduction of perfluorinated gas onto metal oxides (MO), which then forms MÀ OÀ F by splitting of LiF upon charge, using MnO as an example target phase. Unlike current methods where particle size < 10 nm is necessary for high MnO utilization (subsequent discharge/lithiation capacity), owing to the nano-crystallinity and intimate contact of electrochemicallygrown LiF, high MnO utilization (~0.9 e À /MnO, 340 mAh g MnO À 1 ) is achieved with large MnO particle size (~400 nm), exceeding comparable MnO/LiF systems reported to date. Additionally, incorporation of perfluorinated-gas additive benefits cycling, with capacity of ~270 mAh g MnO À 1 retained after 20 cycles. This work demonstrates the opportunity for electrochemically driven fluoridation to achieve high capacities with larger particle sizes needed to bring oxyfluorides closer to practical reality.

Electrochemical Synthesis of Glycosyl Fluorides Using Sulfur(VI) Hexafluoride as the Fluorinating Agent

“…These limitations prompted us to search for the alternative new methods to achieve SF 6 activation. This manuscript describes electrochemical deoxyfluorination with SF 6 that leads to the fast, efficient and scalable formation of glycosyl fluorides . The use of a zinc sacrificial anode provides an effective means to scavenge sulfur and fluoride waste to form benign Zn­(II) sulfides and fluorides, and this protocol holds promise as an inexpensive, safe, and mild method for the utilization of SF 6 for the fluorination of organic molecules.…”