Cu–Pb Nanocomposite Cathode Material toward Room-Temperature Cycling for All-Solid-State Fluoride-Ion Batteries

Abstract

All-solid-state fluoride-ion batteries (FIBs) are regarded as attractive alternatives to traditional energy storage systems because of their high energy density; however, they are not applicable at room temperature owing to sluggish ion transport in both the electrolyte and electrode. In this study, a rational design of a Cu–Pb nanocomposite is reported, which was tested as a room-temperature cathode material for all-solid-state FIBs. Following electrochemical pretreatment, self-generated PbF2 could act as a fast fluoride-ion conductor and consequently enhance the kinetics of the Cu/CuF2 phase transition process upon cycling. The detailed reaction mechanism and phase transition process were verified using the X-ray absorption near edge structure. The Cu–Pb nanocomposite could realize reversible (de)­fluorination at room temperature with high performance and good cyclability.

Evidence of a reversible redox reaction in a liquid-electrolyte-type fluoride-ion battery

“…As reported previously, 7–26 the rechargeable Q values for liquid-electrolyte-type FIBs are somewhat lower than those for all-solid-state FIBs. In this study, Q cha at the first cycle was only ∼9 mA h g −1 when the discharge cut-off voltage was set to 0.1 V [Fig.…”

Anion Substitution at Apical Sites of Ruddlesden–Popper-type Cathodes toward High Power Density for All-Solid-State Fluoride-Ion Batteries

“…Sr 2 MnO 3 F 2 gave a capacity of 84 mAh g –1 with plateaus at 0.2 and −0.2 V during the discharging process and a capacity of 83 mAh g –1 with plateaus at −0.2 and 0.3 V during the charging process (Figure b). Although the cyclability of Sr 2 MnO 3 F 2 was worse than that of LaSrMnO 4 F (Supporting Figure 4b), it was significantly better than those of the conversion-type electrodes. ,,, Comparing the capacity retention at various current densities of LaSrMnO 4 F and Sr 2 MnO 3 F 2 , Sr 2 MnO 3 F 2 showed better capacity retention at high current densities to LaSrMnO 4 F (Figure c).…”

“…Although the cyclability of Sr 2 MnO 3 F 2 was worse than that of LaSrMnO 4 F (Supporting Figure 4b), it was significantly better than those of the conversion-type electrodes. 1,9,32,33 Comparing the capacity retention at various current densities of LaSrMnO 4 F and Sr 2 MnO 3 F 2 , Sr 2 MnO 3 F 2 showed better capacity retention at high current densities to LaSrMnO 4 F (Figure 2c).…”

The case for fluoride-ion batteries

“…Several recent studies on all-solid-state FIBs have demonstrated improved performance in Cu cathodes by tailoring electrode chemistry (using a copper-gold alloy, Cu 3 Au) and electrode composition (via formation of a Cu/PbF 2 composite). 47,48 In both cases improved capacity retention was demonstrated up to 20 cycles. The addition of ionically conductive PbF 2 further enabled cycling at the full theoretically capacity at room temperature.…”