High-Efficiency Zinc-Metal Anode Enabled by Liquefied Gas Electrolytes

Abstract

The practical applications of rechargeable zinc metal batteries are prevented by poor Zn reversibility, which induces both inferior Coulombic efficiency (CE) and zinc dendrite growth that worsens at low temperatures because of deteriorated kinetics in both charge and mass transfer. Herein, a liquefied gas electrolyte based on a mixture of fluoromethane and difluoromethane is demonstrated, which displays an excellent conductivity (>3.4 mS cm–1) across a broad temperature range (−60 to +20 °C) and enables highly reversible Zn cycling with no evidence of shorting behavior at both room temperature and −20 °C for over 200 cycles (>400 h) with an average CE of >99.3% and 20% Zn utilization per cycle. Density functional theory calculations showed that such improvements benefited from a ZnF2-enriched interphase formed on the anode because of decomposition of the liquefied gas electrolyte. This electrolyte was verified in a Zn||Na2V6O16·1.63H2O cell with stable performance, where a similar ZnF2-rich interphase was also confirmed.

Regulating Zn(002) Deposition toward Long Cycle Life for Zn Metal Batteries

“…As is known, modifying an electrolyte with organic solvents is an effective way to decrease the freezing point of electrolyte and enable the cell to operate normally at low temperatures. 41,42 The freezing point of HP20 electrolyte decreases to −20.44 °C as determined from the DSC results (Figure S11). A polyaniline (PANI) cathode was prepared to evaluate the electrochemical performance at −20 °C.…”

“…The HP-based cell also exhibits better rate performance with a much higher discharge capacity than the BE-based cell when the current density increases from 0.2 to 10 A g –1 (Figure b), indicating that the reshaped Zn 2+ solvation structure and planar Zn deposition can stabilize the Zn anode and decrease the side reactions at the electrode interface. As is known, modifying an electrolyte with organic solvents is an effective way to decrease the freezing point of electrolyte and enable the cell to operate normally at low temperatures. , The freezing point of HP20 electrolyte decreases to −20.44 °C as determined from the DSC results (Figure S11). A polyaniline (PANI) cathode was prepared to evaluate the electrochemical performance at −20 °C.…”

Targeted Delivery of Zinc Ion Derived by Pseudopolyrotaxane Gel Polymer Electrolyte for Long-Life Zn Anode

“…On account of the intrinsic properties, rechargeable aqueous zinc ion battery (ZIB) is considered as the promising candidate for the stationary energy storage system. − Zn metal can serve as the anode of ZIB in aqueous electrolyte due to its high theoretical capacity of 5833 mAh cm –2 , the tolerance of water and oxygen, the low potential (−0.76 V vs standard hydrogen electrode), as well as environmental friendliness. − Recently, decent electrochemical performance of cathode has been achieved in ZIBs. − The reaction mechanisms of the cathodes such as the manganese-based compounds, vanadium-based compounds, Prussian blue analogues, and organic compounds have been also investigated, which advance the development of ZIBs. − However, the Zn anode is prone to suffer from the issue of Zn dendrite, which is originated from the uneven Zn plating. − As illustrated in Figure a, owing to the limited Zn 2+ transport, large amounts of zinc ion accumulate at the anode/electrolyte interface . Zinc ion is apt to plate on the location of the Zn anode which presents the minimized surface energy in aqueous electrolyte.…”

Liquid-Phase Speed of Sound and Vapor-Phase Density of Difluoromethane

“…Furthermore, difluoromethane is a component in numerous low-GWP refrigerant blends; it appears in a total of 56 refrigerant blends classified in ASHRAE Standard 34, including a majority of the low- and moderate-GWP blends introduced in the last 5 years. In addition to its use in the refrigeration industry, difluoromethane is actively being investigated by the energy storage industry as a liquified-gas electrolyte material in batteries. − …”