Design And Interfacial Stabilization Of Electrolytes For Wide Temperature Domain Aqueous Li-Zn Hybrid Batteries

Aqueous batteries are an important supplementary to the field of large energy storage devices,of which Zinc-based aqueous batteries are a current research trend due to their low cost and high specific capacity.In order to satisfy the requirements of different environments for battery performance,batteries are required to widen the operating temperature.As the electrolyte of the battery contains a large amount of free water,the viscosity of the electrolyte will increase and even freeze at low temperatures,slowing down the interfacial reaction rate.Therefore,controlling the content of free water in the electrolyte is the key point and challenge to solve the problem of interfacial stability of Zn anode and improve the performance of the battery in a wide temperature range.In this paper,we start from the electrolyte design to control the free water content,improve the interfacial stability of Zn anode,decrease the freezing point of electrolyte and improve the overall performance of aqueous battery in wide temperature range.It mainly includes the gel electrolyte with structural water fixing design,the functional additive modified electrolyte with component water reduction perspective design and the high concentration salt electrolyte.The main content of this paper is as follows:Firstly,functional additive is used to modify the low freezing point electrolyte design and interfacial stabilisation.On the one hand,using ethylene glycol（EG）and dimethyl sulfoxide（DMSO）,the electrolyte freezing point（-30°C）was lowered by breaking the hydrogen bonding network between the water molecules.On the other hand,the two molecules reduced the Zn anode corrosion current and enabled the dissolution and deposition of Zn ions in the（002）crystal plane in a selective orientation,inhibiting the growth of Zn dendrites.Assembled Zn-Li Mn₂O₄ full battery with excellent multiplicity and cycling performance at both room and low temperatures.Design of glycerol-enhanced double cross-linked polymer gel electrolytes and interfacial stabilisation research.Acrylamide（PAM）is chosen as the main component of the gel electrolyte and glycerol（Gly）is used as an antifreeze additive.At room temperature,the water retention performance of the electrolyte gradually increased with increasing the proportion of glycerol,and the water retention time was more than 30 days atφ50%.By the strong fixing of water molecules through Gly-PAM double cross-linking,the freezing point ofφ50%Gly electrolyte can reach below-40°C.High flexibility and safety in tough environments（cutting,bending）.Zn symmetrical cells tested at 25°C,500 stable cycles;-20°C,800 stable cycles.Assembled Zn-Li Mn₂O₄ full battery,showing excellent electrochemical performance at 25 to-40°C.Design and interfacial stabilisation research using a high concentration of acetate low freezing point electrolyte.Using the high dissolved and low cost acetate as the electrolyte salt,7 mol.L^-1 CH₃COOLi+1 mol.L^-1 Zn（CH₃COO）₂ freezing point can be below-40°C.However,the viscosity of the electrolyte increases with increasing salt concentration.In order to decrease the liquid viscosity of the electrolyte,0.6 mol Li Cl was introduced into the electrolyte to increase the ionic conductivity at low temperatures.The addition of Li Cl was also tested and found to reduce the deposition potential of Zinc ions at the anode,which can enhance the uniform deposition on the Zinc surface and improve the cycling stability of the battery.At 25°C,the Zn-Li Fe PO₄ full battery is assembled and cycled stably for 600 cycles(1 A.g^-1).At-30°C,0.1 A.g^-1 for 500 cycles capacity retention 88.5%.Effectively resolves the problems of poor low-temperature performance and cycling instability in the industrialisation of Li-Zn hybrid batteries,thus establishing a basis for promoting industrialisation.