| Metal-air batteries have the advantages of high specific energy,low cost,and environmental protection,and are a popular technology for a new generation of energy storage batteries.However,the current research on metal-air batteries,due to the corrosion of the metal negative electrode,the self-discharge of hydrogen evolution,and the slow kinetics of the oxygen reaction of the air positive electrode,affect the coulombic efficiency and cycle life of the battery,resulting in its failure to be promoted and applied on a large scale.This paper designs and constructs a new type of copper-air molten salt secondary battery.The electrolyte uses potassium hydroxide and sodium hydroxide eutectic molten salt,which has the advantages of large electrochemical window,high ion conductivity,and rapid electrode reaction.The negative electrode uses metal copper that is excellent in conductivity,thermodynamically stable,safe and environmentally friendly,and easy to recycle,which can effectively avoid electrode corrosion,hydrogen evolution side reactions and the generation of metal dendrites.The positive electrode uses a nickel-based multilayer gas diffusion electrode,which has good corrosion resistance and high temperature resistance,and can circulate stably in molten salt.In addition,the production of metallic nickel is abundant and the cost is low,and no precious metal catalyst is required,which can greatly reduce the cost of the metal-air battery.On this basis,this article first studied the battery reaction mechanism of the copper-air molten salt battery,confirmed that the discharge reaction was carried out in two steps,and the products were cuprous oxide and copper oxide,and deduced the reaction equation of the battery.Then,according to the huge entropy change caused by the participation of oxygen in the battery reaction,the temperature characteristics of the battery were studied,and the temperature coefficients of the two-step reaction of the battery were deduced to be-0.39 m V K-1 and-0.53 m V K-1,which are better than Traditional thermoelectric conversion materials.Use this temperature characteristic to determine the best operating temperature of the battery as 180℃,and study its application to recover low-level heat to reduce the energy consumption of battery charging.Next,different metal oxides Ni O and Ni-Fe MMO were loaded on the nickel-based air cathode,and the composition,morphology and structure were characterized,and the ORR/OER catalytic activity of the electrode and the battery charge were tested.The influence of discharge performance and cycle performance.Among them,the copper-air molten salt battery loaded with Ni O is charged to 1 m Ah with a constant current of 10 m A and discharged to 0.4 V,can be cycled stably for 400 cycles,and the average coulombic efficiency of the battery is above 90%.The load Ni-Fe MMO can cycle 600 cycles stably under the same conditions,and the average coulombic efficiency of the battery exceeds 99%.Studies have shown that the large surface area of Ni-Fe MMO and the mixed valence state of iron can provide excellent ORR/OER catalytic activity,and show good stability in high-temperature molten salt.It is a very potential air cathode catalyst.Finally,the stability of the copper anode,the failure mechanism of the electrolyte and the regeneration performance of the battery are also studied.The copper-air molten salt secondary battery proposed in this paper is a brand-new metal-air battery technology.It has the advantages of good cycle performance,low production cost,easy assembly,high safety performance,and convenient recycling.It is expected to be popularized and applied to large-scale storage.Energy and low-grade heat energy recovery field. |
PDF Full Text Request