Add a catalyst to change the salt concentration of the kinetic rate of lithium battery increased by several times

Science and Technology Daily News (reporter Jin Feng correspondent Zhou Wei Wang Hongzhou) in the current research of the new secondary energy storage system, lithium-oxygen battery is the theoretical battery system with the highest specific energy.However, the insulation of its discharge product lithium peroxide hinders the development process of lithium-oxygen battery.Professor Chen Yuhui of Nanjing University of Technology, together with Professor Shi Siqi and Austrian scientists, found that changing lithium concentration or solvent can increase the electrochemical rate of insulators several times.The research results were recently published in the international authoritative journal Nature Catalysis.

Unlike lithium-ion batteries, such as intercalated batteries, which mainly rely on ion stripping or embedding to balance the redox charges of mixed conductive solids, future battery technologies such as lithium-oxygen batteries and lithium-sulfur batteries will produce insulating substances.Lithium-oxygen batteries convert oxygen dissolved in the electrolyte into a solid-state insulating substance lithium peroxide during discharge or charge.Lithium-sulfur batteries can convert the solid-state insulation material sulfur and lithium sulfide with each other.Charge transfer occurs between electrodes and insulating, insoluble, solid storage materials, causing high overpotential and incomplete conversion even at low magnification.

"We experimentally found that lithium iodide as a catalyst has a mutation potential when reacted with insulating substances such as lithium peroxide."Cao Deqing, the first author of the paper and a doctoral student at Nanjing University of Technology, said that when the vector potential is lower than the mutation potential, the dynamics of the redox medium reaction with the insulating substance is slow, and when the potential is only higher than the mutation potential, the dynamics of the reaction between the redox medium and the insulating substance will suddenly accelerate.The change in the potential of the medium can be adjusted by changing the concentration of lithium salt or changing the solvent.

"After intensive research, we found that this phenomenon exists not only in lithium iodide, but also in other media that react with lithium peroxide, which can be extended to other battery systems besides lithium-oxygen batteries, such as lithium-sulfur batteries."Chen said that they found that the reason for the mutation potential was actually related to the crystal surface of the insulating material.Because insulating substances such as lithium peroxide are polycrystalline surfaces, the potential of the medium should exceed the minimum overpotential required to dominate the crystal surface.

"This research result provides a new idea for the selection of medium for lithium-oxygen and lithium-sulfur battery systems, and provides a new basis for future research on medium catalysts."The research will also promote the industrialization of lithium-oxygen batteries, lithium-sulfur batteries, provide more options to replace the current commercial lithium-ion batteries, and will further accelerate the development of large energy storage systems such as new energy electric vehicles.