Research On The Design And Performance Of Cathode Materials For Lithium-oxygen Batteries

In recent years,the energy market has continued to develop,and new energy vehicles,mainly represented by traditional lithium-ion electric cars,have quickly entered the vision of the automotive transportation market and gained a place.However,lithium-ion batteries with limited energy density cannot achieve convergence with the rapidly growing standard fair for the electric vehicle industry.Therefore,we are waiting to develop a new generation of an energy storage system with high specific energy density to replace the traditional lithium-ion batteries.The study has found that lithium-oxygen battery has ultra-high theoretical specific capacity(3860 m Ah g^-1)and high specific energy(11425 Wh kg^-1).Currently,the lithium-oxygen battery still has some way to go before it can be mass-promoted in the market.Because of its large charge and discharge overpotential,which results in unsatisfactory cycling and rate performance.The development of catalyst material with high catalytic performance is significant to improve the electrochemical performance of the lithium-oxygen battery.In this work,a bimetallic hydroxide catalyst was prepared by the hydrothermal method,and the physical characterization test of its morphology and structure is carried out with the help of advanced physical characterization technology.In the process of experiment,metal nitrates were used as the main raw materials,and different Ni Co-LDH material was synthesized by changing the molar ratio of metal nitrates.The results indicate that when the molar ratio of the elements of nickel and cobalt is 1:3,the prepared Ni₁Co₃-LDH catalyst material shows excellent electrochemical performance in the electrochemical test of the lithium-oxygen battery.When the current density is 100 m A g^-1,the battery's first discharge specific capacity reached 4200 m Ah g^-1,and the charge specific capacity also reached to 3997 m Ah g^-1.Coulomb efficiency is about 95.2%.When the tested current density sequentially increased to 150 m A g^-1,200 m A g^-1,300 m A g^-1,the specific discharge capacity of the electrode was 2721 m Ah g^-1,1936 m Ah g^-1,and 1555 m Ah g^-1,respectively.Under the controlled capacity of 300 m Ah g^-1,the battery can be stably charged and discharged for 31 cycles.The experimental results indicate that the Ni Co-LDH catalyst has sound oxygen reduction and oxygen evolution catalytic activity,and reduce the overpotential during the charge and discharge process.Then another work also tried to dope the strontium metal into the porous coordination polymer?metal-organic framework?to synthesize a new catalyst material,namely Sr-ZIF-8.Different Sr-ZIF-8 material was prepared by changing the molar ratio of metallic strontium and metallic zinc.The prepared Sr-ZIF-821 material was used in the lithium-oxygen battery,and its electrochemical performance was investigated.Under the test condition of the current density of 100 m A g^-1,the first discharge specific capacity of the electrode was measured to be 4048 m Ah g^-1.Under the controlled test condition with the specific capacity of 300 m Ah g^-1 and current density of 100 m A g^-1,the battery can run for 27 times.The experimental results show that the Sr-ZIF-821 electrode exhibits good oxygen reduction and oxygen evolution catalytic function in the lithium-oxygen battery.At the same time,it also proves the application ability of ZIF-based crystal material in the electrocatalytic direction of the lithium-oxygen battery.This work will provide a new research idea for the future research of metal-oxygen battery catalyst material.