Key Materials And Working Mechanism Investigation For Novel High Efficiency And Low Cost Energy Storage Devices

The prominence of energy and environmental problems makes people pay more attentions to the utilize and development of clean energy.Efficient energy storage system plays a key role to achieve this goal.At present,lithium-ion batteries(LIBs)have become the dominant rechargeable energy storage devices.However,uneven geographical distribution as well as limited lithium resources are reflected in a rapid rise of price,thus hindering wide applications of LIBs in the field of large-scale energy storage systems.Therefore,in the post-lithium era,the development of other ion energy storage technologies has received increasing attention from researchers.However,these new developing technologies requires technological accumulation,and there are still many problems in the key materials.Therefore,the development of new energy storage materials with excellent performance is a necessary way to solve these problems.In recent years,first-principles calculations based on density functional theory have played a key role in the design and development of materials.Therefore,in this paper,we have used the first-principles calculation based on density functional theory as a powerful means to design key materials and optimize energy storage technology from three aspects of electrode materials,catalyst and electrolyte-electrode interface.The developed materials are applied to the corresponding energy storage devices,and their mechanisms are further studied.This paper provides some solutions to the challenges existing in the alternative energy storage system in the post-lithium era,and plays a certain role in promoting the alternative energy storage devices with high efficiency and low cost as well as diversification of application scenarios.1.To overcome the problem of large ion reversible storage for energy storage system,in the first research part of this paper,by means of first-principles calculation based on density functional theory,through theoretical simulation,the material potassium fluoride oxalate(KFe C2O4F)was constructed with oxalate as polyanion plane basic skeleton,fluoride as three-dimensional extended skeleton,transition metal iron as material redox center,and alkali metal potassium ion as charge carriers.The material has an open rigid skeleton structure,in which the large size and planar structure of oxalate may bring larger ion diffusion channels for the potassium storage frame,and fluoride ions further increase the pore size and the rigidity and stability of the skeleton.In addition,the cell shrinkage/expansion rate and the corresponding volume change rate during potassium ion extraction/insertion are small,and the oxalate which constitutes the material skeleton is not easy to decompose in the reaction process.The half-cell and fullcell reveal good rate performance,cycle stability and power density.This work provides a good idea for guiding the design of reversible storage electrode materials for large ions in new energy devices.2.In order to solve the problem of high price of platinum-based catalysts using in electrocatalytic oxygen reduction reaction,the second research part of this paper will use first-principles calculation based on density functional theory as a tool to develop non-noble metal single-atom catalysts with high activity through reasonable coordination design.It is divided into two main contents:(1)Based on the bionic design of enzyme guided by DFT,it was proposed for the first time that semi-metallic Te clusters were used as coordination regulators.Through the adaptive adjustment behavior of tellurium clusters and the bonding dynamics between Fe 3d and Te 5p orbitals,each electron transfer step in the ORR process was promoted to regulate the ORR process of single-atom catalysts.On this basis,a FeN4-Ten electrocatalyst with stable activity,which simulates biological enzyme but maintains the stability of heterogeneous catalyst,was designed reasonably,and its excellent electrocatalytic ORR performance was confirmed.(2)Based on the guidance of DFT,a new theoretical model of large-sized yttrium single-atom catalyst was proposed.On this basis,the regulatory effects of different groups on the ORR process of large-sized yttrium single-atom catalyst were revealed,and the better regulatory groups were selected as well as a new screening criterion was proposed.We revealed the adaptive adjustment behavior of axially coordinated chlorine atoms and the general promotion of the ORR process by the bonding dynamics between Y 4d and Cl 3p orbitals,and the good electrocatalytic ORR activity of YN4-Cl catalyst was also verified by experiments.3.In order to solve the problems of dendrite growth and hydrogen evolution reaction in zinc ion batteries,the third research part of this paper will used first-principles calculation based on density functional theory as a tool and build an inorganicorganic protective layer on the surface of zinc foil through reasonable electrolyte control(electrolyte additive design).The results show that some compounds containing organic and inorganic groups(such as potassium vinyltrifluoroborate and Adenosine 5'-triphosphate disodium salt)can spontaneously form inorganic-organic protective layer during the electrochemical process.The inorganic layer uniformly covers the surface of zinc,promoting the uniform deposition of zinc and reducing the dendrite growth.The organic layer grafted on the inorganic layer can promote the formation of high concentration electrolyte at the interface and reduce the hydrogen evolution reaction at the interface effectively.In addition,the uniform diffusion channels in the inorganic-organic layer further induced the uniform deposition of zinc ions.This work provides a solution for theoretically guiding the design of inorganic-organic layer on metal surface to inhibit dendrite growth and hydrogen evolution reaction.