Hydride Ion Intercalation And Conduction In The Electride Sr₃CrN₃

As the world pays more attention to carbon emission restrictions,the demand for clean and renewable energy is becoming more and more obvious.Hydride ions have small ionic radius,large electronic polarizability and a high standard redox potential,which makes them show great application potential in a new generation of electrochem-ical energy storage systems.However,traditional materials with high ionic conductivity to hydride ions are only realized at relatively high temperatures,which greatly limits the development and use of hydrogen energy.As a new type of functional materials,electrides have been reported that the anionic electrons of them can show effectively interact with external hydrogen,leading to excellent hydride absorption and desorption properties.The newly electride Sr₃Cr N₃ has a one-dimensional channel of electron den-sity,which is a rare feature that offers great potential for fast ion conduction.Based on the first-principles Density functional theory and the CI-NEB method in Transition state theory,we studied the hydrogen storage properties and hydride conduc-tion capacity of the Sr₃Cr N₃,and further analyzed the interaction between anion elec-trons and hydride ions in the material.We obtained the amount of hydride ions interca-lation in the host material corresponding to the formation of the most stable hydride phase under standard conditions.And the results show that hydride ions can migrate in the one-dimensional channel of Sr₃Cr N₃,and the migration path of hydride ions in the material has been preliminarily determined.The diffusion coefficient of hydride ions in the material is about 5.37×10^-8 cm²/s.And the migration barrier of hydride ions is as low as 0.30 e V,which is lower than those reported for the best hydride conductors to date.What’s more,the electronic structure of Sr₃Cr N₃ changes from a metal to a wide-gap semiconductor after the hydride ions have been inserted to form Sr₃Cr N₃H.This indicates that the anionic electrons may be the origin of the favorable ion conducting properties.In this work,our results highlight the potential offered by 1D electride for ion-transport applications such as energy storage or gas separation.A wide band gap is also a requisite for electrolyte components in a fuel cell device.This can further expand the application of electrides in new electrical energy storage materials.