The First Principles Study Of Magnesium Battery Electrode Materials

Magnesium is currently one of the most abundant light metal elements on earth reserves,due to its good physical,chemical and mechanical properties,make it as the hot spot of the research gradually,it has high stiffness and strength,good machinability and casting performance,and in accordance with the subject of present energy recycling.In the automotive industry,automation industry and electronic products it has been widely used,After lithium ion batteries and sodium ion batteries,magnesium ion batteries have been the key research of new energy sources due to its full reserves and more charge numbers,tightly button up the theme of green environmental protection and energy saving in the trend of society,magnesium and magnesium alloys play an extremely important role in its industrial application for energy saving aspects in the world,and more and more attention were paid for the study of magnesium ion batteries,the research are increasingly widespread.In this paper,a method of first-principles calculations was used to study the Mg battery materials and its stability.For the magnesium battery anode material,Mg₃P₂ is the most stable structure for red phosphorus,the second stable structure is Mg₄P₃ and Mg₂ P,and the minimum volume expansion rate of Mg₄P₃ is about 232%,Mg₂ P structure is 304%,both between lithium battery and sodium battery.And the average voltage of atoms embedded is 0.68 V and 0.77 V,close to the average voltage of the intercalated-Li structure0.85 V.Results show that the structure of compounds are similar to layered structure,because black phosphorus are fold layered materials,the channel between the layers is enough big,so we do further research for layered black phosphorus as anode materials.The number of magnesium atom of the most stable site for black phosphorus is four,that is Mg_0.11P_0.89,this structure need to overcome the energy barrier of the diffusion path of the levels of phosphorus is the path between the black layer structure,the value of energy barrier is 2.63 eV.For the electrode material,the stability is a considerable question,the environment of the common elements such as hydrogen,oxygen and nitrogen,and common impact of twinning twins of magnesium.Determining hydrogen,oxygen,nitrogen atom minimum formation energy in twins and the most stable solution position.And we used the first-principles to study the strengths and weaknesses of the red phosphorus and blackphosphorus as the magnesium battery electrode material.For the?10-11???10-12?and?10-13?twins,its most stable position are the high-symmetry solution site or octahedral position near the twin boundaries and on the twin boundary,while for?10-13?twins,a greater impact on the crystal structure after solution embedded atom,lattice distortion.The calculation results of electron localization function and density of states show that all the three kinds of solid solution elements connect with Mg atoms through metallic bonds.Their solid solution will not affect the metal nature of Mg twins.