Design And Simulation Of Novel Two-dimensional Energy Storage Materials Based On Density Functional Theory Calculations

With the continuous advancement of theoretical calculation methods and computing power,designing new materials by theoretical calculation has become an important means to promote the progress of materials science.Since the discovery of graphene in 2004,it has attracted people’s attention because of its unique geometry and excellent physical and chemical properties,and it is expected to play an important role in the field of energy storage.In this thesis,by means of density functional theory calculation,we designed two novel two-dimensional materials and systematically explored their potential applications in the field of metal ion secondary batteries.Ti₂PTe₂ is a layered ternary transition metal chalcogenide synthesized experimentally.According to calculations,We found that Ti₂PTe₂ has a smaller cleavage energy,so Ti₂PTe₂ monolayer is very expected to be experimentally obtained by mechanical exfoliation.Unlike many semiconducting two-dimensional transition metal chalcogenides,the Ti₂PTe₂ monolayer has a distinct electronic state near the Fermi level and exhibits metallic properties.In particular,the two-dimensional Ti₂PTe₂ monolayer can provide a relatively high theoretical capacity(280.75 mAh·g^-1)and a relatively low open circuit voltage（0.31 V）when used as anode material for sodium-ion batteries.Therefore,the two-dimensional Ti₂PTe₂ monolayer is a promising anode material for sodium-ion batteries.We studied the electrical properties and energy storage properties of another two-dimensional layered material Nb₂S₂C through theoretical calculations.The results show that the cleavage energy of Nb₂S₂C is very close to that of graphite,indicating that the Nb₂S₂C monolayer is easily obtained experimentally.We found that Li,Na,K,and Mg have higher adsorption energy and lower diffusion barrier when adsorbed on the Nb₂S₂C monolayer Especially,the Nb₂S₂C monolayer has higher theoretical capacity and lower open circuit voltage for Li,Na,K,and Mg.Thence,the Nb₂S₂C monolayer is an ideal anode material for metal ion secondary batteries and has a broad field in the field of energy storage.