Study On Supercapacitor Energy Storage Properties Of Two-Dimensional Electrode Materials:Graphyne,Borophene

Due to the uneven distribution of energy in China,the shortage of reserves and the worsening of environmental pollution,the development of new and green energy conversion and storage devices has become a top priority.Double layer supercapacitors(EDLCs)have attracted widespread attention due to their high output power,long service life,safety and efficiency,but their energy density is low.Designing/developing high-performance electrode materials has become one of the important ways to solve this problem.In a double layer supercapacitor,the total interface capacitance(C_T)can be expressed as:1/C_T=1/C_D+1/C_Q.The total interface capacitance is influenced by the quantum capacitance(C_Q)and double layer capacitance(C_D),but C_Q is at a disadvantage.The first step to increase the total interface capacitance is to increase the quantum capacitance.In this paper,we optimize the structure of three typical two-dimensional materials by introducing vacancy defects,adsorption and doping,modulate their electronic structure,improve their quantum capacitance,and thus improve their supercapacitor energy storage properties.The main work of this paper is as follows:1.The effects of doping B(N,P,S)atoms and adsorbing Au(Ag,Cu,Ti,Al)atoms on the C_Q of graphdiyne(GDY)materials were studied.The results show that doping with B and N increases the C_Q of GDY near the positive and negative potentials,respectively.The maximum capacitance values of P/S doping are 83.2μF/cm~2 and 375.9μF/cm~2.After adsorption of Cu atoms,the C_Q of GDY is significantly improved,with a capacitance value of 316.7μF/cm~2,metal atoms can effectively modulate their electronic structure,thereby enhancing C_Q.The modulated GDY is a potential positive and negative electrode material for supercapacitors.2.The effects of defects,B(N)doping,and the adsorption of transition metal atoms Ag(Au,Cu,Ti,Mn)on the electronic structure and C_Q of graphyne(GY)have been systematically studied.The results show that doping N at different positions improves the C_Q at different negative potentials.For different atomic adsorption systems of GY,the center of the triangular ring is the most stable among the seven adsorption sites.The GY increases with the increase of N doping concentration.The adsorption of Ti atoms increases the C_Q of GY at a positive potential(66.1μF/cm~2),the increase in C_Q is due to the introduction of electronic localized states near the Fermi level.3.Construct a single and double vacancy borophene structure doped with non-metallic atoms C(N,O,P,S)and adsorbed metal atoms Ag(Au,Cu,Ti,Al),and explore the C_Q of borophene.A model of borophene doped with S(N)and adsorbed by Al atoms was constructed.The results showed that S and N doping enhanced the charge accumulation of borophene at positive and negative potential,respectively.The maximum C_Q after S doping is 157.3μF/cm~2(0.38 V).After N doping,the C_Q increases with increasing concentration,with a maximum value of 187.8μF/cm~2(-0.24 V),both of which can be ideal candidates for the positive and negative electrodes of supercapacitors.For the system where metal atoms adsorb borophene,the influence of Al atoms on their C_Q is significant,with a maximum value of 109.1μF/cm~2.