| Lithium-ion battery is one of the most widely used energy storage batteries.The development of new energy,especially large-scale photovoltaic and wind power,requires higher performance energy storage equipment,which puts forward higher requirements for the performance of lithium-ion batteries.For lithium ion batteries,the electrochemical performance mainly depends on their electrode materials,electrolytes and separators.Compared with electrolyte and separator,the development of battery materials,especially anode materials,is one of the primary concerns of current battery technology.Lithium ion battery anode material as the key material of battery technology iteration needs further breakthrough.Two-dimensional materials represented by graphene have great potential as anode materials for lithium-ion batteries.First,because their fully exposed surfaces are considered to supply fast ion diffusion and maximum ion insertion channels;secondly,two-dimensional materials can be tailored according to dimensions due to their physical and chemical properties,and have good plasticity compared to three-dimensional materials.The recently discovered PC6 monolayer has ultra-high mobility comparable to graphene and a high absorption coefficient(105 cm2)in a wide spectral range,with a direct band gap of 0.84 e V.Based on these superior properties,PC6 monolayer is considered as a potential candidate for battery anode materials.In this paper,the application of PC6 doping in lithium ion battery anode was explored by theoretical simulation.The effect of PC6 doping on the adsorption and diffusion properties of lithium ions was studied,and the reasons for its influence were analyzed.The main research contents are as follows :1.The possibility of P in S-substituted doped PC6 as anode material for lithium ion batteries was studied.The stability of S-doped PC6 was analyzed by formation energy and cohesive energy.After determining its thermal stability,the theoretical capacity of S-doped PC6 as anode of lithium ion battery was 519.77 m A·h/g and the average open circuit voltage was about 0.15 V by first-principles calculation.In addition,in order to study the electrical transport properties of S-doped PC6 as a battery material,the density of states and energy bands were calculated for the former and latter models.The calculation results show that they exhibit metal properties,indicating that the material has good conductivity as a battery anode material.At the same time,the lithium ion migration ability was determined according to the transition state search calculation,and the diffusion barrier of S-doped PC6 monolayer was 0.34 e V.2.The possibility of B and N doped C in PC6 as anode materials for lithium ion batteries was studied.The formation energy and cohesive energy calculations show that B and N are kinetically stable anode materials.Secondly,the theoretical capacities of B and N doped PC6 as lithium ion battery electrode materials are 781.56 m A·h/g and 778.72 m A·h/g,respectively.In order to obtain the lithium ion migration parameters of the doped structure,the diffusion barrier of lithium ion doping several surfaces is calculated.The values of B and N doping are 0.37 e V and 0.33 e V,respectively.In addition,the open circuit voltage of B and N doped anode materials for lithium ion batteries was calculated to be 0.19 V and 0.23 V,respectively.The calculation results show that among these doped structures,B doping has the strongest adsorption of lithium,while S is the weakest,which is related to the change of electronic properties of doped atoms.The B and S doping in PC6 can reduce the diffusion barrier of lithium,among which the N doping diffusion barrier is the lowest and the B doping diffusion barrier is the highest.The theoretical specific capacity of B doping is the highest.The average open circuit voltages of B,N and S doped Li-ion batteries are in a good range(0.1 ~ 1V).It shows that the three doped PC6 monolayers have the potential as anode materials for lithium ion batteries. |
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