单层Si_(3)N作为钠/钾离子电池的高容量阳极材料的可行性研究

Monolayer Si_(3)N as a high-capacity anode material for ultrafast charging Na/K-ion batteries

采用密度泛函理论(DFT)研究了二维单层Si_(3)N作为离子电池阳极材料的相关性能.零带隙能带结构表明,单层Si_(3)N具有金属特性,金属的高导电能力有利于其作为阳极材料.计算结果表明,单层Si_(3)N对于钠和钾的理论容量分别为1230 mAh∙g^(-1)和889 mAh∙g^(-1).与此同时,该材料对钠和钾的理论能量密度分别为1090 mWh∙g^(-1)和576 mWh∙g^(-1),高于之前一些报道的二维阳极材料.此外,钠、钾原子在单层Si_(3)N上的扩散势垒分别为0.30,0.38 eV,表明该材料具有非常高的充放电速率,且在吸附过程中,Si_(3)N一直保持着良好的金属特性和结构完整性,这些性质使其具有良好的电池工作循环性能.以上结果表明,单层Si_(3)N是理想的钠/钾离子电池阳极材料.

In this work,we have studied 2D monolayer Si_(3)N using density functional theory(DFT).The zero gap band structure shows that the Si_(3)N is of metal properties,which is favorable for anode material.The high specific capacity of Na and K is expected to be 1230 mAh∙g^(-1) and 889 mAh∙g^(-1),respectively.Meanwhile,the theoretical energy densities of Na and K are 1090 mWh∙g^(-1) and 576 mWh∙g^(-1),respectively,which are much higher than some previously reported 2D material anodes.In addition,the predicted diffusion barrier for adsorption of Na,K ions is 0.30,0.38 eV,which indicates that this material has a very high rate capacity.In the process of Na/K ion intercalation,the metallic characteristics and structural integrity of Si_(3)N are maintained,which makes it have good working cycle and conductive performance of the battery.These results indicate that Si_(3)N can be used as an ideal anode material for sodium and Na/K-ion.