不同形貌FeS_(2)的可控制备及储钠特性研究

Controllable synthesis of FeS_(2) with different morphologies and their sodium storage performances

作为典型的转化反应型储钠负极材料,FeS_(2)具有无毒、成本低廉及理论比容量高等优势,成为钠离子电池潜在的负极材料之一。然而,该材料在实际储钠过程中的动力学性能相对较差,限制了其实际应用。基于此,本研究基于溶剂热反应合成策略,通过改变前驱体中铁硫摩尔比,分别合成了具有不规则球形颗粒形貌,球形颗粒与立方体混合形貌以及规则立方体形貌的FeS_(2)样品,进一步分析研究了微观形貌对FeS_(2)储钠性能的影响。电化学测试结果显示,具有规则立方体形貌的FeS_(2)具有最优的倍率性能和循环稳定性,在0.1 A/g的电流密度下循环100次以后可保持354.5 mAh/g的放电比容量,在电流密度为2.0 A/g下循环500次后,仍保持246.3 mAh/g的放电比容量,是对比样品比容量的1.2倍。储钠动力学分析表明,立方体形貌的FeS_(2)样品表现出赝电容占主导的储钠机制,因此具有更快的钠离子扩散效率和更高的倍率性能。该研究能够为高性能转化型钠离子电池负极材料的开发提供理论参考和依据。

As a typical conversion reaction-type anode material for sodium-ion batteries(SIBs),FeS_(2),which possesses the merits of nontoxic,low-cost,and high theoretical specific capacity,has become a potential anode material for SIBs.However,owing to the large atomic radius and mass of Na+,the Na storage process of FeS_(2) features sluggish kinetics,which hinders its practical applications.In this study,we synthesize FeS_(2) with different morphologies through a solvothermal method.The morphology can be easily controlled by changing the molar ratio of Fe and S in the precursor.Characterization results reveal that as-obtained FeS_(2) with different molar ratios of Fe and S presents an irregular spherical particle and a mixture of an irregular spherical particle and regular cubes.Furthermore,the Na storage performances of as-obtained samples were systematically investigated.FeS_(2) with a regular cubic morphology reveals a superior Na storage performance.A reversible discharge specific capacity of 354.5 mAh/g can be maintained at a current density of 0.1 A/g.Long-term cyclic tests reveal that after 500 cycles,a discharge specific capacity of 246.3 mAh/g can be obtained,which is 1.2 times higher than that of the control sample.A Na storage mechanism analysis indicates that FeS_(2) with a regular cube morphology presents a capacitive-dominated Na storage process,which promotes an enhanced rate capability and fast Na+diffusion coefficient.This study can provide theoretical reference for fabricating high-performance anode materials for SIBs.