静电纺丝制备内嵌FeF_(2)纳米颗粒导电碳纤维复合材料及其锂离子电池正极性能研究

Preparation and performance study of conductive carbon fibers embedded with FeF_(2)nanoparticles by electrospinning as cathode materials for Li-ion batteries

转换型正极材料(FeF_(2))因高具有理论比容量、廉价与环境友好等优点而有望成为新一代锂离子电池正极材料,但其目前却受到本征导电性差、界面副反应与结构衰减等问题的严重制约。对此,本文利用静电纺丝技术将水溶性高分子聚合物负载金属氟化物前驱体,经预氧化和碳化处理后得到了内嵌FeF2纳米颗粒的导电碳纤维复合材料(FeF_(2)@NFP),并探究了针对FeF_(2)@NFP静电纺丝工艺的最佳碳化温度。在充/放电过程中,FeF_(2)@NFP的碳基质可以发挥限域作用来抑制转换反应造成的体积变化和相分离等问题,从而稳定活性物质的结构,同时导电碳纤维可以为电子传输提供“快速通道”来改善FeF_(2)的导电性。因此,FeF_(2)@NFP作为锂离子电池正极材料在0.1 A·g^(-1)电流密度下表现出了261.55 mAh·g^(-1)的首次可逆比容量以及优异的循环稳定性,在100个循环后仍有243.20 mAh·g^(-1)的剩余可逆比容量(容量保持率为92.98%).

FeF_(2)has the potential to be a game-changing cathode material for lithium-ion batteries due to its high theoretical specific capacity,low cost,and environmental friendliness.However,challenges such as poor intrinsic conductivity,side effects of the inter-face,and structural attenuation are faced by FeF_(2).In this paper,the water-soluble polymer was loaded with metal fluoride precursor by electrostatic spinning technology.After pre-oxidation and carbonization,conductive carbon fiber composites with embedded FeF_(2)nanoparticles(FeF_(2)@NFP)were obtained.The optimal carbonization temperature for FeF2@NFP electrospinning process was ex-plored.During charging/discharging,the carbon matrix of FeF_(2)@NFP can restrain the volume change and phase separation caused by the conversion reaction,to stabilize the structure of the active substance.Besides,the conductive carbon fiber can provide a"fast channel"for electron transport to improve the conductivity of FeF_(2).FeF_(2)@NFP served as cathode material shows an initial reversi-ble specific capacity of 261.55 mAh g^(-1)at 0.1 A g^(-1)current density and excellent cycle stability with a high residual reversible specific capacity of 243.20 mAh g^(-1)and high capacity retention rate of 92.98%after 100 cycles.