高质量水系钠离子电池正极Fe4[Fe（CN）6]3的合成及其电化学性能

High-quality Fe4[Fe（CN）6]3 Nanocubes: Synthesis and Electrochemical Performance as Cathode Material for Aqueous Sodium-ion Battery

采用水热法合成高质量的Fe4[Fe(CN)6]3(HQ-FeHCF)纳米材料,并对材料进行X射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM)和热重分析测试(TGA)等表征。结果表明:Fe4[Fe(CN)6]3呈规则立方体,颗粒大小约500 nm,属面心立方结构。Fe4[Fe(CN)6]3在NaClO4 H2O聚乙二醇电解液中1C、2C、5C、10C、20C、30C和40C的容量分别为124、118、105、94、83、74和64 mAh g 1,表现出优异的倍率性能;以5C倍率循环500次,容量保持率接近100%,表现出极佳的循环稳定性。以Fe4[Fe(CN)6]3和磷酸钛钠分别为正负极的全电池工作电压高达1.9 V,能量密度可达126 Wh kg 1;以5C倍率恒流充放电测试140次后全电池容量保持率为92%,且库伦效率始终接近100%。

High-quality Fe4[Fe(CN)6]3(HQ-FeHCF)nanocubes were synthesized by a simple hydrothermal method.Its structure,morphology and water content are characterized.Fe4[Fe(CN)6]3 exhibits regular cubic shape with a uni-form size of ca.500 nm,which belongs to the face-centered cubic phase.Fe4[Fe(CN)6]3 shows discharge capacities of 124,118,105,94,83,74 and 64 mAh g 1 at 1C,2C,5C,10C,20C,30C and 40C rate,respectively,in the aqueous ternary electrolyte of NaClO4-H2O-Polyethylene glycol.Its capacity retention remains 100%after 500 charge/discharge cycles at the rate of 5C.The full battery with Fe4[Fe(CN)6]3 as cathode and NaTi2(PO4)3 as anode was fabricated,which delivers a specific energy density of 126 Wh kg 1(based on the active electrode materials)with a voltage output of 1.9 V.Furthermore,92%of its initial discharge capacity retains after 140 charge/discharge cycles at a rate of 5C,and its Coulomb efficiency is close to 100%.