氮掺杂冰粉基碳包覆Fe_(3)O_(4)及其储锂性能研究

Nitrogen-doped ice jelly powder-based carbon-coated Fe_(3)O_(4) and its lithium storage performance

碳包覆策略是能有效解决锂离子电池负极用过渡金属氧化物(TMO)材料在充放电过程中体积膨胀/收缩造成的粉化难题的一种有效途径。采用生物基可食用冰粉作为碳源与草酸高铁铵的水凝胶作为前驱物,经一步高温热解制备氮掺杂的冰粉基碳包覆Fe_(3)O_(4),采用XRD、SEM、TEM、XPS、TGA、拉曼光谱、恒电流充放电测试、循环伏安和电化学阻抗谱等方法对样品的形貌、结构和电化学性能进行研究。结果表明,该方法可快速大量制备氮掺杂碳包覆Fe_(3)O_(4)多孔复合材料(N-C@Fe_(3)O_(4)),通过调整原料配比和热处理条件,获得优异的电化学性能。N-C@Fe_(3)O_(4)-5作为锂离子电池负极材料具有良好的循环稳定性(在0.1 A/g电流密度下循环下80圈保持762.74 mAh/g比容量)和较高的倍率性能。相关机理研究表明N-C@Fe_(3)O_(4)复合材料良好倍率性能主要来源于赝电容容量的贡献。复合材料优异的电化学性能是由于碳包覆能够防止纳米颗粒团聚,提高导电性以及形成稳定的固体电解质界面(SEI)膜。冰粉基碳包覆TMO是一种改善其电化学储锂性能的有效途径,可推广并改善其他锂离子电池氧化物负极的储锂性能。

The carbon coating strategy is an effective way to solve the pulverization problem caused by the volume expansion/shrinkage of transition metal oxide(TMO)materials for lithium-ion battery anodes during charge and discharge.In this paper,bio-based edible ice jelly powder was used as carbon source and ferric ammonium oxalate hydrogel was used as precursor,and nitrogen-doped ice jelly powder-based carbon-coated Fe_(3)O_(4) was prepared by one-step high-temperature pyrolysis.The morphology,structure and electrochemical properties of the samples were studied by XRD,SEM,TEM,XPS,TGA,Raman spectroscopy,galvanostatic charge-discharge test,cyclic voltammetry and electrochemical impedance spectroscopy.The results show that this method can quickly and massively prepare nitrogen-doped carbon-coated Fe_(3)O_(4) porous composites(N-C@Fe_(3)O_(4)),and excellent electrochemical performance can be obtained by adjusting the ratio of raw materials and heat treatment conditions.N-C@Fe_(3)O_(4)-5 as a lithium ion battery anode material has good cycle stability(762.74 mAh/g specific capacity after 80 cycles at a current density of 0.1 A/g)and high rate capability.Relevant mechanism studies have shown that the good rate performance of N-C@Fe_(3)O_(4) composites is mainly due to the contribution of pseudocapacitive capacity.The excellent electrochemical performance of the composite is attributed to the carbon coating that prevents nanoparticle agglomeration,improves electrical conductivity,and forms a stable solid electrolyte interface(SEI)film.This work shows that ice jelly powder-based carbon-coated TMO is an effective way to improve the electrochemical lithium storage performance of TMO,which can be extended and improved the lithium storage performance of other lithium-ion battery oxide anodes.