蛋黄壳结构FeF_(3)·0.33H_(2)O@N掺杂碳纳米笼正极材料的构筑及其电化学性能  

Construction and Electrochemical Properties of Yolk-shell Structured FeF_(3)·0.33H_(2)O@N-doped Graphene Nanoboxes

作　　者：程节 周月 罗薪涛 高美婷 骆思妃 蔡丹敏 吴雪垠 朱立才[1] 袁中直[1] CHENG Jie;ZHOU Yue;LUO Xintao;GAO Meiting;LUO Sifei;CAI Danmin;WU Xueyin;ZHU Licai;YUAN Zhongzhi(School of Chemistry,South China Normal University,Guangzhou 510006,China)

机构地区：[1]华南师范大学化学学院,广州510006

出　　处：《无机材料学报》2024年第3期299-305,I0003,I0004,共9页Journal of Inorganic Materials

摘　　要：FeF_(3)·0.33H_(2)O具有理论容量和电压高的特点,但其导电性差、氧化还原反应过程中体积变化严重导致电化学循环性能不佳,应用受到限制。本研究采用多巴胺自组装包覆纳米立方Fe_(2)O_(3)颗粒,再经过碳化、HCl刻蚀和HF氟化的策略,合成了由N掺杂石墨烯外壳和纳米立方FeF_(3)··0.33H_(2)O内核所构成的蛋黄壳结构复合材料FeF_(3)·0.33H_(2)O@CNBs,粒径约250 nm,碳壳厚度为30~40 nm。FeF_(3)·0.33H_(2)O@CNBs在0.2C(1C=237 mA·g^(-1))电流密度下充放电初始容量为208 mAh·g^(-1),循环50圈之后容量仍然有173 mAh·g^(-1),每圈容量衰减率仅为0.3%;而纯FeF_(3)·0.33H_(2)O初始容量只有112 mAh·g^(-1),循环50圈之后只有95 mAh·g^(-1)。FeF_(3)·0.33H_(2)O@CNBs的循环性能明显优于FeF_(3)·0.33H_(2)O,同时0.1C~1C充放电结果表明其倍率性能也明显优于FeF_(3)·0.33H_(2)O。这是因为该策略制备的N掺杂石墨烯外壳提供了良好的电子/离子输运性能,同时碳壳可缓冲和抑制内核FeF_(3)·0.33H_(2)O的体积变化,其空隙体积对电解液的储液保液性能缩短了离子迁移距离,提升了Li+迁移速率,从而得到了比文献报道更好的电化学性能。FeF_(3)·0.33H_(2)O possesses the characteristics of high theoretical capacity and high voltage,but its electrochemical cycling performance is unsatisfactory due to its poor conductivity and serious volume change during redox reaction,resulting in limited application.In this study,by using the strategies of dopamine self-assembly coating,carbonization,HCl etching and HF fluorination,the yolk-shell structured composite FeF_(3)·0.33H_(2)O@carbon nanoboxes(FeF_(3)·0.33H_(2)O@CNBs)composed of N-doped graphene shell and nanocube FeF_(3)·0.33H_(2)O core was synthesized.Its particle size is about 250 nm and thickness of carbon shell is 30–40 nm.FeF_(3)·0.33H_(2)O@CNBs displays an initial charge-discharge capacity of 208 mAh·g^(-1)at a current density of 0.2C(1C=237 mA·g^(-1)).After 50 cycles,the capacity remains 173 mAh·g^(-1),and the capacity attenuation rate per cycle is only 0.3%.In comparison,the initial capacity of bare FeF_(3)·0.33H_(2)O is 112 mAh·g^(-1),and after 50 cycles,only 95 mAh·g^(-1)reserves,indicating superior cycle performance of FeF_(3)·0.33H_(2)[e-mail],charging and discharging results at 0.1C–1C show that the rate performance is also significantly better than bare FeF_(3)·0.33H_(2)O.It’s due to that N-doped graphene shell prepared by this strategy provides good electron/ion transport performance.At the same time,the carbon shell can not only buffer and inhibit the volume change of the core FeF_(3)·0.33H_(2)O,but also shorten the ion migration distance and improve the Li+migration rate on the electrolyte storage and retention performance of the electrolyte.As a result,the electrochemical performances are better than those of previous literature.

关 键 词：锂离子电池 电极材料 氟化铁 蛋黄壳结构 

分 类 号：O646[理学—物理化学]