npj: 金属氟化物—释放电化学储能潜力
海归学者发起的公益学术平台
分享信息，整合资源
交流学术，偶尔风月
后锂离子电池（LIBs）时代的电池正在成为未来储能的重要组成部分。在后LIB技术中，钠离子电池（NIBs）是个先行者。但由于钠嵌入型正极材料的操作电位较低和分子量较高，目前钠离子电池的能量密度显著低于锂离子电池。NIB要想成为能与LIB的高能量密度相媲美的体系，探索合成和使用高电压的正极材料成为关键。
来自德国乌尔姆亥姆霍兹研究所M. Anji Reddy领导的研究小组，筛查了一些真实和虚拟的化合物，发现weberite型金属氟化物有潜力作为NIB的高电压正极材料。虽然他们将研究限定于考查仅一定数量的化合物，但这些材料的范围极其各种修饰的可能性将非常大。除了不同元素组合外，通过多种物种填充每个金属亚晶格也可能是有意义的，这可促进更快的扩散途径的形成同时，又可保持高的能量密度，以使化合物实现进一步的优化。按照这一策略，他们将一些高能量密度的材料与一定量的Ti合金化，以形成快速的扩散通道。他们的研究从理论角度证明了这些材料具有作为NIB正极材料的潜力，作者希望未来的研究会开启这些化合物的合成和实验测试。
该文近期发表于npj Computational Materials 5: 31 (2019)，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。
Unlocking the potential of weberite-type metal fluorides in electrochemical energy storage
Holger Euchner, Oliver Clemens & M. Anji Reddy
Abstract Sodium-ion batteries (NIBs) are a front-runner among the alternative battery technologies suggested for substituting the state-of-the-art lithium-ion batteries (LIBs). The specific energy of Na-ion batteries is significantly lower than that of LIBs, which is mainly due to the lower operating potentials and higher molecular weight of sodium insertion cathode materials. To compete with the high energy density of LIBs, high voltage cathode materials are required for NIBs. Here we report a theoretical investigation on weberite-type sodium metal fluorides (SMFs), a new class of high voltage and high energy density materials which are so far unexplored as cathode materials for NIBs. The weberite structure type is highly favorable for sodium-containing transition metal fluorides, with a large variety of transition metal combinations (M, M’) adopting the corresponding Na2MM’F7 structure.. A series of known and hypothetical compounds with weberite-type structure were computationally investigated to evaluate their potential as cathode materials for NIBs. Weberite-type SMFs show two-dimensional pathways for Na+ diffusion with surprisingly low activation barriers. The high energy density combined with low diffusion barriers for Na+ makes this type of compounds promising candidates for cathode materials in NIBs.
扩展阅读
本文系网易新闻·网易号“各有态度”特色内容
媒体转载联系授权请看下方