High-Capacity Molecular Scale Conversion Anode Enabled by Hybridizing Cluster-Type Framework of High Loading with Amino-Functionalized Graphene
High-Capacity Molecular Scale Conversion Anode Enabled by Hybridizing Cluster-Type Framework of High Loading with Amino-Functionalized Graphene
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通过与氨基功能化石墨烯杂化高负载簇型框架实现高容量分子尺度转换阳极
DOI：
10.1021/acsnano.6b01321
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发表时间：
2016
期刊：
影响因子：
17.1
通讯作者：
Li Chilin
中科院分区：
文献类型：
--
作者：
Xie Junjie;Zhang Ye;Han Yanlin;Li Chilin
开发具有多电子反应、足够的电荷/质量传递和抑制体积膨胀的高容量阳极是非常需要的。由独立结构单元组成的具有转化反应潜力的开放骨架可以满足这些要求，并显示出常规插入型开放骨架最多一个电子转移或具有紧密配体键合的转化材料的优势。在这里，我们报告了一类电化学稳定的簇状聚氧乙烯酸盐（POM）作为这样的开放框架阳极。它们的高负载和低溶解度是通过Al或Si驱动的聚合和与带正电的石墨烯的杂交实现的，这固定了POM的聚阴离子并改善了它们的电接触。用于锂存储的铝基POM复合材料（NAM-EDAG）实现了高于1000 mAh g-1的高可逆容量，并且耐受超过1100次循环的长期循环和高达20 A g-1的电流密度。在分子尺度上发生的六电子转换反应以及随后受益于原始开放框架的产物的优化分布也是高电活性的原因。基于POM的开放框架为探索由用于Li和Na存储的电活性分子或簇部分组成的先进的、不太可溶（或不可溶）的框架材料提供了灵感。
Exploring high-capacity anodes with multielectron reaction, sufficient charge/mass transfer, and suppressed volume expansion is highly desired. The open frameworks consisting of independent structure units, which possess conversion reaction potentiality, can meet these demands and show advantages over routine insertion-type open frameworks with at most one-electron transfer or conversion materials with compact ligand linkage. Here, we report a class of electrochemically stable cluster-like polyoxometalates (POMs) as such open framework anodes. Their high loading and low solubility are enabled by Al- or Si-driven polymerization and hybridization with positively charged graphene, which immobilizes polyanions of POMs and improves their electric contact. Al-based POM composite (NAM–EDAG) for Li-storage achieves a high reversible capacity above 1000 mAh g–1and tolerates a long-term cycling with more than 1100 cycles and a current density up to 20 A g–1. A six-electron conversion reaction occurring at molecular scale and the consequent optimized distribution of products benefiting from original open framework are also responsible for the high electroactivity. POM-based open frameworks give inspiration for exploring advanced, less soluble (or insoluble) framework materials made up of electroactive molecule or cluster moieties for Li- and Na-storage.