Leveraging Nanoparticle Dispersion State To Tune Vanadium Ion Selectivity of Nanophase-Segregated Ionomer Nanocomposites for Redox Flow Batteries
Leveraging Nanoparticle Dispersion State To Tune Vanadium Ion Selectivity of Nanophase-Segregated Ionomer Nanocomposites for Redox Flow Batteries
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DOI：
10.1021/acsaem.9b01443
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发表时间：
2019-12-01
影响因子：
6.4
通讯作者：
Davis, Eric M.
中科院分区：
文献类型：
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作者：
Domhoff, Allison;Balwani, Apoorv;Davis, Eric M.
离聚体纳米复合材料为解决电池(如钒氧化还原液流电池)中用于栅格规模储能的传统离子膜所固有的离子交叉问题提供了一种很有前途的解决方案。在这里，我们研究了纳米颗粒表面化学对纳米颗粒分散性、膜形态和一系列Nafion纳米复合材料中钒离子渗透性的影响。具体地说，二氧化硅纳米颗粒(SiNPs)被功能化了，总共有七个化学部分，这些部分与Nafion中聚集形成离子网络的磺酸基团发生静电相互作用，或者是吸引的，或者是排斥的。从纳米复合材料的电子显微镜分析可以看出，具有磺酸末端官能化的SiNPs平均很好地分散在离聚体膜中，尽管与原始(或未改性)Nafion相比，钒离子渗透性增加，并归因于体系的Donnan电位的变化。相比之下，平均观察到具有胺末端官能化的SiNPs在离聚体膜内形成大的聚集体。令人惊讶的是，纳米颗粒聚集度较高的纳米复合材料显示出最低的钒离子渗透率。对低Q小角中子散射数据的分形分析表明，当纳米粒子表面由磺酸官能化转变为胺官能化时，离聚体与SiNP表面的界面由粗糙向光滑转变。
Ionomer nanocomposites provide a promising solution to address ion crossover issues inherent to traditional ion-containing membranes used in batteries for grid-scale energy storage (e.g., vanadium redox flow batteries). Herein, we investigate the impact of nanoparticle surface chemistry on nanoparticle dispersion, membrane morphology, and vanadium ion permeability in a series of Nafion nanocomposites. Specifically, silica nanoparticles (SiNPs) were functionalized with various chemical moieties, seven in total, that electrostatically interact, either attractively or repulsively, with the sulfonic acid groups that coalesce to form the ionic network within Nafion. As seen from electron microscopy analysis of the nanocomposites, SiNPs with sulfonic acid end-functionality were, on average, well dispersed within the ionomer membrane, though increased vanadium ion permeability, as compared to pristine (or unmodified) Nafion, was observed and attributed to changes in the Donnan potential of the system. In contrast, SiNPs with amine end-functionality were, on average, observed to form large aggregates within the ionomer membrane. Surprisingly, nanocomposites containing a higher degree of nanoparticle aggregation demonstrated the lowest vanadium ion permeability. Fractal analysis of the low-Q small-angle neutron scattering data suggests that the interface between the ionomer and the SiNP surface transitions from rough to smooth when the nanoparticle surface is changed from sulfonic acid-functionalized to amine-functionalized.