The liquid metal battery (LMB) is attractive due to its simple construction, its circumvention of solid-state failure mechanisms and resultantly long lifetimes, and its particularly low levelized cost of energy. Here, we provide a study of a unique binary electrolyte, NaOH-NaI, in order to pursue a low-cost and low-temperature sodium-based liquid metal battery (LMB) for grid-scale electricity storage. Thermodynamic studies have confirmed a low eutectic melting temperature (220°C) as well as provided data to complete the phase diagram of this system. X-ray diffraction has further supported the existence of a recently discovered compound, Na[subscript 7](OH)[subscript 5]I[subscript 2], as well as offered initial evidence toward a NaI-rich compound displaying Pm-3m symmetry. These phase equilibrium data have then been used to optimize parameters from a two-sublattice thermodynamic solution model to provide a starting point for study of higher order systems. Further, a detailed electrochemical study has identified the voltage window and related oxidation/reduction reactions and found greatly improved stability of the pure sodium electrode against the electrolyte. Finally, an Na|NaOH-NaI|Pb-Bi proof-of-concept cell was assembled. This cell achieved over 100 cycles and displayed leakage currents below 0.40 mA/cm[superscript 2]. These results highlight an exciting class of low-melting molten salt electrolytes that may enable low cost grid-scale storage.
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机译:液态金属电池(LMB)的吸引力在于其结构简单,规避了固态故障机制,因而使用寿命长,并且能源成本特别低。在这里,我们提供了一种独特的二元电解质NaOH-NaI的研究,以寻求一种低成本,低温的钠基液态金属电池(LMB),用于电网规模的储能。热力学研究已经证实低共晶熔化温度(220°C)以及提供的数据可以完善该系统的相图。 X射线衍射进一步支持了最近发现的化合物Na [下标7](OH)[下标5] I [下标2]的存在,并为显示Pm-3m对称性的富含NaI的化合物提供了初步证据。 。然后将这些相平衡数据用于优化两个子格热力学求解模型的参数,从而为研究高阶系统提供起点。此外,详细的电化学研究已经确定了电压窗口和相关的氧化/还原反应,并发现纯钠电极对电解质的稳定性大大提高。最后,组装了Na | NaOH-NaI | Pb-Bi概念验证电池。该电池完成了100个循环,并显示出低于0.40 mA / cm [上标2]的泄漏电流。这些结果突出了令人兴奋的一类低熔点熔融盐电解质,可以实现低成本的网格规模存储。
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