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Engineering the Electrochemical Temperature Coefficient for Efficient Low‐Grade Heat Harvesting
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2018-07-12 , DOI: 10.1002/adfm.201803129
Caitian Gao 1 , Yuling Yin 2 , Lu Zheng 3 , Yezhou Liu 1 , Soojin Sim 1 , Yongmin He 3 , Chao Zhu 3 , Zheng Liu 3 , Hyun-Wook Lee 4 , Qinghong Yuan 2 , Seok Woo Lee 1
Affiliation  

Low‐grade heat to electricity conversion has shown a large potential for sustainable energy supply. Recently, the low‐grade heat harvesting in the thermally regenerative electrochemical cycle (TREC) is a promising candidate with high energy conversion efficiency. In this system, the electrochemical temperature coefficient (α) plays a dominant role in efficient heat harvesting. However, the internal factors that affect α are still not clear and significant improvements are needed. Here, α of various Prussian Blue analogues (PBAs) is investigated and their lattice change during cation intercalation is monitored using the ex situ X‐ray diffraction (XRD) method. For the first time, it is found that α is highly related to the lattice parameter change. Large lattice shrinkage exhibits a large negative α, while lattice expansion is corresponding to a positive α. These are mainly attributed to the different phonon vibration entropy changes upon cation intercalation in various PBAs. Especially, purple cobalt hexacynoferrate delivers the largest α of −0.89 mV K−1 and enables highly efficient heat conversion efficiency up to 2.65% (21% of relative efficiency). The results of this study provide a fundamental understanding of temperature coefficient in electrochemical reactions and pave the way for designing high‐performance material for low‐grade heat harvesting.

中文翻译:

设计电化学温度系数以有效地进行低品位热量收集

低品位的热能转化为电能已显示出可持续能源供应的巨大潜力。近年来,热再生电化学循环(TREC)中的低品位热量收集是一种具有高能量转换效率的有前途的候选者。在该系统中,电化学温度系数(α)在有效的热量收集中起主要作用。但是,影响α的内部因素仍然不清楚,需要进行重大改进。在这里,研究了各种普鲁士蓝类似物(PBA)的α,并使用异位X射线衍射(XRD)方法监测了它们在阳离子嵌入过程中的晶格变化。首次发现,α与晶格参数变化高度相关。大的晶格收缩率表现出较大的负α值,而晶格扩展对应于正α。这些主要归因于各种PBA中阳离子嵌入后声子振动熵的不同变化。尤其是,六氰合高铁酸钴钴的最大α值为-0.89 mV K-1,实现高达2.65%(相对效率的21%)的高效热转换效率。这项研究的结果为电化学反应中的温度系数提供了基本的理解,并为设计用于低等级集热的高性能材料铺平了道路。
更新日期:2018-07-12
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