Experimental investigations on thermally induced energy storage characteristics of hydrogel thermo-electrochemical cells for low-grade heat recovery

IF 9.4 1区工程技术 Q1 ENERGY & FUELS

Energy Pub Date : 2025-10-06 DOI:10.1016/j.energy.2025.138779

Yilin Jiang , Chengdong Fang , Yanyu Shen , Zhi Li , Xiaoli Yu

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Abstract

Hydrogel thermo-electrochemical cells (also called thermocells or thermogalvanic cells) represent a novel heat-to-power technology driven by temperature difference for harvesting low-grade waste heat. Recently it has been found that hydrogel thermocells possess certain energy storage function with high energy storage density during the thermoelectric conversion process, indicating great potential for harvesting low-grade waste heat. However, the mechanisms behind their energy storage process remain unclear. Most existing studies focus only on materials, which restricts further exploration of their energy storage characteristics. To address this knowledge gap, we prepared typical hydrogel thermocells consisting of graphite electrodes and polyacrylamide (PAAm) hydrogel with K₃[Fe(CN)₆]/K₄[Fe(CN)₆] redox pair electrolytes. We then built a test bench to investigate the energy storage characteristics of hydrogel thermocells under various parametric conditions, including the effects of electrode temperature difference, electrode average temperature, shelving duration, redox pair ion concentration and hydrogel thickness. The above experiments indicate that the energy storage characteristic of hydrogel thermocells originate from the aggregation of ions near the two electrodes during thermoelectric conversion process, but charge storage is achieved by the gel structure to hinder the ion transport and concentration equilibrium after the removing of the temperature difference. The thermally induced energy storage performance is greatly affected by above parameters, for example, the areal capacitance and the energy storage coefficient both decreased by about 57.5 % when the temperature difference of the electrode increases from 10 °C ∼ to 30 °C. This research provides guidance for designing and optimizing energy storage performance of hydrogel thermocells, filling an important void in the field.

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用于低品位热回收的水凝胶热电化学电池热诱导储能特性的实验研究

水凝胶热电化学电池（也称为热电池或热电电池）是一种利用温差驱动的新型热能发电技术，用于收集低品位废热。近年来，人们发现水凝胶热电池在热电转换过程中具有一定的储能功能，储能密度高，在回收低品位废热方面具有很大的潜力。然而，其能量储存过程背后的机制仍不清楚。现有的研究大多集中在材料上，这限制了对其储能特性的进一步探索。为了解决这一知识空白，我们制备了典型的水凝胶热电池，由石墨电极和聚丙烯酰胺（PAAm）水凝胶组成，并具有K3[Fe(CN)6]/K4[Fe(CN)6]氧化还原对电解质。在此基础上，搭建了实验台架，研究了电极温差、电极平均温度、搁置时间、氧化还原对离子浓度和水凝胶厚度对水凝胶热电池储能特性的影响。上述实验表明，水凝胶热电池的储能特性源于热电转换过程中离子在两电极附近聚集，但在消除温差后，通过凝胶结构阻碍离子输运和浓度平衡来实现电荷存储。上述参数对热致储能性能的影响很大，如当电极的温差从10℃~ 30℃增加到30℃时，电极的面电容和储能系数均下降了约57.5%。该研究为水凝胶热电池储能性能的设计和优化提供了指导，填补了该领域的重要空白。

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来源期刊

Energy 工程技术-能源与燃料

CiteScore

15.30

自引率

14.40%

发文量

审稿时长

14.2 weeks

期刊介绍： Energy is a multidisciplinary, international journal that publishes research and analysis in the field of energy engineering. Our aim is to become a leading peer-reviewed platform and a trusted source of information for energy-related topics. The journal covers a range of areas including mechanical engineering, thermal sciences, and energy analysis. We are particularly interested in research on energy modelling, prediction, integrated energy systems, planning, and management. Additionally, we welcome papers on energy conservation, efficiency, biomass and bioenergy, renewable energy, electricity supply and demand, energy storage, buildings, and economic and policy issues. These topics should align with our broader multidisciplinary focus.