Constructing High‐Power N‐Type Thermocells via Fluoride‐Mediated Imidazole–Iodine Coordination
Huaming Yu, Xiaomei Liu, Meilin Li, Hua Zhang, Yaxin Wang, Minshen Zhu, Shaojuan Luo, Xiaofeng Zhang, Zhaopeng Liu, Zhaopeng Liu, Yingguo Yang, Wei Chen, Zhe Hu, Kelang Wang, Wenjun Xu, Zhaodong Huang, Zhuoxin Liu, Zhuoxin Liu, Yang Huang
Abstract
ABSTRACT I − /I 3 − ‐based thermocells show great potential for low‐grade heat harvesting because of their affordability, adjustable electrochemical Seebeck coefficient ( S e ), and ease of device integration. However, current strategies of developing high‐performance I − /I 3 − ‐based thermocells usually result in substantial imbalance between S e and ultimate output power due to deteriorated ion transportation and replenishment. Herein, we propose a novel fluoride‐mediated coordination strategy to break this trade‐off. By introducing potassium fluoride and 1‐(2‐hydroxyethyl)imidazole (HEI) into the electrolyte, we engineer in situ formation of thermosensitive HEI‐I 2 F − coordinated complexes. These complexes undergo reversible temperature‐dependent precipitation and dissociation, creating a significant concentration ratio gradient, thereby remarkably increasing S e . Concurrently, the introduced ligand ions disrupt the original hydrogen bonding of water molecules, facilitating superior ion transport for increased output current. Consequently, the optimized thermocell achieves a high S e of 1.53 mV K −1 and a maximum power density of 124.74 mW m −2 at Δ T = 30 K. This work provides a versatile and effective pathway toward high‐power thermocells for low‐grade heat harvesting.