High‐Performance Self‐Assembled Amphiphilic Block Copolymer Thermoelectric Ionogel for Low‐Humidity Heat Harvesting

ABSTRACT

Ionic thermoelectric (i‐TE) materials have attracted considerable interest due to their abilities to generate high thermovoltage for low‐grade waste heat harvesting. However, challenge still remains to develop high‐performance i‐TE materials, especially at relative low humidity (RH) range <60%. Herein, i‐TE ionogels based on cross‐linked Pluronic block copolymer (PEO _x ‐PPO _y ‐PEO _x ) diacrylate and ionic liquid with simultaneously enhanced ionic conductivity and ionic Seebeck coefficient were developed. Benefiting from the amphiphilic nature of Pluronic block copolymers, self‐assembled micelles spontaneously form in ionogels, leading to a controllable nanophase‐separated micellar structure, while crosslinking suppresses PEO crystallization. This unique structure promotes continuous ion‐transport pathways and leads to high ionic conductivity. In addition, the intermolecular interactions between ions and block copolymer backbones could be tuned by different PO block ratios in Pluronic block copolymers. Consequently, the Pluronic P123DA ionogel exhibited an exceptional σ _i of 4.29 S m ⁻¹ , S _i of 18.2 mV K ⁻¹ and corresponding PF of 1422.4 µW m ⁻¹ K ⁻² and ZT _i of 1.89 at RH of 55%. This design of amphiphilic Pluronic‐DA ionogels provides a versatile strategy for high‐performance i‐TE ionogels for promising low‐humidity low‐grade heat harvesting applications.