Heterogeneous Side-Chain Polymers Provide High-Speed Migration Pathways for Li⁺ in Ionogels, Enabling High-Performance Infrared Electrochromic Supercapacitors

Efficient Li⁺ transport is essential for achieving high-performance ionogel polymer electrolytes (IPEs). However, in the IPEs, Li⁺ transport is severely hindered by strong coordination with the anions of ionic liquids and polymer segments. Here, we propose a polymeric heterogenous side-chain strategy that selectively accelerates Li⁺ migration in IPEs. The flexible and polar side chains provided by 2-(2-Ethoxyethoxy)ethyl acrylate coordinate with Li⁺, effectively releasing Li⁺ from [Li(anion)_n]⁻⁽ⁿ⁻¹⁾ clusters, while another positively charged side chains mitigate Li⁺–polymer interactions, further promoting Li⁺ mobility. These dual-function polymers prevent Li⁺ from becoming trapped within [Li(anion)_n]⁻⁽ⁿ⁻¹⁾ clusters and facilitate rapid hopping transport of Li⁺ with minimal resistance at polymer sites, ultimately enabling efficient Li⁺ transport. As a result, the IPEs exhibit enhanced high Li⁺ transference number (0.6) and ionic conductivity (4.6 mS cm⁻¹). Benefiting from enhanced Li⁺ transport of IPEs, infrared electrochromic supercapacitors (IR-EC-SC) exhibit outstanding IR electrochromic performance (0.45, 8–14 µm) and energy storage capabilities (222.3 F g⁻¹, 1A g⁻¹). In addition, the IR-EC-SC exhibits rapid response times and remains operational after 15 000 cycles. This work demonstrates new insights into the regulation of Li⁺ transport in IPEs, offering a promising pathway toward high-performance IR-EC-SC for advanced thermal management, smart optical applications, and energy storage applications.