Back Cover Image, Volume 7, Number 12, December 2025

Back cover image: Ionomer-bound carbon films in energy devices suffer from frost-driven self-fracture when operating under subzero conditions. In article number e70098, Pyo et al. identify that water freezing within the ionomer binder phase plays a more dominant role in this mechanical degradation than water confined in the nanopores. The authors propose an effective thermal reconfiguration strategy that modifies the ionomer nanostructure to control freezable water domains. This process successfully prevents frost-induced failure, enabling the reconfigured electrodes to maintain over 90% of their initial elongation and ensuring robust low-temperature durability.