Enhanced ion transport in ultrathin regenerated cellulose supercapacitor separators

Abstract

The efficiency of the electrochemical performance of the separator in supercapacitors (SCs) is primarily determined by the ion transport performance, which in turn depends on the pore size uniformity and electrolyte absorption. Cellulose separators with high electrolyte absorption are expected to exhibit outstanding ion transport; however, they remain largely unexplored. Here, we report the fabrication of cellulose separators that feature a hierarchically cross-linked network, and tightly stacked structures can achieve extremely low separator resistivity and enhanced ion transport properties. Compared with common separators, this work enables the investigation of ionic transport in greater detail. High electrolyte absorptivity is realized due to its uniform pore environment, high pore density, hydrophilicity, ultrathin thickness, and reduced impedance, which guarantees the excellent ion transport performance of the separator. The high thermal stability of regenerated cellulose enables the separator to preserve its structural integrity at temperatures as high as 200 °C, thereby ensuring the safety of supercapacitors. This work opens up the application of an ultrathin regenerated cellulose separator with enhanced ion transport performance in large-scale industrialized production with implications that can promote the development of safe and high-performance separators.