Highly Efficient and Stable Cellulose-Based Ion Gel Polymer Electrolyte for Solid-State Supercapacitors

To solve the current situation of low efficiency and instability of SCs, herein, the regenerated cellulose nanoparticles are applied on the electrolyte for the first time and a kind of solid-state SC with high performance is synthesized in a facile way. The electrolyte is prepared taking copolymer poly(vinyl alcohol) (PVA) as the polymer matrix, 1-butyl-3-methylimidazolium trifluoromethansulfonate (BmimCF3SO3) as the supporting electrolyte, graphene oxide as the ionic conducting promoter, and regenerated cellulose nanoparticles as the regulator. This doped ion gel significantly improves the charge-transfer resistance, because the homogeneously distributed regenerated cellulose nanoparticles make the ion transmission more orderly and stable and then reduce charge transfer resistance greatly. A model of the transmission of ions in the novel electrolyte is proposed. The cellulose-based gel electrolyte enables the SC to show good capacity retention of about 80%, and its charge/discharge efficiency maintains at 98% after 10,000 cycles. Those satisfactory performances are due to the high ionic conductivity, excellent compatibility with carbon electrodes and long-term stability of the doped ion gel. Attributed to the simple procedure and its components, the gel electrolyte is highly scalable, cost-effective, safe, and nontoxic as well as has application potential in various energy storage and delivery systems.