A Hybrid All-Solid-State Supercapacitor Using a Dry Multilayered Graphene Oxide Electrolyte Assembly: Understanding the Charging Dynamics from Experimental and Molecular Simulation Studies

Research in supercapacitors is essential for driving innovation in energy storage, paving the way for a more sustainable and efficient future where technology and the environment coexist in harmony. Supercapacitors can instantly provide higher energy density than conventional capacitors and higher power density than batteries, despite limitations of low volumetric performance. Here, we show a simplified way to manufacture a hybrid all-solid-state supercapacitor operating at room temperature and dry conditions based on poly-(diallyldimethylammonium chloride) (PDDA)/graphene oxide (GO) multilayer assembly using the layer-by-layer technique. They display rapid discharge (relaxation time constant, τ₀ down to 1 μs), high energy (up to 7 Wh/kg) and power (up to 1400 W/kg) densities, and specific capacitance (up to 12 F/g). Molecular dynamics simulations of a PDDA/GO system are performed with and without water molecules, highlighting the crucial role of chlorine in the system's structure. The charge storage and fast discharge, LbL thickness control, and film conformability on practically any surface are attractive approaches in numerous practical applications. Besides simplifying the system, the exclusion of liquid electrolytes and the use of ultrathin films are advantageous in several applications, without compromising weight in structures.