Durable, rate-capable and high-energy hybrid supercapacitor from PANI/ZnO/SnO2 nanocomposite with zero-waste electrolyte approach

Abstract

A hybrid supercapacitor material, polyaniline/ZnO/SnO₂ of respective weight percentages of 58.34%:8.33%:33.33% (PZnSn), was synthesized by a facile in situ single-step method. Remarkably, the constituent ZnO was synthesized at 90 °C by this method along with the other two constituents in 2 h. This is astonishing because, the synthesis of ZnO generally involves calcination at high temperature for a longer duration. The energy storage performance was evaluated with two aqueous electrolytes: 1 M H₂SO₄ (SA) and the liquid by-product that was obtained after the synthesis of PANI (SLP). SLP provided 57.25% higher energy storage performance than that provided by SA. PZnSn showed its durability and rate-capable energy storage property by exhibiting robustness up to 16 500 cycles at 0.4 V s⁻¹ and 39 A g⁻¹ in the presence of (ITPO) SA and up to 15 000 cycles at 0.4 V s⁻¹ and 42 A g⁻¹, respectively, ITPO SLP, in a real-time symmetric two-electrode system. PZnSn displayed the remarkable trait of enhancement of energy storage with an increase in the number of charge and discharge cycles ITPO both electrolytes. However, the enhancement provided by SLP is higher than that provided by SA. The maximum performance achieved from PZnSn ITPO SLP is a specific capacity (Q) of 347.2 C g⁻¹, a specific energy (E) of 57.87 W h kg⁻¹ (comparable to Ni–Cd batteries) and a specific power (P) of 1.2 kW kg⁻¹ at 1 A g⁻¹.