Thermal Oxidation Gas-Release Strategy for Scalable Synthesis of Porous SnO2 Towards High-Performance Supercapacitor

Conventional strategies for synthesizing porous structures generally depend on template-based methods, which involve not only excessive consumption of templating agents but also the use of hazardous chemicals, such as hydrofluoric acid or strong alkalis. Therefore, designing an effective and convenient strategy to fabricate porous SnO2 is of significant practical relevance. Herein, we developed a top-down strategy to fabricate SnO2 electrode via a thermal oxidation gas-release route, resulting in a bulk 3D hierarchical architecture with interconnected porous channels. Employing a bottom-up strategy, the gel precursors of these porous SnO2 materials were synthesized on a large scale via a simple, surfactant- and template-free route, in accordance with green chemistry principles. The results show that the porous SnO2(300) electrode materials possess a high specific surface area and exhibit favorable electrochemical energy-storage performance, achieving a high specific capacitance of 267.31 F g−1 at a current density of 1 A g−1. Furthermore, based on the gel electrolyte of PVA/KOH, an asymmetric supercapacitor device assembled using porous SnO2(300) materials as the positive electrode and activated carbon as the negative electrode (denoted as P-SnO2//AC) achieves an energy density of 32.49 Wh kg−1 at the power density of 718.97 W kg−1. This work presents a simple, cost-effective, environmentally friendly and scalable approach to synthesize SnO2 materials with an advanced structural design.