Low-crystalline iron oxide hydroxide nanoparticle anode for high-performance supercapacitors

Abstract

Carbon materials are generally preferred as anodes in supercapacitors; however, their low capacitance limits the attained energy density of supercapacitor devices with aqueous electrolytes. Here, we report a low-crystalline iron oxide hydroxide nanoparticle anode with comprehensive electrochemical performance at a wide potential window. The iron oxide hydroxide nanoparticles present capacitances of 1,066 and 716 F g ⁻¹ at mass loadings of 1.6 and 9.1 mg cm ⁻², respectively, a rate capability with 74.6% of capacitance retention at 30 A g ⁻¹, and cycling stability retaining 91% of capacitance after 10,000 cycles. The performance is attributed to a dominant capacitive charge-storage mechanism. An aqueous hybrid supercapacitor based on the iron oxide hydroxide anode shows stability during float voltage test for 450 h and an energy density of 104 Wh kg ⁻¹ at a power density of 1.27 kW kg ⁻¹. A packaged device delivers gravimetric and volumetric energy densities of 33.14 Wh kg ⁻¹ and 17.24 Wh l ⁻¹, respectively.

Abstract

Carbons dominate anode materials for supercapacitors, however the attained energy density remains low. Here the authors fabricate low-crystalline iron oxide-hydroxide nanoparticle anodes with good electrochemical characteristics, exhibiting high stability and energy/power densities in a hybrid supercapacitor.