High capacitance B/C/N composites for capacitor electrodes synthesized by a simple method

The B/C/N composites were synthesized by a very simple method. that is, carbonization at HTT = 800-1200 degrees C of the precursor prepared by drying a solution mixture of polyacrylamide and boric acid, followed by boiling in water to remove borate by-products The amount of insoluble B species in I lie composite increased linearly from 4 8 to 18.6 mass% with raising HTT The XRD and FT-IR revealed that turbostratic h-BN started to form at around 1000 degrees C as a by-product. By XPS. major B and N components in I lie compost le were B-N bond. C-B-O type B. pyridinic N. pyrrolic N, and quaternary N A fraction for B-N bond including h-BN in the total B or N components increased with raising HTT and it exceeded 50 at % between 900 and 1000 C. It Was Suggested that in the composites formed at HTT > 1000 degrees C the amounts of h-BN increased, leading to reduction in other B and N components. The S(BET) was almost unchanged up to 1000 C. 410-420 m(2) g(-1). Large and broad redox peaks arisen from plural reactions appeared in the cyclic voltammogram (CV) measured in 1 mol dm(-3) H(2)SO(4) for the composites formed at HTT <= 1000 degrees C. These peaks disappeared in 1 mol dm(-3) solutions of Na(2)SO(4) and Li(2)SO(4). By comparing CV with that for C/N composite formed from PAA by the MgO template method, the pseudo-capacitance owing to reactions of B-N and C-B-O components with protons Was found to be added to commonly observed pseudo-capacitance for nitrogen-cloped carbons The capacitances foi tile composites foinied at 850-950 degrees C exceeded 300 Fg(-1) at 2 mV s(-1) in the acid electrolyte and the retention at 50 mV s(-1) was 78-80% The shape of CV in the neutral electrolytes was trapezoid and the Current density increased with lowering potential, suggesting adsorption and desorption of Na(+) and Li(+) ions This was considered to be due to doped nitrogen indicating the development of pseudo-capacitance the capacitance per S(BET) was 0.33-074 F m(-2) and 017-032 F m(-2). larger for lower HTT, it, the acid and neutral electrolytes, respectively. (C) 2009 Elsevier B.V. All rights reserved.