Nanocomposites and nanomaterials
The influence of isothermal annealing on electrochemical properties of carbon materials
A. I. Kachmar1, B.I. Rachii1, I.M. Budzuliak1
1 Vasyl Stefanyk Precarpathian National University, Ivano-Frankivsk-76000, Ukraine. 
E-mail: andrij.nj@gmail.com

Carbon raw was activated with sodium hydroxide. Activated carbon materials (ACM), that were used as an electrode material for electrochemical supercapacitors, were annealed at different temperatures, with different ratio material/activating agent, and some samples were double activated (table.1).
Table. 1. ACM sample marking 
Sample	m(NaOH)⁄m(C)	Annealing temperature, °С	Conductive additive	Activation number	Specific capacitance of porous carbon material (PCM) at 1 мА, F/g	
NC025600S1	1/4	600	Acetylene black	1	43	
NC05600S1	1/2	600	Acetylene black	1	47	
NC075600T1	3/4	600	Thermoexpandable graphite	1	61	
NC075600S1	3/4	600	Acetylene black	1	71	
NC075600S2	3/4	600	Acetylene black	2	100	
NC1600S1	1/1	600	Acetylene black	1	71	
NC1600S2	1/1	600	Acetylene black	2	88	
NC025900S1	1/4	900	Acetylene black	1	31	
NC05900S1	1/2	900	Acetylene black	1	35	
NC075900S1	3/4	900	Acetylene black	1	77	
NC075900S2	3/4	900	Acetylene black	2	83	
NC1900S1	1/1	900	Acetylene black	1	125	
NC1900S2	1/1	900	Acetylene black	2	100	

a)					b)

Fig 1. Specific capacitance dependencies of annealed at 600°С(a) and 900°С (b) porous carbon material on discharge current.

All the sample series were activated at the temperature of 600°С, washed till pH is neutral and dried at 90°С. Based on these samples the electrodes for double-electrode cells of “2525” standard size were made. KOH 33% solution was used as an electrolyte [1].
Based on galvanostatic data specific capacitance for all the samples was calculated to analyze how annealing temperature and carbon material/activating agent ratio affect the specific energy-intensive characteristics of the obtained PCM [2, 3].
It was established, that annealing at 600°С allows obtaining of carbon material with the highest value of specific capacitance – 100 F/g (at m(NaOH)⁄m(C)=1/4 and double activation) and the one at the temperature of 900°С – 125 F/g (at m(NaOH)⁄m(C)=1/1) at the discharge current of 1 mA.

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2.	Kurzweil P. AC Impedance Spectroscopy – a powerful tool for the characterrization of materials and electrochemical power sources // Proceedings The 12-th International Seminar on Double Layer Capacitors and Similar Energy Storage Devices. – Deerfield Beach, Florida, USA, 2004. –V. 14. – P. 18−32.
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