Electronic Supplementary Materials

In situ nitrogen-doped carbon nano-onions for ultrahigh-rate

asymmetric supercapacitor

Debananda Mohapatra,1 Muhammad Olvianas,1 Mostafa Saad Sayed,1,3 Smrutiranjan Parida,2,*

and Jae-Jin Shim1,*

1School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk

38541, Republic of Korea. E-mail: jjshim@yu.ac.kr; Tel: +82-53-810-2587

2Department of Metallurgical Engineering and Materials Science, IIT Bombay, Powai,

Mumbai 400-076, India. E-mail: paridasm@iitb.ac.in; Tel: +91-22-2576-7643

3Analysis and Evaluation Department, Egyptian Petroleum Research Institute, Nasr City, Cairo

11727, Egypt

* Corresponding Authors: Jae-Jin Shim (jjshim@yu.ac.kr)

Smrutiranjan Parida (paridasm@iitb.ac.in)

S1

1. XRD and FE-SEM of NiO

The crystallinity of NiO was investigated by XRD, as shown in Fig. S1a. The XRD patterns

of the as-prepared NiO was well-matched with the standard NiO JCPDS file 004-9047,

conforming the crystalline hexagonal phase. The morphology of NiO sample was further

investigated using FE-SEM, as shown in Fig. S1b, c.

Figure S1. XRD (a) and FE-SEM images (b, c) of the as-prepared NiO.

S2

2. BET specific surface area and pore size distribution of N-CNO

Figure S2. N2 adsorption-desorption isotherms (a) and BJH desorption PSD (b) of N-CNOs.

S3

3. Electrochemical responses of N-CNO and NiO electrodes in the three-

electrode configuration

Figure S3. Electrochemical response of (a) N-CNO electrode and (b) NiO electrode in 1 M

Na2SO4 electrolyte in a three-electrode system; (c) comparative cyclic voltammograms of N-

CNO and NiO as a negative electrode and a positive electrode, respectively, at a scan rate of 10

mV s−1 in a three-electrode system.

S4

4. Electrochemical performance of N-CNO||N-CNO symmetric device and N-

CNO//NiO asymmetric device

Figure S4. Cyclic voltammograms at different scan rates (a), and GCD curves at different

current densities (b), variation in the specific capacitance with current density (c), and Ragone

plot (d) of the N-CNO||N-CNO symmetric device.

S5

Figure S5. Variation in the specific capacitance with current density of N-CNO//NiO

asymmetric device.

S6