Electronic Supplementary Material (ESI) for RSC Advances. This journal is © The Royal Society of 2016

Supporting

Chemical synthesis of 3D copper sulfide with different morphologies for high performance supercapacitors application

Ravindra N. Bulakhea, Sumanta Sahooa, Thi Toan Nguyena, Chandrakant D. Lokhandeb, Changhyun Rohc, Yong Rok Lee,a Jae-Jin Shima* a School of Chemical , Yeungnam , , Gyeongbuk, 712-749, Republic of b Thin Film , Department of Physics, Shivaji University, Kolhapur- 416 004, (M.S.), . c Radiation Division for , Advanced Radiation Institute, Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Deajeon 305-353, Republic of Korea.

CORRESPONDING AUTHOR FOOTNOTE *Prof. Jae- Jin Shim, Supercritical Fluids Nano Processes Laboratory #302, School of , Yeungnam University, 241-1 Dae-dong, Gyeongsan, Gyeongbuk, 712-749 Tel.: +82 53 810 2587; fax: +82 53 810 2587. E-mail address: [email protected]. Supporting Information S1

In beaker ‘A’ consisting of an aqueous solution of 0.1M CuSO4 as cationic precursor and 0.1

M liquid ammonia solution (AMM)/hexamethyltetrammine (HMT) used separately acts as

the complexing agent. The reaction with thiourea (H2NCSH2N) was achieved in beaker ‘C’

using 0.01 M thiourea solution of pH~ 6 acts as anionic precursor as well as reducing agent to reduce Cu2+ to Cu1+. The beaker ‘B’ and ‘D’ with deionized water were used for rinsing purpose. Supporting Information S2

Fig. a, b shows schematic of probable steps involved in the SILAR mechanism. i) Initially

Cu+ ions are adsorbed on the surface of substrate then S- - ions attached to ions Cu+ from cationic and anionic precursor ii) Cu+ and S- - ions combines on the substrate to form layer by layer Cu2S nuclei. iii) Continued growth of Cu2S crystals, form a flower like/ nano wire structures for Cu:AMM AND Cu:HMT electrodes, respectively. iv) The actual SEM image is shown for Cu:AMM AND Cu:HMT electrodes. Supporting Information S3

The fig. a, b shows the selected area energy dispersion (SAED) pattern of Cu:

AMM and Cu: HMT electrodes, respectively. It confirms the polycrystalline nature of the Cu2S materials in both cases.

Supporting Information S4

Supercapacitor calculations

The capacitance (C) was calculated using following relation,

퐼푚푎푥 퐶 = 푑푣/푑푡 (1)

where, I is the maximum current in ampere and dv/dt is the voltage scanning rate. The

areal capacitance was calculated using the relation,

퐶 퐶 = 푎 퐴 (2)

where ‘A’ is the area of active material dipped in the electrolyte. The specific capacitance Cs (Fg-1) of copper sulfide electrode was calculated using following relation,

퐶

Cs = 푊 (3)

where, W is the weight of copper sulfide electrode dipped in the electrolyte.

The specific capacitance (Cs) can be calculated as follows:

Itd C  s (4) VW

where I, Td, V and W denote current density, discharge time, potential range and active weight of the electrode material.

The energy density (E), power density (P) and coulombic efficiency (η) are calculated using

following equations respectively

VI t d d E  (5) W

VId P  (6) W

td  %  x 100 (7) tc

Where, ‘Id’ is discharge current, ‘td’ is the discharge time, ‘tc’ is charging time, ‘V’ is

potential window and W is the mass of active material within the electrode i.e. loaded mass

of the Cu:AMM and Cu:HMT electrodes.