FULL PAPER 1805418 (1 of 14) © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.small-journal.com An Integrated Approach Toward Renewable Energy Storage Using Rechargeable Ag@Ni 0.67 Co 0.33 S-Based Hybrid Supercapacitors Goli Nagaraju, S. Chandra Sekhar, Bhimanaboina Ramulu, and Jae Su Yu* Dr. G. Nagaraju, S. C. Sekhar, B. Ramulu, Prof. J. S. Yu Department of Electronic Engineering Institute for Wearable Convergence Electronics Kyung Hee University 1732 Deogyeong-daero, Gihung-gu Yongin-si, Gyeonggi-do 17104, Republic of Korea E-mail: jsyu@khu.ac.kr Dr. G. Nagaraju Department of Chemical Engineering College of Engineering Kyung Hee University 1732 Deogyeong-daero, Gihung-gu Yongin-si, Gyeonggi-do 17104, Republic of Korea The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.201805418. DOI: 10.1002/smll.201805418 1. Introduction To fulfill alternative growing demands for portable electronic market as well as disquiets of rapid depletion of fossil fuels (such as coal, oil, and gas), research society has shifted its focus toward the development of sustainable energy harvesting and Self-powered charging systems in conjunction with renewable energy conversion and storage devices have attracted promising attention in recent years. In this work, a prolific approach to design a wind/solar-powered rechargeable high-energy density pouch-type hybrid supercapacitor (HSC) is proposed. The pouch-type HSC is fabricated by engineering nature-inspired nanosliver (nano-Ag) decorated Ni 0.67 Co 0.33 S forest-like nanostructures on Ni foam (nano-Ag@NCS FNs/Ni foam) as a battery-type electrode and porous activated carbon as a capacitive-type electrode. Initially, the core–shell- like NCS FNs/Ni foam is prepared via a single-step wet-chemical method, followed by a light-induced growth of nano-Ag onto it for enhancing the conductivity of the composite. Utilizing the synergistic effects of forest- like nano-Ag@NCS FNs/Ni foam as a composite electrode, the fabricated device shows a maximum capacitance of 1104.14 mF cm -2 at a current density of 5 mA cm -2 and it stores superior energy and power densities of 0.36 mWh cm -2 and 27.22 mW cm -2 , respectively along with good cycling stability, which are higher than most of previous reports. The high-energy storage capability of HSCs is further connected to wind fans and solar cells to harvest renewable energy. The wind/solar charged HSCs can effectively operate various electronic devices for a long time, enlightening its potency for the development of sustainable energy systems. Hybrid Supercapacitors storage devices. [1–4] Particularly, renewable energy sources (wind and solar), which can provide energy without greenhouse gas emission/air pollution, have attracted widespread attention for our long-term energy needs. [5–8] However, solar/wind- powered system is not complete without effective energy storage system, which leads to the rising search for perpetual storage devices. [9–11] Among various energy storage devices, supercapacitors (SCs) have attracted tremendous atten- tion owing to their desirable features of high-power density, quick charging ability, long-term durability, easy fabrication, and low cost. [12–14] Accordingly, they have been widely used in various electronic devices including military devices, plug-in electric vehicles, cold-start assistance, memory back-up sources, etc. [15–17] However, SCs impact on a major drawback of its low energy density, compared to lithium ion batteries that impede the wide applica- tions further. [18] As a next-generation energy storage device in the SC family, hybrid SCs (HSCs) have shown promising progress in exalting the energy density. The HSCs are composed of two distinct electrodes: battery- type electrode (e.g., Co 3 O 4 , NiO, ZnCo 2 O 4 , NiCo 2 S 4 , Ni 3 Se 2 , etc.) and electric-double layer capacitive electrode (EDLCs; graphene and porous activated carbon), which act as the energy and power sources, respectively. [19–23] The energy density of HSCs depends mainly on the electrochemical performance of electrode materials. [24–26] Generally, the battery-type materials showed rich redox reactions which occur at a specific potential. The redox chemistry can be enlarged based on the structural and morphological features of battery-type materials, which obviously results in the increment of capacity, thus leading to the enhancement in energy density of HSCs. [27–29] Meanwhile, the porous capacitive-type materials provide high-cycling dura- bility, owing to the electrosorption of ions on the surfaces of electrodes. [30] The fabricated HSC device sandwiched with the two electrodes can be expected to increase the energy density without fading its durability and power density. [31] Therefore, an extensive research is essential in developing versatile electrode materials to improve the performance of HSCs. [24,32] Of various battery-type materials, bimetallic chalcogenide- based nanostructures (such as NiCo 2 S 4 , Zn-Co-S, Ni 3 S 2 -MoS 2 , CuCo 2 S 4 , NiCoSe, etc.) with unconventional morphologies Small 2019, 1805418