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Bioinspired pomegranate-like microflowers confining core-shell binary NiₓSy nanobeads for efficient supercapacitors exhibiting a durable lifespan exceeding 100 000 cycles

Yang, Cheng, Shi, Minjie, Tian, Yuyu, Yang, Jun, Song, Xuefeng, Zhao, Liping, Liu, Jing, Zhang, Peng, Gao, Lian
Journal of materials chemistry A 2019 v.7 no.7 pp. 3432-3442
capacitance, electrochemistry, electronics, energy density, graphene, nanoparticles, nickel, pomegranates, solar energy
Inspired by the structure of pomegranates, an intriguing pomegranate-like microflower (PM-NiₓSy) confining core–shell binary nickel sulfide (β-NiS/Ni₃S₄) nanobeads has been constructed for the first time, which contributes to breaking through the bottleneck of poor cycle performance for nickel sulfide-based supercapacitors (SCs). The PM-NiₓSy microflowers possess an open nano–micro-structure, in which the core–shell binary NiₓSy nanobeads are well confined in the compartment of three-dimensional (3D) graphene flowers, endowing them with robust structural integrity. Profiting from the unique structure, the PM-NiₓSy microflowers deliver a high specific capacity of 323.8 mA h g⁻¹ at 2 A g⁻¹ and maintain a capacity retention up to 98.9% even after 100 000 cycles. PM-NiₓSy//PG asymmetric supercapacitors (ASCs) are assembled and achieve an attractive energy density of 88 W h kg⁻¹ at a power density of 810 W kg⁻¹. More importantly, 97.6% of the initial capacitance is still retained even after 100 000 cycles at 5 A g⁻¹ for PM-NiₓSy//PG ASCs, displaying their unprecedented durable cycling life. On this basis, ASCs can be recharged by sustainable solar energy and repeatedly supply power to various electronics without a decline of electrochemical performance. Therefore, this work presents a facile route to design a pomegranate-like microflower for SCs with durable cycling performance that can be applied to store sustainable energy.