Synthesis of a NiMoO4/3D-rGO nanocomposite via starch medium precipitation method for supercapacitor performance

This paper presents research on the synergistic effects of nickel molybdate and reduced graphene oxide as a nanocomposite for further development of energy storage systems. An enhancement in the electrochemical performance of supercapacitor electrodes occurs by synthesizing highly porous structures and achieving more surface area. In this work, a chemical precipitation technique was used to synthesize the NiMoO4/3D-rGO nanocomposite in a starch media. Starch was used to develop the porosities of the nanostructure. A temperature of 350◦C was applied to transform graphene oxide sheets to reduced graphene oxide and remove the starch to obtain the NiMoO4/3D-rGO nanocomposite with porous structure. The X-ray diffraction pattern of the NiMoO4 nano particles indicated a monoclinic structure. Also, the scanning electron microscope observation showed that the NiMoO4 NPs were dispersed across the rGO sheets. The electrochemical results of the NiMoO4/3D-rGO electrode revealed that the incorporation of rGO sheets with NiMoO4 NPs increased the capacity of the nanocomposite. Therefore, a significant increase in the specific capacity of the electrode was observed with the NiMoO4/3D-rGO nanocomposite (450 Cg−1 or 900 Fg−1) when compared with bare NiMoO4 nanoparticles (350 Cg−1 or 700 Fg−1) at the current density of 1 A g−1. Our findings show that the incorporation of rGO and NiMoO4 NP redox reactions with a porous structure can benefit the future development of supercapacitors.

Synthesis of NiMoO4/3D-rGO Nanocomposite in Alkaline Environments for Supercapacitor Electrodes

Although Graphene oxide (GO)-based materials is known as a favorable candidate for supercapacitors, its conductivity needs to be increased. Therefore, this study aimed to investigate the performance of GO-based supercapicitor with new methods. In this work, an ammonia solution has been used to remove the oxygen functional groups of GO. In addition, a facile precipitation method was performed to synthesis a NiMoO4/3D-rGO electrode with purpose of using synergistic effects of rGO conductivity properties as well as NiMoO4 pseudocapacitive behavior. The phase structure, chemical bands and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), Raman spectroscopy, and field emission secondary electron microscopy (FE-SEM). The electrochemical results showed that the NiMoO4/3D-rGO(II) electrode, where ammonia has been used during the synthesis, has a capacitive performance of 932 Fg(-1). This is higher capacitance than NiMoO4/3D-rGO(I) without using ammonia. Furthermore, the NiMoO4/3D-rGO(II) electrode exhibited a power density of up to 17.5 kW kg(-1) and an energy density of 32.36 Wh kg(-1). These results showed that ammonia addition has increased the conductivity of rGO sheets, and thus it can be suggested as a new technique to improve the capacitance

Highly Stable Cycling of Silicon-Nanographite Aerogel-Based Anode for Lithium-Ion Batteries

Silicon anodes are considered as promising electrode materials for next-generation high-capacity lithium-ion batteries (LIBs). However, the capacity fading due to the large volume changes (∼300%) of silicon particles during the charge−discharge cycles is still a bottleneck. The volume changes of silicon lead to a fracture of the silicon particles, resulting in the recurrent formation of a solid electrolyte interface (SEI) layer, leading to poor capacity retention and short cycle life. Nanometer-scaled silicon particles are the favorable anode material to reduce some of the problems related to the volume changes, but problems related to SEI layer formation still need to be addressed. Herein, we address these issues by developing a composite anode material comprising silicon nanoparticles and nano graphite. The method developed is simple, cost-efficient, and based on an aerogel process. The electrodes produced by this aerogel fabrication route formed a stable SEI layer and showed high specific capacity and improved cyclability even at high current rates. The capacity retentions were 92 and 72% of the initial specific capacity at the 171st and the 500th cycle, respectively

Spent graphite from end-of-life Li-ion batteries as a potential electrode for aluminium ion battery

Graphite is central in almost all commercial Li-ion batteries (LIBs) and possesses attractive physical and chemical properties such as good ionic conductivity and layered graphitic structure. In this communication, we have demonstrated the recycling of graphite from end-of-life LIBs and the re-purposing of the recovered material for positive electrodes in next-generation aluminium-ion-batteries (AIBs). The recovered graphite possesses enlarged interlayer spacing which is shown to effectively boost Al-ion insertion/de-insertion during the charge/discharge processes. Excellent Al-ion storage performance is achieved with the capacity reaching 124 mAh g−1 at 50 mA g−1. The material retained a capacity of 55 mAh g−1 even after the applied current was increased to 500 mA g−1, showing its capability to deliver high rate performance. The charge/discharge cycling further revealed that the graphite retains 81% of its initial capacity even after 6700 cycles at a high rate of 300 mA g−1. This excellent aluminium ion storage performance makes the recovered graphite a promising positive electrode material, providing a possible solution for the recycling of huge amounts of LIB scrap. At the same time, this material aids the development of alternative sustainable battery technology, as an alternative to LIBs

Synthesis and Electrochemical Performance of Mesoporous NiMn2O4 Nanoparticles as an Anode for Lithium-Ion Battery

NiMn2O4 (NMO) is a good alternative anode material for lithium-ion battery (LIB) application, due to its superior electrochemical activity. Current research shows that synthesis of NMO via citric acid-based combustion method envisaged application in the LIB, due to its good reversibility and rate performance. Phase purity and crystallinity of the material is controlled by calcination at different temperatures, and its structural properties are investigated by X-ray diffraction (XRD). Composition and oxidation state of NMO are further investigated by X-ray photoelectron spectroscopy (XPS). For LIB application, lithiation delithiation potential and phase transformation of NMO are studied by cyclic voltammetry curve. As an anode material, initially, the average discharge capacity delivered by NMO is 983 mA center dot h/g at 0.1 A/g. In addition, the NMO electrode delivers an average discharge capacity of 223 mA center dot h/g after cell cycled at various current densities up to 10 A/g. These results show the potential applications of NMO electrodes for LIBs

Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries

To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films. However, a method that allows the large-scale production of silicon anodes remains to be demonstrated. Herein, we address this question by suggesting new scalable nanomaterial-based anodes. Si nanoparticles were grown on nanographite flakes by aerogel fabrication route from Si powder and nanographite mixture using polyvinyl alcohol (PVA). This silicon-nanographite aerogel electrode has stable specific capacity even at high current rates and exhibit good cyclic stability. The specific capacity is 455 mAh g−1 for 200th cycles with a coulombic efficiency of 97% at a current density 100 mA g−1