The current work investigated two ionic-liquid (IL)-based deep eutectic solvents (DESs) composed of ethylene glycol (EG) and N-methylacetamide (NMAc) as hydrogen bond donors (HBD) and high-melting IL, namely, 1-butyl-3-methylimidazolium methanesulfonate ([BMIM]-[MeSO 3 ]), as the hydrogen bond acceptor (HBA). Initially, the COSMO-SAC model was employed for prediction of the eutectic points of the DESs. The computed melting points of the formulated DESs were found to be 70−100 °C lower than that of HBA. The viscosity of the newly developed DESs (∼15 cp) was significantly lower than that of neat room temperature IL electrolytes, and their ionic conductivity was found to be comparable to that of ILs. TGA study revealed no mass loss up to 90 °C, favoring the high temperature application of supercapacitors. To assess electrolytic performance in supercapacitors, electrochemical characterization was done using linear scan voltammetry (LSV), cyclic voltammetry (CV), and galvanostatic charge−discharge (GCD) techniques. LSV provided electrochemical stability up to 3.8 V against a glassy carbon electrode.[BMIM][MeSO 3 ] + EG and [BMIM][MeSO 3 ] + NMAc resulted in operating potential windows (OPWs) of 2 and 3 V, respectively, with a carbon electrode. Moderate values of specific capacitance (55−67 F g −1 ) and power (0.56−1.3 kW kg −1 ) were observed due to higher internal resistance. However, [BMIM][MeSO 3 ] + NMAc resulted in noteworthy specific energy (∼84 Wh kg −1 ) due to its wider OPW.

Lithium-rich layered cathodes have emerged as fascinating materials for high energy density lithium-ion cells owing to their high working voltage window and specific capacity. Herein, we report a novel high-capacity Lirich cathode material having the composition Li 1.17 Ni 0.34 Mn 0.5 O 2 synthesized through a simple carbonate co-precipitation method without using any chelating agents. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), Xray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) coupled with energy-dispersive spectroscopy (EDS) were employed to characterize the chemical composition, structure, morphology, and elemental distribution, respectively of the synthesized cathode material. The XRD results revealed a well-defined layered structure, and the SEM images show a porous structure, which is beneficial for electrolyte infiltration and easy lithium-ion diffusion. The material delivered an initial discharge capacity of 250.3 mAhg −1 at C/10 rate and exhibited excellent cycling stability (capacity retentions of >98% at C/10 and >90% at 1C rates at the end of 100 and 200 cycles, respectively). Rate capability studies show that the material delivers discharge capacities of 242.3 mAhg −1 at C/5, 220.1 mAhg −1 at C/2, 183.7 mAhg −1 at 1C, and 131.5 mAhg −1 at 2C rates. The excellent electrochemical performance of this cobalt-free high capacity Li-rich cathode material makes it a promising candidate for high energy density lithium-ion cells.

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Many strategies have been adapted to improve the stability of silicon (Si) based anodes, one of the widely studied methods is to make Si-graphene (SiÀ Gr) materials, all have adapted the sandwiched structure of SiÀ Gr or Si-graphene oxide (Si-GO) where Si nanoparticles (NP) are sandwiched between Gr based materials. Herein, we report a simple strategy to achieve SiÀ Gr based anode with a different structure than that of the intercalated structure, which is expected to provide better stability to the SiÀ Gr based anode, i. e. a core-shell structure. This core-shell structure based on a Si-nanographene oxide (Si-nGO) delivers an initial reversible specific capacity of ∼ 2000 mAhg À 1 and stability of � 250 cycles with 80% capacity retention at an active material (AM) AM mass loading of 1.5 mg cm À 2 , and at ∼ 2.0 mg cm À 2 , ∼ 160 cycles stability was achieved, which is one of the best reported values, meanwhile, intercalated Si-graphene oxide (Si-GO) exhibited only < 50 cycles stability at ∼ 2.0 mg cm À 2 mass loading. Higher current rate performance of Si-nGO was ∼ 70% retention of the initial capacity at 5 C, whereas Si-GO retention was < 25% at 5 C. Thus a change in the structure of SiÀ Gr based anode has improved the stability remarkably and shows that it is a promising strategy towards achieving electrode material for advanced lithium-ion batteries (LIBs).