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N-allyl-N-methylpiperidinium bis(trifuoromethansulfonyl)imide (PP13*TFSI) ionic liquid was adopted as a solute replacing partial of lithium salt in a concentrated propylene carbonate (PC) electrolyte. Varying the concentration of PP13*TFSI ionic liquid can change the electrolyte solution structure and thus optimize the solid electrolyte interphase (SEI) on the graphite anode. The number of PC molecules coordinated with lithium ion is significantly altered and this results in a change of the SEI mechanism at the electrode/electrolyte interface. At an optimum molar ratio of 2:1 between LiTFSI and PP13*TFSI, the first coulombic efficiency and the cycling capability of the graphite anode are significantly improved. Fourier transform infrared spectroscopy (FTIR) verified the SEI mechanism change from two-electron reduction to one-electron reduction in the presence of PP13*TFSI ionic liquid. SEM and TEM observations reveal a thin, homogenous and compact SEI film formed on the graphite surface in the 3 mol L−1 LiTFSI+PP13*TFSI(2:1)/PC concentrated electrolyte.

N-Methylacetamide (NMA) is used as an electrolyte component to suppress co-intercalation of propylene carbonate (PC) molecules into the graphite anode in lithium ion batteries. From the cyclic voltammetric and charge–discharge properties of graphite in a PC-based electrolyte containing an NMA component, it is found that the addition of the NMA solvent is effective in suppressing co-intercalation and irreversible decomposition of PC solvent. The graphite anode can be effectively cycled in the electrolyte and a first coulombic efficiency of 75.9% is obtained. SEM and EDX studies show that NMA participates in the formation of a solid electrolyte interphase (SEI), which is able to inhibit co-intercalation and irreversible reductive decomposition of PC molecules. Raman spectroscopic investigation reveals that the interaction between Li ions and PC is decreased because Li ions can be preferentially solvated by solvent NMA. When NMA is used as an additive in a PC–ethylene carbonate (EC) co-solvent electrolyte, a first coulombic efficiency of 87.6% is obtained, considerably higher than that of 51.6% obtained in the reference electrolyte. The cycling stability of the graphite electrode is also significantly improved in the NMA-added electrolyte.

Electrolytes play an essential role in determining the safety and electrochemical performance of Li-ion batteries. This work reported a propylene carbonate-based electrolyte with high-concentration Li salt. The fire-retardancy test and thermogravimetric analysis showed that this electrolyte is of high safety. In addition, this electrolyte exhibited superior electrochemical performance as compared with the commercial electrolyte in case of reversible capacity, rate behavior, and cycling stability.

A new symmetric aqueous rechargeable battery was assembled by utilizing NiFe2O4 hollow microspheres as electrode materials. In this device, the cathode and anode use the same material, but undergo respective redox reaction due to the well-separated redox pairs of NiFe2O4. This new battery possesses a high working voltage of 1.3 V and a capacity of 26 mAh g−1 based on the total mass of active materials. Keywords: Aqueous, Batteries, High voltage, Nickel ferrite

Hierarchical V2O5 microspheres composed of stacked platelets are fabricated through a facile, low-cost, and energy-saving approach. The preparation procedure involves a room-temperature precipitation of precursor microspheres in aqueous solution and subsequent calcination. Because of this unique structure, V2O5 microspheres manifest a high capacity (266 mA h g(-1)), excellent rate capability (223 mA h g(-1) at a current density 2400 mA g(-1)), and good cycling stability (200 mA h g(-1) after 100 cycles) as cathode materials for lithium-ion batteries.

The main bottlenecks restricting the development of Na-ion batteries are the inferior rate capability and cyclability of cathodes. In this work, a novel cathode material for Na-ion storage, namely, low crystallinity VOOH hollow microspheres, is prepared through a template-free hydrothermal route, and exhibits outstanding rate behavior and long life.