Research and development activities on sodium-ion batteries are becoming prominent in the past few years. Compared to lithium-based batteries, the sodium-based batteries will be cheaper because of the abundancy of sodium raw materials in the earth’s crust and also in seawater. In the current study, we synthesized and characterized poly-acrylonitrile (PAN)-based gel-polymer electrolytes formed with NaClO4 and dissolved in ethylene carbonate (EC) and propylene carbonate (PC). By systematically varying the weight ratios of polymer, salt, and the solvents, we obtained an optimum room temperature ionic conductivity of 4.5 mS cm−1 for the composition 11PAN-12NaClO4-40EC-37PC (wt.%), which is reasonably good for practical applications. This value of conductivity is comparable to a few other Na+ ion conducting gel-polymer electrolyte systems studied in the recent past. Variation of ionic conductivity with inverse temperature showed Arrhenius behavior. Activation energies estimated for all the samples showed only a slight variation suggesting that a single activation process which depends on the EC/PC co-solvent governs the ionic mobility in these gel-polymer electrolytes. Thermo-gravimetric analysis (TGA) revealed that there is no noticeable weight loss of these electrolytes up to 100 °C and hence the electrolytes are thermally stable for operating temperatures up to 100 °C.

Cylindrical (type: 26650) Li-ion cells (LiFePO4 cathodes) currently used in the electric vehicles (EVs), plug-in hybrid electric vehicles etc. were subjected to simulated federal urban driving schedule at 25 and 50 degrees C for performance evaluation. Drive profiles (current versus time) for charge sustaining and charge depleting modes were derived from the federal urban driving schedule velocity profiles considering acceleration, regenerative braking, rolling resistance, drag force etc. for typical plug-in hybrid electric vehicles. In particular, the batteries were cycled extensively at 50 degrees C under charge sustaining as well as charge depleting modes to monitor capacity values, followed by analyzing the LiFePO4 cathode material by X-ray diffraction analysis. The capacity degradation was found to be very significant in both the modes with 13 and 19% under charge sustaining and charge depleting modes after 337 and 1007 cycles, respectively at elevated temperature. High frequency resistance values measured by electrochemical impedance spectroscopy were found to increase significantly under high temperature cycling, leading to power fading. As evident from Rietveld analysis, phase change in LiFePO4 is observed beyond 1000 cycles at elevated temperature under charge depleting mode, with the observation of FePO4 from the powder diffraction data of the cathodes from the cycled cells. In addition, there was also significant change in crystallite size of the cathode active materials after charge/discharge cycling under charge depleting mode. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The fuel economy of 31 MPG (based on combined city and highway) and Environment labels are being affixed to new vehicles after 2013 model year, as mandated by the U.S. Environmental Protection Agency. Most of the fuel-efficient 2016 model year passenger cars are hybrid electric vehicles. Hybrids combine the best features of the internal combustion engine with an electric motor powered by batteries and can significantly improve fuel economy. Plug-in hybrids are plugged into wall outlet for battery recharging or driven by electric motor for relatively longer distance. The all-electric vehicles are propelled by electric motor powered using rechargeable battery packs, emitting no tailpipe pollutants. Among various battery technologies, Li-ion battery system is the more preferable one for the automotive applications due to their relatively higher energy density. This review examines various aspects of Li-ion batteries related to performance, durability, energy management and safety related to automotive applications. The review also discusses about the possibility of automotive Li-Ion batteries towards second life in stationary applications.

Research and development efforts on sodium-ion batteries are gaining momentum due to their potential to accommodate high energy density coupled with relatively lower cost in comparison with lithium-ion batteries. In order for the sodium-ion batteries to be commercially viable, high performance electrolytes with acceptable ambient temperature ionic conductivity and wider electrochemical stability windows are being developed. A bibliometric analysis of the publications on various types of Na+ ion conducting electrolytes since 1990 shows a total of 200 + publications and reveals an exponential growth in the last few years, due to reasons that the sodium-ion systems promise great potential as the future large scale power sources for variety of applications. This review consolidates the status of liquid (non-aqueous, aqueous and ionic), polymer gel and solid (ceramics, glasses, and solid polymers) electrolytes and discusses their ionic conductivity, thermal characteristics, electrochemical stability and viscosity towards applications in sodium-ion batteries. Among various types available, the non-aqueous solvent based electrolyte is the most promising one in terms of ionic conductivity even though it is flammable. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.