M. Raja

Sisal-derived activated carbons for cost-effective lithium–sulfur batteries

Elemental sulfur was successfully impregnated in an activated carbon (AC) matrix obtained from sisal fibers. The impregnation of sulfur in the activated carbon (S-AC) matrix was confirmed by XRD, SEM and Raman analyses. The sulfurized activated carbon (S-AC) composite electrode was employed as a cathode material for lithium–sulfur (Li–S) cell. The Li–S cell delivered a discharge capacity of 950 mA h g−1 at 0.1C-rate. The electrochemical impedance spectroscopy measurements were carried out for the Li–S cell before and after cycling and also at different depth of discharge and depth of charge. A stable cycling was achieved at 1C-rate.

Metal organic framework-laden composite polymer electrolytes for efficient and durable all-solid-state-lithium batteries

A copper benzene dicarboxylate metal organic framework (Cu-BDC MOF) was synthesized and successfully incorporated in a poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI) complex. The incorporation of Cu-BDC MOF was found to significantly enhance the ionic conductivity, compatibility and thermal stability of the composite polymer electrolyte (CPE). An all-solid-state-lithium cell composed of Li/CPE/LiFePO4 was assembled, and its cycling profile has been analysed for different C-rates at 70 °C. The appreciable ionic conductivity, thermal stability and cycling ability qualify these membranes as electrolytes for all-solid-state-lithium batteries used in elevated temperature applications.

A flexible zirconium oxide based-ceramic membrane as a separator for lithium-ion batteries

A flexible and thermally stable zirconium oxide (ZrO2)-based porous ceramic membrane (PCM) was prepared with PVdF–HFP as binder. This membrane was found to have 60% porosity with good electrolyte uptake and appreciable Li+-ion transport number. TG analysis revealed that this membrane is thermally stable up to 400 °C. The ZrO2-based membrane exhibited better interfacial and electrochemical properties than the commercially available Celgard 2320 membrane. This ceramic membrane was employed as a separator in a 2032-type coin cell comprising Li/PCM/LiFePO4 and its charge–discharge profile was analyzed at different C-rates.

High performance multi-functional trilayer membranes as permselective separators for lithium–sulfur batteries

Multi-walled carbon nanotubes (MWCNTs) and magnesium aluminate (MgAl2O4) were coated on either side of a commercially available Celgard 2320 membrane by a simple doctor blade method. This trilayer membrane (TLM) was subjected to ionic conductivity, thermal stability and contact angle measurements. Each layer of the TLM functions for a specific purpose: the MWCNTs provide electronic conductivity while the pores of the Celgard 2320 membrane facilitate lithium-ion transport and MgAl2O4 suppresses the shuttling of polysulfides due to the electrostatic attractive force. The TLM exhibited superior thermal stability and ionic conductivity than the uncoated Celgard 2320 membrane. The Li–S cell with a TLM offered a higher discharge capacity than the one with an uncoated membrane. The results are compared with earlier reports.

Natural, biodegradable and flexible egg shell membranes as separators for lithium-ion batteries

Flexible egg shell membranes (ESM) were obtained from chicken eggs after treatment with hydrochloric acid. The ESMs were subjected to scanning electron microscopy (SEM) and thermogravimetric (TG) and wettability analyses. The morphological studies revealed that the membranes possessed uniform porosity and they were of micron size. The ESM was also found to be thermally stable above 230 °C. The electrochemical properties, such as ionic conductivity, lithium transport number (Lit+) and compatibility of the membrane upon activation in 1 M LiPF6 in EC : DMC (1 : 1 v/v), were analyzed. Finally, a 2032-type coin cell composed of Li/ESM/LiFePO4 was assembled and its cycling profile was also analyzed at different C-rates.

Enhanced cyclability using a polyindole modified cathode material for lithium sulphur batteries

Here we report a novel multiwall carbon nanotube/sulphur/polyindole (MWCNT/S/PIN) nanocomposite as a cathode material for lithium–sulphur (Li–S) batteries to alleviate capacity decay. The nanocomposite cathode material is synthesized by chemical precipitation of sulphur onto functionalized MWCNTs followed by in situ polymerization of indole. The MWCNT/S/PIN nanocomposite exhibits an initial specific capacity of 1490 mA h g−1 and enhanced cycling stability compared to the binary nanocomposite (MWCNT/S). The MWCNT/S/PIN composite cathode displays a specific capacity of 1043 mA h g−1 after 100 cycles at 0.1C rate with 70% capacity retention. The better electrochemical performance of the ternary nanocomposite cathode material is attributed to the synergistic effect of the functionalized MWCNTs and polyindole which provides an improved conductivity and effective fencing of intermediate polysulphides.

Polarization measurements and high spin structure in 131Ba

The high spin states of 131Ba have been populated in the fusion evaporation reaction 122Sn(13C,4n)131Ba at Ebeam = 65MeV. The γ transitions belonging to various band structures were detected using an array of fifteen Clover Germanium detectors. Some of new transitions have been placed in high spin states. Spin and parity for a band has been calculated for first time in 131Ba. The said band is interpreted in term of multi-quasiparticle configurations, based on Total Rothian Surfaces (TRS) calculations.