Novel polymer electrolyte based on cob-web electrospun multi component polymer blend of polyacrylonitrile/poly(methyl methacrylate)/polystyrene for lithium ion batteries : preparation and electrochemical characterization

The aim of the present work is to prepare a novel polymer electrolyte (PE) based on multi component polymer blend of polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA) and polystyrene (PS) with varying compositions by electrospinning. Structural characterization is carried out using X-ray diffraction (XRD). The thermal and crystalline properties of the blend are studied by thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Morphology of the membrane is examined by field emission scanning electron microscope (FE-SEM). The voids and cavities generated by the interlaying of the fibers are effectively utilized for the preparation of PE by loading with lithium hexafluorophosphate (LiPF6) dissolved in ethylene carbonate (EC)/diethyl carbonate (DEC). The ionic conductivity of the polymer blend electrolyte is studied by varying the PMMA and PS content in the PAN matrix. The blend polymer electrolyte shows ionic conductivity of about 3.9 × 10(−3) S cm(−1). The performance evaluation in coin cells show good charge–discharge properties and stable cycle performance under the test conditions. The result shows that the prepared polymer blend electrolytes are promising materials for lithium ion batteries.Accepted versio

Electrochemical performance of NASICON type carbon coated LiTi2(PO4)3 with a spinel LiMn2O4 cathode

NASICON type LiTi2(PO4)3 particles are synthesized by a modified pechini type polymerizable complex method at 1000 °C in an air atmosphere. The synthesized LiTi2(PO4)3 particles are ball milled and subsequently carbon coated from the carbonization of glucose (C–LiTi2(PO4)3). Li-insertion properties are evaluated in half-cell configurations (Li/C–LiTi2(PO4)3) and delivered an initial discharge capacity of 117 mAh g−1 at a current density of 15 mA g−1. Carbon coating alleviates the severe capacity fading of LiTi2(PO4)3 during cycling. A full-cell with an operating potential of 1.5 V is constructed employing C–LiTi2(PO4)3 as the anode with a spinel cathode, LiMn2O4, which delivered the first discharge capacity of 103 mAh g−1 at current density of 150 mA g−1. The LiMn2O4/C–LiTi2(PO4)3 cell retains 72% of initial discharge capacity after 200 cycles and the results suggest that, the full-cell can be used for miniature applications by replacing other rechargeable systems like lead–acid, Ni–Cd and Ni–MH

High energy Li-ion capacitor and battery using graphitic carbon spheres as an insertion host from cooking oil

We report a facile low-temperature synthesis of graphitic carbons with a spherically shaped morphology (CO-CS) and high purity by the modified catalytic chemical vapour deposition using vegetable cooking oil as a carbon source. The excellent Li-insertion properties are noted with high reversibility (∼369 mA h g−1) in the half-cell assembly, which is very close to the theoretical capacity of graphite. Further explored the suitability to be used as an anode in the practical configurations, the intercalation type LiFePO4 and double layer forming activated carbon (AC) have been used as the cathodes toward the fabrication of Li-ion battery (LIB) and Li-ion capacitor (LIC), respectively. Prior to the LIC assembly, CO-CS has been pre-lithiated electrochemically. Both LiFePO4/CO-CS and AC/CO-CS assemblies display a maximum energy density of ∼337 and ∼108 W h kg−1 (based on an active material loading), respectively. The obtained values are better than those of the state-of-the-art LIB and LIC based on a graphitic anode. A decent cycle-ability is also registered for both cases.NRF (Natl Research Foundation, S’pore

High power lithium-ion hybrid electrochemical capacitors using spinel LiCrTiO4 as insertion electrode

We report the synthesis and electrochemical performance of sub-micron size LiCrTiO4 particles prepared by a solid-state approach. X-ray diffraction and transmission electron microscopic studies are used to analyze the structural and morphological properties, respectively, of the synthesized powders. Electrochemical Li-insertion properties are evaluated in half-cell configurations (Li/LiCrTiO4) by means of both galvanostatic and potentiostatic modes between 1 and 2.5 V vs. Li. Reversible insertion of almost one mole of lithium (155 mA h g−1) is noted at a low current rate of 15 mA g−1 and rendered an excellent cycling profile as well. A non-aqueous Li-ion electrochemical hybrid capacitor (Li-HEC) is fabricated with an optimized mass loading of activated carbon (AC) cathode and synthesized LiCrTiO4 as anode in 1 M LiPF6 in ethylene carbonate–diethyl carbonate solution and cycled between 1 and 3 V under ambient conditions. The Li-HEC delivered maximum specific energy and power densities of 23 W h kg−1 and 4 kW kg−1, respectively

LiCrTiO4 : a high-performance insertion anode for lithium-ion batteries

Bring on the power: A high-performance insertion-type LiCrTiO4 anode is synthesized by solid-state-reaction methods. Reversible insertion of almost one mole of lithium is achieved in the half-cell configuration. The picture shows a TEM image of LiCrTiO4 with superimposed cyclic voltammetric traces of a LiMn2O4/LiCrTiO4 cell

Electrochemical lithium insertion behavior of combustion synthesized V2O5 cathodes for lithium-ion batteries

Sub-micron size vanadium pentoxide (V2O5) particles are synthesized by novel urea assisted combustion method. Comprehensive characterization and electrochemical studies related to sintering temperature and duration are presented. X-ray diffraction (XRD) patterns showed the formation of pure-phase V2O5 and the surface morphologies are studied by field emission scanning electron microscopy (FE-SEM). Electrochemical properties of the sintered V2O5 as a cathode in lithium-ion batteries are explored with respect to synthesis parameters using cyclic voltammetry and galvanostatic charge-discharge studies. The V2O5 particles obtained from 600°C sintering temperature for 1 h exhibits a higher initial discharge capacity ∼320 mAh g−1 (∼2.2 Li per V2O5) between 1.75–4.0 V vs. Li/Li+ at 0.1 C rate and shows good capacity retention of >70% after 50 cycles. Electrochemical impedance spectroscopy (EIS) studies show that the urea combustion method enables increased Li+ ion diffusion pathways and electro-active surface area in V2O5 particles. Ball milling procedure with or without carbon is also adopted to further reduce the particle size of V2O5 and related electrochemical properties are evaluated and described.Published versio

Chemical lithiation studies on combustion synthesized V2O5 cathodes with full cell application for lithium ion batteries

Fundamental studies on Li-intercalation into layered vanadium pentoxide (V2O5), synthesized by urea combustion method, have been successfully carried out by chemical lithiation using butyl lithium at various concentrations. Morphological and structural changes during chemical lithiation are analyzed by field-emission scanning electron microscopy and X-ray diffraction measurements, respectively. Furthermore, chemical states and elemental concentration of these lithiated V2O5 phases were elucidated by X-ray photoelectron spectroscopy and inductively coupled plasma. Electrochemical studies via potentiostatic and galvanostatic modes show that the chemically-lithiated V2O5 phases undergo similar redox behavior as bare V2O5 at respective discharge-states. The electrochemical studies confirmed the occurrence of various phase transformations at various levels of discharge relating to both reduction of vanadium (V5+) and intercalation of lithium ions in V2O5. Finally, the full-cell comprising of lithiated V2O5 cathode and spinel Li4Ti5O12 anode is demonstrated to study their compatibility toward insertion type anodes, delivering the reversible capacity of 80 mAh g−1.Published versio

Improved elevated temperature performance of Al-intercalated V2O5 electrospun nanofibers for lithium-ion batteries

Al-inserted vanadium pentoxide (V2O5) nanofibers (Al-VNF) are synthesized by simple electrospinning technique. Powder X-ray diffraction (XRD) patterns confirm the formation of phase-pure structure. Elemental mapping and XPS studies are used to confirm chemical insertion of Al in VNF. Surface morphological features of as-spun and sintered fibers with Al-insertion are investigated by field emission scanning electron microscopy (FE-SEM). Electrochemical Li-insertion behavior of Al-VNFs are explored as cathode in half-cell configuration (vs. Li) using cyclic voltammetry and galvanostatic charge-discharge studies. Al-VNF (Al0.5V2O5) shows an initial discharge capacity of ~250 mAh g–1 and improved capacity retention of >60% after 50 cycles at 0.1 C rate, whereas native VNF showed only ~40% capacity retention at room temperature. Enhanced high current rate and elevated temperature performance of Al-VNF (Al1.0V2O5) is observed with improved capacity retention (~70%) characteristics. Improved performance of Al-inserted VNF is mainly attributed to the retention of fibrous morphology, apart from structural stabilization during electrochemical cycling.Accepted versio

From electrodes to electrodes : building high‐performance Li‐ion capacitors and batteries from spent lithium‐ion battery carbonaceous materials

We report the possibility of recycling carbonaceous materials (GC) from used/spent Li‐ion batteries (LIBs) and re‐using the material again as a negative electrode. In addition to LIB, the possibility of using them in Li‐ion capacitor (LIC) configuration with activated carbon is also explored. First, the carbonaceous materials are recovered from the mechanical treatment and subsequent leaching process. After the successful recovery, the Li‐insertion properties are studied in half‐cell assembly and it exhibits very decent electrochemical activity. While re‐using GC as an anode, large irreversibility is noted compared to fresh usage. Therefore, the elimination of such irreversible capacity is desperately required prior to the fabrication of either LIBs or LICs. Full‐cell LIB is assembled with olivine phase LiFePO4 cathode and the configuration delivers a maximum energy density of ∼313 Wh kg−1. Similarly, the GC is used as an anode in LIC assembly with commercial activated carbon. The LIC displays an energy density of ∼112 Wh kg−1 with decent cycling profiles.National Environmental Agency (NEA)Submitted/Accepted versionVA thank the financial support from Science & Engineering Research Board (SERB), a statutory body of the Department of Science & Technology, Govt. of India through Ramanujan Fellowship (SB/S2/RJN-088/2016). SM would like to thank the grant award from NEA (National Environmental agency) on Singapore – CEA Alliance for Research in Circular Economy (SCARCE), award number USS-IF-2018-4

Electrochemical route to alleviate irreversible capacity loss from conversion type α-Fe₂O₃ anodes by LiVPO₄F prelithiation

We report a new electrochemical procedure to suppress the irreversible capacity loss (ICL) from high capacity anodes, specifically for high capacity anodes that undergo either alloying or conversion reaction with Li. In the present work, tavorite type LiVPO₄F is used as Li-reservoir and conversion type α-Fe₂O₃ nanofibers as an anode. Unfortunately, LiVPO₄F cannot be used as the promising anode (∼1.7 V vs Li) because of its poor cycling stability, but it can be used to accommodate the desired amount of Li for ICL compensation. Accordingly, LiVPO₄F is electrochemically prelithiated (Li₁.₂₆VPO₄F) and paired with α-Fe₂O₃ nanofibers with optimized loadings. The full cell is displaying a maximum capacity of ∼755 mAh g⁻¹ (calculated on the basis of anode mass) with notable cycling profile. Before the fabrication of the full cell, half-cell studies are performed to assess the Li-storage capability at the same current rate for mass balance.Ministry of Education (MOE)National Research Foundation (NRF)This work was financially supported by Ministry of Education (MOE TIER 2 Funding (MOE2015-T2-1-046), Singapore and NTU-HUJ Create Phase II which is a joint research programme between the Hebrew University of Jerusalem (HUJ, Israel) and Nanyang Technological University (NTU, Singapore) with CREATE (Campus for Research Excellence and Technological Enterprise) funding from National Research Foundation of Singapore (NRF, SIngapore). V.A. acknowledges financial support from the Science & Engineering Research Board (SERB), a statutory body of the Department of Science & Technology, Government of India, through the Ramanujan Fellowship (SB/S2/RJN-088/2016)