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We first report the fabrication of all one dimensional (1D) active materials based Li-ion power packs using conversion type anode (α-Fe2O3). Electrospining procedure has been used to prepare all the 1D nanostructures. Half-cell studies are performed with metallic Li to ascertain the electrochemical activity of the individual components. In order to overcome irreversible capacity loss (ICL) in α-Fe2O3, the high voltage cathode has been over lithiated electrochemically (Li1.33Ni0.5Mn1.5O4) prior to the full-cell assembly. The combined advantages of 1D nanostructure and a new over lithiation concept certainly provides the less amount of active material loading to mitigate ICL. On the other hand, all based cell Li1.33Ni0.5Mn1.5O4/1 M LiPF6 gelled PVdF-HFP/α-Fe2O3 delivered an energy density of ∼193 Wh kg−1 with working potential of ∼3.27 V and rendered ∼88% of initial reversible capacity after 60 cycles.

The effect of processing history and morphology is of particular importance for lithium-ion electrolytes for achieving higher ionic conductivities. In this study, single ion conducting poly (4-lithium styrene sulfonic acid) was synthesized by neutralization reaction from polystyrene sulfonic acid, and the effect of morphology and processing method was studied by comparing pelletized, electrospun and gel samples. The PSSLi gels displayed best ionic conductivity, while the pelletized samples showed the worst ionic conductivity. Although electrospinning led to a free standing electrolyte, the lower amount of solvent phase led to lower ionic conductivity when compared to the PSSLi gel. The ionic conductivity at room temperature improved from 6.6 × 10−5 S/cm to 1.4 × 10−3 S/cm by optimizing the processing methodology and the lithium ion concentration. The results show that PSSLi based single ion conducting lithium (SICL) gels are a promising candidate for lithium ion battery application.

The effect of blending polyethylene oxide with poly (vinylidene fluoride)–lithium aluminum germanium phosphate (LAGP) composite and in-situ porosity generation on the electrochemical performance of polymer electrolytes based on non-woven fibrous mats is studied. Electrospinning process parameters are controlled to get a fibrous membrane consisting of bead-free, multilayered, three dimensional network structure of ultrafine fibers. The electrospun membranes are subjected to a preferential polymer dissolution process to prepare a highly porous structure. The membranes show high surface roughness with uniformly sized and distributed pores on the fibers. The membranes with good mechanical strength, thermal stability and high porosity exhibit high swelling when activated with liquid electrolyte. The prepared composite polymer electrolytes show high ionic conductivity. The addition of the glass ceramic improves the mechanical and thermal stability, while blending and in-situ porosity generation improves the ionic conductivity, charge–discharge performance, cycling stability, interface properties and compatibility with lithium electrode.

The advantageous properties of both solid soft matter electrolytes and polymer gel electrolytes (PGEs) are combined to develop a electrospun polymer composite electrolyte (PCE) for lithium ion batteries , based on addition of butanedinitrile (BDN, the plastic crystal) to poly(vinylidenefluoride- co -hexafluoropropylene) {P(VdF- co -HFP)} (semi crystalline polymer). Polymer composite electrolytes are prepared by activating the fibrous membrane with 1 M LiPF 6 in EC/DEC. The electrochemical characterization shows that the addition of BDN significantly improves the ionic conductivity of composite electrolytes even at lower temperatures due to the active role played by BDN in ion conduction. Also the compatibility of the polymer composite electrolyte with lithium electrode improves by incorporation of BDN. Galvanostatic cycling test demonstrates the suitability of these polymer composite electrolytes for lithium ion batteries in both Li/PCE/LiFePO 4 (half cell) and LTO/PCE/LiFePO 4 (full cell) configurations. The addition of BDN improves the charge discharge performance and cycling stability of the polymer composite electrolytes.

Effect of poly(ethylene oxide) on the electrochemical properties of polymer electrolyte based on electrospun, non-woven membrane of PVdF is demonstrated. Electrospinning process parameters are controlled to get a fibrous membrane consisting of bead-free, uniformly dispersed thin fibers with diameter in the range of 1.5–1.9 μm. The membrane with good mechanical strength and porosity exhibits high uptake when activated with the liquid electrolyte of lithium salt in a mixture of organic solvents. The polymer gel electrolyte shows ionic conductivity of 4.9 × 10−3 S cm−1 at room temperature. Electrochemical performance of the polymer gel electrolyte is evaluated in Li/polymer electrolyte/LiFePO4 coin cell. Good performance with low capacity fading on charge–discharge cycling is demonstrated.

Hybrid organic–inorganic polymer gel electrolytes (PGEs) based on polymer–clay nanocomposite microporous membrane containing 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate/diethyl carbonate (EC/DEC) are fabricated and their electrochemical characteristics in lithium ion batteries are studied. Poly(vinylidene fluoride) (PVdF)–clay nanocomposite membrane containing different clay loading are prepared by phase inversion method. Aqueous suspension of montmorrillonite (MMT) clay in dimethyl acetamide (DMAc) is used as the nano-clay. The morphology of the clay dispersion with sonication time is studied by environmental scanning electron microscope (E-SEM). The intercalation/exfoliation of polymer–clay nanocomposite is characterized by X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermal gravimetric analysis are used for the evaluation of thermal properties. DSC analysis shows that crystallinity of nanocomposite decreases with increasing nano-clay content. The effect of clay on the membrane morphology, ionic conductivity and electrochemical properties of the PGEs in lithium ion rechargeable batteries are studied and results are compared. Incorporation of 2 wt.% nano-clay in PGE enhances its ionic conductivity from 0.78 to 3.08 mS cm−1 at room temperature. Li-ion half cell comprising of Li/PVdF–clay(2 wt.%)-PGE/LiMn2O4 delivers high charge–discharge capacity (∼120 mAh g−1) and shows stable cycle performance.

A new approach for fabricating polymer gel electrolytes (PGEs) based on electrospun poly(vinylidenefluoride-co-hexafluoropropylene) {P(VdF-co-HFP)} incorporated with layered nanoclay has been employed to enhance the ionic conductivity and electrochemical properties of P(VdF-co-HFP) without compromising its mechanical strength. The effect of layered nanoclay on properties of membranes has been evaluated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Surface morphology of the membranes has been studied using field-emission scanning electron microscopy (FE-SEM). Polymer gel electrolytes are prepared by soaking the fibrous membrane into 1 M LiPF6 in EC/DEC. The electrochemical studies show that incorporation of layered nanoclay into the polymer matrix greatly enhanced the ionic conductivity and compatibility with lithium electrodes. The charge–discharge properties and cycling performance of Li/LiFePO4 cells comprising nanocomposite polymer gel electrolytes have been evaluated at room temperature.

One dimensional TiO2-B nanorods are synthesized by a conventional hydrothermal approach under highly concentrated alkali hydroxide solutions. Various characterization techniques such as X-ray diffraction, Raman studies, BET surface area measurements, scanning electron microscopy and transmission electron microscopy (TEM) are utilized. Electrochemical Li-insertion properties are evaluated by means of half-cell configuration (Li/TiO2-B) which delivered a discharge capacity of 195 mA h g−1 at a current density of 150 mA g−1 under ambient temperature conditions. The test cell, Li/TiO2-B, displayed good cycling profiles up to 500 cycles with columbic efficiency over 99.5%. Full-cell, LiMn2O4/TiO2-B, is fabricated and tested both in conventional liquid and PVdF-HFP membranes at a current density of 150 mA g−1 and exhibited an excellent cycleability up to 1000 cycles at an operating potential of ∼2.5 V. The results demonstrate the improved electrochemical performance and durability of one dimensional nanostructures i.e. TiO2-B nanorods and electrospun membranes during prolonged cycling. In addition, ex-situ TEM analysis revealed the retention of nanorod morphology along with the crystalline structure after 1000 cycles in full-cell assembly, which ensures excellent long-term cycleability of TiO2-B anodes.

We report for the first time the synthesis and extraordinary performance of a high voltage spinel LiNi(0.5)Mn(1.5)O4 fiber cathode in all one dimensional (1D) architecture. Structural and morphological features are analyzed by various characterization techniques. Li-insertion/extraction properties are evaluated in a half-cell assembly (Li/LiNi(0.5)Mn(1.5)O4) and subsequently in full-cell configuration with an anatase TiO2 fiber anode. In both half- and full-cell assemblies, gelled polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) is used as the separator-cum-electrolyte. All the one dimensional components used for fabricating Li-ion cells are prepared by a simple and scalable electrospinning technique. The full-cell, LiNi(0.5)Mn(1.5)O4/gelled PVdF-HFP/TiO2 delivered the reversible capacity of ∼ 102 mA h g(-1) at 0.1 C rate with an operating potential of ∼ 2.8 V. Excellent rate capability and stable cycling profiles are noted for such a full-cell assembly with a capacity retention of ∼ 86% after 400 cycles.

We successfully demonstrated the performance of novel, one-dimensional electrospun nanofibers as cathode, anode and separator-cum-electrolyte in full-cell Li-ion configuration. The cathode, LiMn2O4 delivered excellent cycle life over 800 cycles at current density of 150 mA g(-1) with capacity retention of ~93% in half-cell assembly (Li/LiMn2O4). Under the same current rate, the anode, anatase phase TiO2, rendered ~77% initial reversible capacity after 500 cycles in half-cell configuration (Li/TiO2). Gelled electrospun PVdF-HFP exhibits liquid-like conductivity of ~3.2 mS cm(-1) at ambient temperature conditions (30 °C). For the first time, a full-cell is fabricated with enitrely electrospun one-dimensional materials by adjusting the mass loading of cathode with respect to anode in the presence of gelled PVdF-HFP membrane as a separator-cum-electrolyte. Full-cell LiMn2O4|gelled PVdF-HFP|TiO2 delivered good capacity characteristics and excellent cyclability with an operating potential of ∼2.2 V at a current density of 150 mA g(-1). Under harsh conditions (16 C rate), the full-cell showed a very stable capacity behavior with good calendar life. This clearly showed that electrospinning is an efficient technique for producing high performance electro-active materials to fabricate a high performance Li-ion assembly for commercialization without compromising the eco-friendliness and raw material cost.

We report the construction and electrochemical performance of a high power Li-ion hybrid electrochemical capacitor (Li-HEC) using monoclinic TiO2-B nanorods as anodes with activated carbon cathodes. First, TiO2-B nanorods are synthesized by a conventional hydrothermal approach and a subsequent ion-exchange reaction with protons. Phase formation and morphological features are investigated through X-ray diffraction and scanning and transmission electron microscopy, respectively. Li-insertion properties are evaluated in half-cell configurations and reversible insertion of 0.52 moles of Li at a current density of 100 mA g−1 were found. The Li-HEC is constructed with optimized mass loading of the electrodes along with Whatman and electrospun PVdF–HFP membranes. Among them, electrospun PVdF–HFP comprising Li-HEC is found to be superior in terms of cyclability, higher energy and power densities. The electrospun PVdF–HFP comprising Li-HEC delivered the maximum energy and power densities of 23 W h kg−1 and 2.8 kW kg−1, respectively, with a capacitance retention of ∼73% after 1200 cycles at a current density of 1.5 A g−1.