The use of intrinsically conducting polymers (ICPs) like polythiophene (PTh), polypyrrole (PPy) and polyaniline (PANI) in devices and systems for electrochemical energy storage and conversion is ...briefly reviewed with a focus on an overview distinguishing between already established uses and potential applications. Basic principles in these three major fields are highlighted:•ICPs as active masses.•ICPs as conductance-enhancing additives.•ICPs as auxiliary materials beyond conductance.
A dense instead of porous gel polymer electrolyte for lithium ion batteries is reported for the first time. Its host is a renewable and environment friendly polymer, hydroxyethyl cellulose (HEC). The ...preparation of HEC membrane is very simple. The membrane is stable up to 280°C, much higher than the melting points of those commercial separators based on polyolefin. The evaporation temperature of the organic electrolyte in the prepared gel polymer electrolytes is up to 75°C. In addition, the gel polymer electrolyte shows good electrochemical performance including high ionic conductivity at room temperature, and a high lithium ion transference number. When tested as separator and electrolyte, a LiFePO4 positive electrode displays satisfactory electrochemical properties including high discharge capacity and stable cycling. These results indicate a very promising direction for a low cost and renewable gel polymer electrolyte for lithium ion batteries.
A dense instead of a porous gel polymer electrolyte with high transference number of Li+ ions and good safety. Display omitted
•A renewable and environment friendly cellulose is used to prepare gel polymer electrolyte.•The preparation process is simple.•The prepared polymer membrane is nonporous and dense instead of porous.•The prepared gel polymer electrolyte shows good electrochemical performance.
Since the birth of lithium ion battery in the end of 1980s and early 1990s many kinds of anode materials have been studied. Nevertheless, graphitic carbon is still the only commercially available ...product. As a result, modification of carbonaceous anode materials has been a research focus. In this paper, latest progress on carbon anode materials for lithium ion batteries is briefly reviewed including research on mild oxidation of graphite, formation of composites with metals and metal oxides, coating by polymers and other kinds of carbons, and carbon nanotubes. These modifications result in great advances; novel kinds of carbon anodes will come in the near future, which will propel the development of lithium ion batteries.
► Well entangled hybrids of MnO2 nanowires and MWCNTs are obtained by a facile method. ► Their electrochemical performance as cathode for supercapacitors in 0.5moll−1 Li2SO4 aqueous electrolyte is ...reported. ► The energy density (17.8Whkg−1) of the supercapacitor stays almost unchanged with power density from 400 to 3340Wkg−1. ► The energy density of the supercapacitor does not fade much after 13,000 cycles.
A hybrid of MnO2-nanowires and MWCNTs to be used as cathode in a supercapacitor with good electrochemical performance was prepared by a facile hydrothermal method. In this hybrid the α-MnO2 nanowires are well entangled with MWCNTs. The MWCNTs provide a network for fast electron transport whereas MnO2 nanowires show a fast redox response. Since gain/loss of both electrons and ions can be realized very rapidly at the same time, the hybrid has an excellent rate capability and delivers an energy density of 17.8Whkg−1 at 400Wkg−1, which is maintained almost constant even at 3340Wkg−1 in 0.5M Li2SO4 aqueous electrolyte. The cycling behavior is very good even in the presence of oxygen. The data present great promise for the hybrid as a practical cathode material for aqueous supercapacitor.
Ni-doped spinel LiNixMn2−xO4 (x=0, 0.05, 0.10) samples were prepared by a sol–gel method. Structure and morphology of the samples were characterized by X-ray diffraction, scanning electron ...microscopy, Brunnauer–Emmet–Teller method and inductively coupled plasma atomic absorption spectrometry. The electrochemical behavior as a cathode material (positive mass) for aqueous rechargeable lithium batteries (ARLBs) was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, capacity measurements and cycling tests. The results show that the LiNi0.1Mn1.9O4 electrode presents the best rate and cycling performance but low reversible capacity. In contrast, the LiNi0.05Mn1.95O4 electrode shows a higher reversible capacity and relatively good cycling behavior. At a current density of 150mAg−1, LiNi0.05Mn1.95O4 delivers a reversible capacity of 102mAhg−1. At the relative high current densities of 1500 and 3000mAg−1, the LiNi0.05Mn1.95O4 electrode still delivers reversible capacities of 95.0 and 88.7mAhg−1, respectively. The Ni-doped samples show excellent cycling life in 0.5molL−1 Li2SO4 aqueous solution. The capacity retention ratios for LiNi0.05Mn1.95O4 and LiNi0.10Mn1.90O4 after 800 cycles at a current density of 1500mAg−1 are 79.4% and 91.1%, respectively, much higher than that for the undoped LiMn2O4 at only 37.8%.
A LiMn2O4 nanohybrid consisting of nanotubes, nanorods and nanoparticles has been synthesized using I--MnO2 nanotubes from hydrothermal reaction as a precursor. It is characterized with X-ray ...diffraction, field emission scanning electron and transmission electron microscopy. A formation mechanism is proposed. As a positive electrode material for supercapacitors, it exhibits a high specific discharge capacitance of 415 F ga1 at 0.5 A ga1 in 0.5 mol la1 Li2SO4 aqueous solution. Even at 10 A ga1, it still has a specific discharge capacitance of 208 F ga1. The energy density of the asymmetric supercapacitor using activated carbon as the negative electrode and LiMn2O4-nanohybrid as the positive electrode in the aqueous solution in the voltage range of 0a1.8 V presents 29.8 Wh kga1 at power density of 90 W kga1. In addition, the cycling behavior of the asymmetric supercapacitor is good.
An eco-friendly water-based binder consisting of a combination of intrinsically conducting polymer poly-3,4-ethylenedioxythiopene:polystyrene sulfonate (PEDOT:PSS) dispersion and ...carboxymethylcellulose (СМС) proposed as component of Li4Ti5O12-based negative electrode has been studied at different compositions and compared with conventional PVDF binder. Morphology and structure of the composite materials were investigated by X-ray diffraction, scanning electron microscopy and EDX analysis. Electrochemical characterization was performed by galvanostatic charge-discharge experiments, cyclic voltammetry and impedance spectroscopy. The electrode with combined PEDOT:PSS/CMC binder has superior properties, in particular increased specific capacity and improved C-rate performance during charge-discharge. By using PEDOT:PSS/CMC binder instead of PVDF, the practical specific capacity was increased up to 14% (157 mAh g−1 at 0.2 C, normalized to total electrode mass). Highest stability during long cycling was observed for Li4Ti5O12-electrode with this binder at <1% decay after 100 cycles at 1 C. Electrochemical impedance spectra reveal a significant decrease of interfacial resistance and an increase of apparent diffusion coefficients for Li4Ti5O12 anode material with this binder, which supports improved functional characteristics of the electrode. As combined polyelectrolyte dispersion, the proposed conductive binder is an efficient alternative to the non-conductive PVDF binder for commercial lithium ion batteries.
•A water-based binder of poly-3,4-ethylenedioxythiopene:polystyrene sulfonate and carboxymethyl-cellulose (СМС) is proposed.•Electrode with combined PEDOT:PSS/CMC binder has superior properties: Icreased specific capacity and improved C-rate performance.•Used instead of PVDF the specific capacity is increased by up to 14%•Highest stability during long cycling was observed for Li4Ti5O12-electrode with this binder at less than 1% decay after 100 cycles at 1C.
Since the birth of the lithium ion battery in the early 1990s, its development has been very rapid and it has been widely applied as power source for a lot of light and high value electronics due to ...its significant advantages over traditional rechargeable battery systems. Recent research demonstrates the importance of surface structural features of electrode materials for their electrochemical performance, and in this paper the latest progress on this aspect is reviewed. Electrode materials are either anodic or cathodic ones. The former mainly include graphitic carbons, whose surfaces can be modified by mild oxidation, deposition of metals and metal oxides, coating with polymers and other kinds of carbons. Through these modifications, the surface structures of the graphitic carbon anodes are improved, and these improvements include: (1) smoothing the active edge surfaces by removing some reactive sites and/or defects on the graphite surface, (2) forming a dense oxide layer on the graphite surface, and (3) covering active edge structures on the graphite surface. Meanwhile, other accompanying changes occur: (1) production of nanochannels/micropores, (2) an increase in the electronic conductivity, (3) an inhibition of structural changes during cycling, (4) a reduction of the thickness of the SEI (solid-electrolyte-interface) layer, and (5) an increase in the number of host sites for lithium storage. As a result, the direct contact of graphite with the electrolyte solution is prevented, its surface reactivity with electrolytes, the decomposition of electrolytes, the co-intercalation of the solvated lithium ions and the charge-transfer resistance are decreased, and the movement of graphene sheets is inhibited. When the surfaces of cathode materials, mainly including LiCoO
2, LiNiO
2 and LiMn
2O
4, are coated with oxides such as MgO, Al
2O
3, ZnO, SnO
2, ZrO
2, Li
2O⋅2B
2O
3 glass and other electroactive oxides, the coating can prevent their direct contact with the electrolyte solution, suppress the phase transitions, improve the structural stability, and decrease the disorder of cations in the crystal sites. As a result, side reactions and the amount of the heat production during cycling are decreased. Simultaneously, other effects are observed such as: (1) suppression of the dissolution of Mn
2+, (2) higher conductivity, and (3) removal of HF from the electrolyte solution. Consequently, after the above-mentioned effective coating, marked improvements in the electrochemical performance of the electrode materials including the reversible capacity, the coulombic efficiency in the first cycle, the cycling behavior, and the high rate capability have been achieved. However, many surface science issues are still remaining open, e.g., mechanisms of these coatings and different actions of different coatings, and some further directions are suggested for the surface modification of the electrode materials.
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