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We present the thermal evolution of two NASICON-type ceramics namely LATP (Li1+xAlxTi2−x(PO4)3) and LAGP (Li1+xAlxGe2−x(PO4)3) by monitoring the electrode–electrolyte interfaces (i.e., Li/LATP and Li/LAGP) at temperatures up to 330 °C via in situ scanning electron microscopy, post-mortem energy-dispersive spectroscopy, and X-ray diffraction. Upon melting of Li and contacting electrolytes, LAGP decomposes completely to form Li based alloys, while LATP is partially decomposed without alloying.

In this work, we deposited a nanometric layer of platinum (40 nm thick) on a standard propylene/polypropylene Celgard separator 3501 by plasma sputtering, and studied the effect of this thin layer when in contact with a lithium metal anode in a Li-S battery. The platinum-coated Celgard slowed down the shuttle effect at low current density (C/10) compared to standard Celgard and led to an increase in capacity retention at higher current density (C/2). In addition, the polarization was reduced with a platinum separator in a Li-Li symmetric cell after 500 h.

Organic cathode materials for lithium batteries are becoming increasingly popular because they have high theoretical redox voltage, high gravimetric capacity, low cost, easy processing and sustainability. However, their development is limited by their solubility in the electrolyte, which leads to rapid deterioration of the battery upon cycling. We developed a Janus membrane, which consists of two layers – a commercial polypropylene separator (Celgard) and a 300–600 nm layer of exfoliated graphite that was applied by a simple and environmentally friendly process. The submicron graphite layer is only permeable to Li+ and it drastically improves the battery performance, as measured by capacity retention and high coulombic efficiency, even at 2C rates. Post-mortem analysis of the battery indicates that the new membrane protects the anode against corrosion, and cathode dissolution is reduced. This graphite-based membrane is expected to greatly expedite the deployment of batteries with organic cathodes.

We report the effect of pressure on a membrane made of dense electrospun NASICON-like Li1.3Al0.3Ti1.7(PO4)3 (LATP). The properties and performance of the pressed LATP nanofibers were investigated and compared with those of pristine LATP nanofibers. While the applied pressure affects the purity and homogeneity of LATP, it is beneficial for ionic transport across the solid electrolyte. The presence of impurity phases as well as the decrease of porosity results in a two order of magnitude higher ionic conductivity at room temperature (3 × 10−5 S cm−1) which is promising to replace bulk NASICON materials in energy storage devices.

In situ X-ray diffraction was employed to investigate the crystal structure changes in Cr/Si co-doped Li(Co,Fe)PO4 cathode material during a galvanostatic charge/discharge process at a slow rate of C/30. The evolution of the X-ray patterns revealed that the phase transformation between the Cr/Si-Li(Co,Fe)PO4 and Cr/Si-(Co,Fe)PO4 is a two-step process, which involves the formation of an intermediate compound of Cr/Si-Li0.62(Co,Fe)PO4 upon the extraction of Li ions from the pristine phase. Different from the previously reported two biphasic transition steps, the phase transformation of the Cr/Si-Li(Co,Fe)PO4 followed a solid solution and a biphasic reaction pathway at different stages of the delithiation/lithiation process, respectively.

We report the synthesis of ceramic Li1.5Al0.5Ge1.5(PO4)3 (LAGP) nanofibers by combining sol–gel and electrospinning techniques. A homogeneous and stable precursor solution based on chlorides was achieved by controlling Ge hydrolysis. Subsequent electrospinning and heat treatment resulted in highly porous nanostructured NASICON pellets. After a full chemical-physical characterization, various amounts of LAGP nanofibers were used as a filler to develop polyethylene oxide (PEO)-based composite electrolytes. The addition of 10% LAGP nanofibers has allowed doubling the ionic conductivity of the plain polymer electrolyte, by providing longer ion-conductive paths and reducing PEO crystallinity. These findings are promising towards developing solution-based synthesis approaches featuring Ge precursors. In addition, the achieved LAGP nanofibers proved to be a promising nanofiller candidate to develop composite electrolytes for next-generation solid-state batteries.

Solid-state lithium metal batteries (SSLMBs) are promising next-generation high-energy rechargeable batteries. However, the practical energy densities of the reported SSLMBs have been significantly overstated due to the use of thick solid-state electrolytes, thick lithium (Li) anodes, and thin cathodes. Here, a high-performance NASICON-based SSLMB using a thin (60 um) Li1.5Al0.5Ge1.5(PO4)3 (LAGP) electrolyte, ultrathin (36 um) Li metal, and high-loading (8 mg cm-2) LiFePO4 (LFP) cathode is reported. The thin and dense LAGP electrolyte prepared by hot-pressing exhibits a high Li ionic conductivity of 1 x 10-3 S cm-1 at 80 C. The assembled SSLMB can thus deliver an increased areal capacity of 1 mAh cm-2 at C/5 with a high capacity retention of 96% after 50 cycles under 80 C. Furthermore, it is revealed by synchrotron X-ray absorption spectroscopy and in situ high-energy X-ray diffraction that the side reactions between LAGP electrolyte and LFP cathode are significantly suppressed, while rational surface protection is required for Ni-rich layered cathodes. This study provides valuable insights and guidelines for the development of high-energy SSLMBs towards practical conditions.

Recently many observations related to the catalytic effects of layered metal disulfide versus polysulfide electrochemistry were documented. In this work, we investigated the reactivity of layered WS2 in a Li-S battery and observed a chemical reaction involving the removal of W ions by polysulfides. The presence of metallic tungsten nanoparticles in the sulfur cathode is the result of W ion oxidation reaction and subsequent recrystallization during cycling. In situ Raman spectroscopy and ex situ transmission electron microscopy were used in order to clarify the reaction mechanism.

Lithium–sulfur batteries are of great interest owing to their high theoretical capacity of 1675 mA h g−1 and low cost. Their discharge mechanism is complicated and it is still a controversial issue. In the present work, in situ Raman spectroscopy is employed to investigate the poly-sulfide species in the sulfur cathode and in the electrolyte during the cycling of Li–S batteries. The aim is to understand the discharge mechanism and the influence of the electrolyte on the dissolution of sulfur and poly-sulfides. S8n− is identified as the main species in the high voltage plateau of discharge together with cycloocta S8, in the cell using 0.5 mol L−1 LiTFSI–PY13–FSI as the electrolyte. S42−, S22− and S2− are detected soon after the low voltage plateau is reached. A discharge mechanism in the PY13–FSI is proposed based on the identified species which provides important information for improving and designing cathodes. Electrolytes of 0.5 mol L−1 LiTFSI–PY13–FSI and 1 mol L−1 LiTFSI–DOL–DME are used in studying the dissolution of sulfur and poly-sulfides. The results demonstrate that the same poly-sulfide species are present in the two electrolytes. However, the rates of poly-sulfide formation and diffusion to the anode are slow in the ionic liquid compared to those in the ether-based electrolyte due to different ionic mobilities of various species in the two electrolytes. These differences are evidenced by the observation of poly-sulfide species in the DOL–DME from the very beginning of cell assembly even before starting the discharge whereas their appearances, in the ionic liquid, are delayed and only found at the end of the high voltage plateau. Notably, the soluble elemental sulfur is clearly observed in the ionic liquid electrolyte during the first discharge in the high voltage region, which is very different from the DOL–DME system where the elemental sulfur is quickly reduced to poly-sulfides due to self-discharge reactions. In addition, the elemental sulfur is also detected near the lithium anode in DOL–DME at the end of charge, for the first time to our knowledge, which suggests that the degradation of lithium metal is caused by the multiple reactions of the lithium metal surface with soluble poly-sulfides and/or elemental sulfur.

Sulfide-based ionic conductors are one of most attractive solid electrolyte candidates for all-solid-state batteries. In this review, recent progress of sulfide-based solid electrolytes is described from point of view of structure. In particular, lithium thio-phosphates such as Li7P3S11, Li10GeP2S12 and Li11Si2PS12 etc. exhibit extremely high ionic conductivity of over 10−2 S cm−1 at room temperature, even higher than those of commercial organic carbonate electrolytes. The relationship between structure and unprecedented high ionic conductivity is delineated; some potential drawbacks of these electrolytes are also outlined.

In this paper, we report the synthesis of cross-linked copolymers of glycidyl methacrylate (GMA) and poly (ethylene glycol) methyl methacrylate (PEGMA) for use as solid polymer electrolytes (SPE). The cross-linking is performed with volatile ethylene diamine, thus preventing the accumulation of undesirable precursors in the final membrane. The structure of the cross-linked polymer electrolyte was investigated by 13C solid NMR and its physical properties were examined by DSC, TGA and stress-strain tests. The ionic conductivities were determined by AC Impedance, which showed that the SPEs have good conductivities (10−5 Scm−1) at 80 °C. The highest capacity measured with these polymers was 151 mAh g−1 at C/6 and 80 °C for a LFP/SPE/Lithium battery. The retention capacity is high, at 97% after 80 cycles at different rates of cycling. The Young's modulus of the membranes is as high as 1 GPa. The SEM images showed no evidence of lithium dendrites and no degradation after cycling. Therefore, the polymer is a good candidate for battery operation over a long time. Especially important is the ability of this polymer to prevent growth of dendrites on the Li-metal electrode.

The main challenges facing rechargeable batteries today are: (1) increasing the electrode capacity; (2) prolonging the cycle life; (3) enhancing the rate performance and (4) insuring their safety. Significant efforts have been devoted to improve the present electrode materials as well as to develop and design new high performance electrodes. All of the efforts are based on the understanding of the materials, their working mechanisms, the impact of the structure and reaction mechanism on electrochemical performance. Various operando/in-situ methods are applied in studying rechargeable batteries to gain a better understanding of the crystal structure of the electrode materials and their behaviors during charge-discharge under various conditions. In the present review, we focus on applying operando X-ray techniques to investigate electrode materials, including the working mechanisms of different structured materials, the effect of size, cycling rate and temperature on the reaction mechanisms, the thermal stability of the electrodes, the degradation mechanism and the optimization of material synthesis. We demonstrate the importance of using operando/in-situ XRD and its combination with other techniques in examining the microstructural changes of the electrodes under various operating conditions, in both macro and atomic-scales. These results reveal the working and the degradation mechanisms of the electrodes and the possible side reactions involved, which are essential for improving the present materials and developing new materials for high performance and long cycle life batteries.

Lithium/solid polymer electrolyte (SPE)/sulfur cells were studied in operando by two techniques: Scanning Electron Microscope (SEM) and ultraviolet–visible absorption spectroscopy (UV–vis). During the operation of the cell, extensive polysulfide dissolution in the solid polymer electrolyte (cross-linked polyethylene oxide) leads to the formation of a catholyte. A clear micrograph of the thick passivation layer on the sulfur-rich anode and the decreased SPE thickness by cycling confirmed the failure mechanism; the capacity decays by reducing the amount of active material, and by contributing to a charge inhibiting mechanism called polysulfide shuttle. The formation of elemental sulfur is clearly visible in real time during the charge process beyond 2.3 V. The non-destructive in operando UV–vis study also shows the presence of characteristic absorption peaks evolving with cycling, demonstrating the accumulation of various polysulfide species, and the predominant formation of S42− and of S62− during discharge and charge, respectively. This finding implies that the charge and discharge reactions are not completely reversible and proceed along different pathways.

With the advances in characterization techniques, various operando/in-situ methods were applied in studying rechargeable batteries in order to improve the electrochemical properties of electrode materials, prolonging the battery life and developing new battery materials. In the present review, we focus on the characterization of electrode materials with operando/in-situ X-ray diffraction and Raman spectroscopies. By correlating the results obtained via these two techniques in different electrode chemistry: (a) intercalation materials, such as layered metal oxides and (b) conversion materials, such as elemental sulfur. We demonstrate the importance of using operando/in-situ techniques in examining the microstructural changes of the electrodes under various operating conditions, in both macro and micro-scales. These techniques also reveal the working and the degradation mechanisms of the electrodes and the possible side reactions involved. The comprehension of these mechanisms is fundamental for ameliorating the electrode materials, enhancing the battery performance and lengthening its cycling life.

The battery energy-storage industry is evolving rapidly so new battery components are needed with high stability and improved energy density, as well as enhanced safety. In this paper, results on new salts, safer degradation and good electrochemical performances are reported. Four organic anions for Li-salts were synthesized and their conductivity, viscosity and electrochemical potential window in EC/DEC (3/7) solutions were examined. These salts have high thermal stability and safer degradation products (compared to LiPF6 and Li-TFSI), which were identified by TGA-MS. Cyclic voltammetry measurements showed their electrochemical window and oxidation limits were at least 4.3 and 4.5 V vs Li/Li+ using a platinum and high surface area carbon material working electrode, respectively. The salts passivated the common aluminum current collector at 4.4 V vs Li/Li+ and without corrosion. The properties of one Li salts were evaluated in half cell configuration as a model system using lithium iron phosphate (LFP), lithium titanate oxide (LTO) and graphite as electrodes. The performance of the salt showed promising behavior in the model system, compared to benchmark salts such as LiPF6 and Li-TFSI.

We report results obtained with lithium 4,5-dicyano-2-(trifluoromethyl) imidazolide (LiTDI), which we believe is a promising lithium salt for electrolytes in lithium-ion batteries. This “Huckel”- type salt has high charge delocalizations which contribute to good lithium-ion dissociation. In addition, it has high thermal stability and safer degradation products compared to LiPF 6 , which were identified by TGA-MS. It also does not corrode but passivate the aluminum current collector. Cyclic voltammetry measurements showed a stability up to 4.5 V, which is sufficient for use with standard cathode materials. The power capability of half cells containing LiTDI in EC/DEC was evaluated with standard cathodes used in lithium-ion batteries: LFP, NMC, LCO and LMO. Two LiTDI concentrations were investigated: 1 M and 0.6 M and compared with a reference electrolyte: 1 M LiPF 6 . In spite of a slightly lower conductivity than the LiPF 6 , LiTDI (1 M and 0.6 M) shows similar power capability up to 2C with LFP (84% of specific capacity recovered), 10C with NMC (61% of specific capacity recovered), and up to 20C for LMO (88% of specific capacity recovered). Furthermore, better power capability was obtained with 0.6 M LiTDI with LCO, which yielded 82% of specific capacity recovered at 1C (67% for 1 M LiTDI and 1 M LiPF 6 ).

In this paper we report on the synthesis of comb-like copolymers as solid polymer electrolytes (SPE). The synthesis involved anionic polymerization of styrene (St) and 4-vinylanisole (VA) as the followed by grafting of poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) by Atom Transfer Radical Polymerization (ATRP). The comb-like copolymer's structure was analyzed by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The membranes were made by solvent casting and the morphologies were analyzed by atomic forces microscopy (AFM) and scanning electron microscopy (SEM). We observed that a nano and micro phase separation occurs which improves ionic conductivity. The ionic conductivities were determined by AC Impedance, which showed that the SPEs have good conductivities (10−5 Scm−1) at room temperature owing to the negligible values (

The effects of moisture contamination in the Li-O2 battery system were investigated by comparing the electrochemical performance and post-mortem analysis of batteries prepared under different atmospheres: sealed container in an ambient atmosphere vs. sealed container in a dry-room or in a glove-box. The performance of the cells strongly depended on the atmosphere; furthermore it was found that the performance degradation of the Li metal anode comes from moisture contamination from the feed lines. In an ambient atmosphere, the cells showed higher 1st discharge capacity, higher impedance and significant increase of the cell weight owing to contamination of the oxygen by moisture. Post-mortem analysis revealed that the deterioration of lithium metal anode leads to the cell failure mechanism, and this comes from the moisture contamination. It was found that the performance of Li-O2 batteries is very sensitive to even traces of moisture contamination and every single part of the cell design including the choice of fitting parts and water permeability of the fitting material should be verified in order to obtain credible and reproducible results. This finding supports the idea that protection of the lithium metal electrode is indispensable to realize the practical application of Li-O2 or Li-air batteries.

It is widely believed that Li2S2 is one of the intermediate products of lithium–sulfur (Li–S) batteries. However, contradicting proposals regarding the role and even the existence of Li2S2 in Li–S batteries persist. To address this, we have carried out first principles calculations of the energetic and electronic properties of Li2S2 based on the most promising structures found through an evolutionary algorithmic study. Our proposed Li2S2 structure(s) give a discharge voltage of 2.11 V for 2Li+ + 2e− + Li2S2 → 2Li2S, which matches the lower plateau of the experimental discharge profile of Li–S cells. Our results also show that Li2S2 is subject to spontaneous disproportionation. Together these results indicate that Li2S2 plays a key intermediate non-equilibrium role in the discharge of Li–S batteries.

Recently, intensive efforts are dedicated to convert and store the solar energy in a single device. Herein, dye-synthesized solar cell technology is combined with lithium-ion materials to investigate light-assisted battery charging. In particular we report the direct photo-oxidation of lithium iron phosphate nanocrystals in the presence of a dye as a hybrid photo-cathode in a two-electrode system, with lithium metal as anode and lithium hexafluorophosphate in carbonate-based electrolyte; a configuration corresponding to lithium ion battery charging. Dye-sensitization generates electron–hole pairs with the holes aiding the delithiation of lithium iron phosphate at the cathode and electrons utilized in the formation of a solid electrolyte interface at the anode via oxygen reduction. Lithium iron phosphate acts effectively as a reversible redox agent for the regeneration of the dye. Our findings provide possibilities in advancing the design principles for photo-rechargeable lithium ion batteries., Photo-rechargable energy storage cells can provide plug-free power for various applications. Here the authors integrate a photo-absorbing dye complex with LiFePO4 nanocrystals as a lithium-ion battery cathode in a two-electrode system demonstrating its photo-charging and galvanostatic discharging.

Well-known since the 18th century and widely used in painting and later in photography, hexacyanoferrate, or “Prussian blue”, is currently getting its “second life” as a promising material in several of the most advanced fields of the present technological sectors. This is mostly due to the rapid development of the energy storage market, which requires advanced, reliable, but also cost-effective materials for large-scale applications in load-levelling of renewable energy power sources. Non-Li technologies are considered as one of the most fertile R&D directions in this field, and Prussian blue demonstrates extremely promising characteristics for this kind of application. The unique features of this material are due to peculiarities of its atomic structure and ionic and electronic properties. In this article we review and discuss current research efforts in this field employing different hexacyanoferrate-based compounds as potential electrochemical storage and electrochromic devices. After a brief review of its history, we analyze the peculiarities of the atomic structure of these types of systems. We further summarize and analyze the most important and interesting experimental electrochemical data in this field, linking the particular atomic structure of the studied compounds with their observed electrochemical behaviour. This provides us with a snapshot of the current experimental state in this field and allows us to make certain predictions for its future development.

A non-aqueous zinc–polyaniline secondary battery was fabricated with polyaniline Emeraldine base as cathode and zinc metal as anode in an electrolyte consisting of 0.3 M zinc-bis(trifluoromethyl-sulfonyl)imide Zn(TFSI) 2 dissolved in propylene carbonate. We observed that the formation of the battery required a prerequisite condition to stabilize the interfaces in order to maintain a stable capacity. The battery suffered from Zn dissolution which induces a competition between concurrent Zn dissolution and plating when the battery is in charge mode, and thus inefficient cycles are obtained. The capacity and coulombic efficiency of the battery depends on the charge–discharge rates. We propose cycling protocols at different rates to determine the steady-state rates of competing reactions. When the cell is cycled at ≥1 C rate, the coulombic efficiency improves. The maximum capacity and energy densities of the battery are 148 mAhg −1 and 127 mWhg −1 , respectively for discharge at C/2. The battery was successively charged/discharged at constant current densities (1C rate), and high cycling stability was obtained for more than 1700 cycles at 99.8% efficiency. Zinc dissolution and self discharge of the battery were investigated after 24 h of standby. The investigation showed that the battery experiences a severe self-discharge of 48% per day.

In this work, we analyzed the thermal stability of polycarbonate: lithium trifluoromethane sulphonylimide (LiTFSI) systems. Polyethylene carbonate (PEC) and polypropylene carbonate (PPC) undergo depolymerization to ethylene carbonate (EC) and propylene carbonate (PC), respectively, in the presence of Li salt under annealing treatment. The decomposition reaction can explain the surprising high ionic conductivity recently reported for solid polymer electrolyte (SPE) polycarbonate-based systems. Because this phenomenon can strongly impact the results of SPE research, it is essential to control the depolymerization of polymers to avoid inaccurate electrochemical performance. In addition, we observed that the standard drying procedure for the preparation of high-salt-concentration polymer (polymer-in-salt) SPEs traps a high amount of residual solvent, e.g., acetonitrile (ACN), due to the strong bond between the solvent and ionic species. This finding represents another factor influencing the remarkably high ionic conductivity.

The robustness of conductive networks and the accessibility of electrolyte into the network are important factors in designing the cathode electrode for lithium/sulfur (Li/S) batteries containing liquid electrolytes that involve liquid phase electrochemical reactions. We show that the performance of Li/S cells can be significantly improved by simply optimizing the electrode processing conditions to have open pore structures and mechanical integrity of the electrode architecture. It is demonstrated that the capacity of 1000 mAh g −1 at 0.1 C and the stable capacity retention of >700 mAh g −1 after 200 cycles at 0.5 C can be achieved with relatively high sulfur content of 68%. 417 Wh kg −1 in specific energy and 623 Wh l −1 in energy density are achievable with this new technology.

LiFePO4(LFP)-coated sulfur (S-LFP) particles were synthesized using a dry mechano-fusion method and electrochemically tested in a liquid electrolyte. This synthesis process (encapsulation) is completed in a few minutes without a solvent drying step, thus it is easily scalable for volume production. The S-LFP cathode showed an initial capacity of 1200 mAh/g at 0.1 C, and 80% capacity retention after 90 cycles at 0.5 C. 417 Wh/kg in specific energy and 623 Wh/l in energy density are achievable with this new technology. The results suggest that the LFP layer enhances the utilization of active sulfur and lowers the polarization for oxidation of Li2S2/Li2S. Keywords: Lithium/sulfur battery, Core–shell composite, LiFePO4, Mechano-fusion, Encapsulation

In this chapter, we describe the basic concept of intercalation applied to electrode materials for batteries. This phenomenon has attracted considerable attention in electrochemistry because of the use of intercalation compounds (ICs) as ion and electron exchangers in energy storage and conversion devices. The need for more efficient electrical energy storage devices has prompted research on new electrode materials. In lithium-ion batteries, positive and negative electrodes are ICs with electronic and ionic properties. The different classes of mechanism that controls the electrochemical reactions in galvanic cells are presented and the relationship structure-energy is examined.

The carbon-coated LiFePO4 Li-ion oxide cathode was studied for its electrochemical, thermal, and safety performance. This electrode exhibited a reversible capacity corresponding to more than 89 % of the theoretical capacity when cycled between 2.5 and 4.0 V. Cylindrical 18650 cells with carbon-coated LiFePO4 also showed good capacity retention at higher discharge rates up to 5C rate with 99.3 % coulombic efficiency, implying that the carbon coating improves the electronic conductivity. Hybrid pulse power characterization (HPPC) test performed on LiFePO4 18650 cell indicated the suitability of this carbon-coated LiFePO4 for high power HEV applications. The heat generation during charge and discharge at 0.5C rate, studied using an isothermal microcalorimeter (IMC), indicated cell temperature is maintained in near ambient conditions in the absence of external cooling. Thermal studies were also investigated by Differential Scanning Calorimeter (DSC) and Accelerating Rate Calorimeter (ARC), which showed that LiFePO4 is safer, upon thermal and electrochemical abuse, than the commonly used lithium metal oxide cathodes with layered and spinel structures. Safety tests, such as nail penetration and crush test, were performed on LiFePO4 and LiCoO2 cathode based cells, to investigate on the safety hazards of the cells upon severe physical abuse and damage.

Numerous layered structured compounds are interesting materials in which lithium intercalation occurs primarily without destruction of the host lattice. In many cases a rigid band model is a useful first approximation for describing the changes in electronic properties of the host material with intercalation. We observed, nevertheless, that the rigid-band model is not applicable to all of the layered compounds. One may argue that the applicability of the rigid-band model may be taken as a test for the properties most desirable in a good intercalation material. This needs yet to be more extensively documented for their promising applications as insertion electrode in rechargeable lithium batteries. This chapter presents the applicability of the rigid-band model on intercalation compounds with a layered structure namely the transition-metal chalcogenides MX 2 (X = S, Se) and the transition-metal oxides LiMO2 (M = Co, Ni) as well.

While lithium-ion batteries are currently the workhorses of portable electronics and power tools, the technology is just beginning to move up for power density applications such as electric drive vehicles and future energy storage options such as smart grids and back-up power systems. The later requires much higher charge rates that can be achieved to some extend by the use of nanomaterials. Two main reasons for electrochemical improvement are commonly evoked by designing electrode materials into the nanoscale domain: (1) the shorter diffusion lengths for the lithium ion across the active particle and (2) the increasing contact area between electrode and electrolyte. The purpose of this chapter is to draw attention to the technologies involved in the synthesis, layout and optimization of nano materials used as active components in Li-ion batteries. We present several nanostructured compounds such as lamellar compounds, manganese oxides and iron phosphates. Functional nanomaterials are also examined such are nanofibers, nanorods, nanocomposites, and nanocrystals.

The relationships between structural and electrochemical properties are examined for materials having three-dimensional (3D) structure for the diffusion paths for Li+ ions. Among the 3D lithium insertion compounds with M = manganese and vanadium cations, namely, binary M x O y and ternary LiM x O y phases are the most popular. A special emphasis to the different forms of spinel structures that are normal-spinel, defect-spinel, and doped-spinel frameworks are currently used as positive electrodes in high-power batteries for EVs.

Major challenges of the twenty-first century will concern the global climate change and dwindling fossil energy reserves that motivate to develop sustainable solutions based on renewable sources of energy. Because they are intermittent systems, accumulators of electric power are required. This chapter provides basic concept for the energy storage and conversion systems. Basic elements of technologies are also given, which make an introduction of the topics.

In this chapter, we present the progress that allows several lithium-intercalation compounds to become the active cathode element of a new generation of Li-ion batteries, namely the materials with a poly-anion-based structure M x (XO4) y (M is a transition-metal cation and X = P, S), which are promising to improve the technology of energy storage and electric transportation, and address the replacement of gasoline engine by meeting the increasing demand for green energy power sources. The electrode materials considered here are fluorine-containing compounds including fluorophosphates LiMPO4F (M = V, Fe, T), Li2 M′PO4F (M = Fe, Co, Ni), hybrid ion Li x Na1−x VPO4F, and fluorosulfates LiMSO4F; M = Fe, Co, Ni, Mn, Zn, Mg). The electrochemical performance of these materials as the active cathode element of Li-ion batteries is also discussed.

As we have seen in different chapters of this book, the electrodes are usually tested from half-cells consisting of lithium metal as the counter-electrode. This is a convenient tool to determine the irreversible capacity loss during the first and eventually the second cycle, the reversible capacity at available at different rates, the operating voltage. The properties of the full cell can then be anticipated from these data. The design of the batteries is dictated by different parameters that are reviewed in this chapter. The first one is the compatibility between the materials that are chosen for the two electrodes, according to the rules concerning the relative positions of their chemical potentials. We have detailed and explained these rules in Chap. 2, so we start here with electrodes which satisfy these compatibility rules allowing for the formation of a protective solid-electrolyte interface (SEI) layer at the surface of the negative electrode. The second most important parameter concerns the capacity of the electrodes.

The active elements for negative (anode) electrodes are reviewed here according to the following sequence. First, the carbon anode is considered, since almost all the Li-ion batteries on the market are presently equipped with graphitic carbon. Then the next elements of the Mendeleev table (Si, Ge, …) are considered. Then the metal oxides have been divided according to the three different Li insertion processes that determines their advantages and disadvantages: intercalation, alloying/de-alloying, conversion reaction. Only the promising elements for the next generations of Li-ion batteries have been selected. Emphasis is made on the progress achieved the last 5 years, since the reader is guided to other reviews for elder works.

The current commercial Li-ion batteries are based on organic liquids, i.e., ethyl carbonates that have a high dielectric constant and thus are good solvents for salts. They also show a fairly large electrochemical window of stability. However, these organic solvents have high vapor pressures and in case of accidental battery shorts or thermal runaway, can lead to fires and explosions. The objective of the present chapter is to summarize the state of the art of nonaqueous electrolytes with development on control the SEI formation, safety concerns with Li salts, protection against overcharge and fire retardants.

This chapter is devoted to the role of layered structured materials, since they have peculiar properties of mixed conduction for electrons and ions, so that redox reaction can be delocalized in their volume, so that they can be used as active materials of electrodes. We present the relationship between structure and electrochemical features with special attention for materials currently used as positive electrode in lithium batteries for their high capability to host foreign ions. Different crystal chemistries are examined from the basic lithiated metal dioxides structure to the very sophisticated solid solutions or composites.

Polyanionic compounds have emerged as novel lithium insertion compounds and considered as the most advanced positive electrodes for the next generation of Li-ion batteries owing to their advantages with regard to low cost, non-toxicity, environmental friendliness, and high safety. From the safety view point, compared to metal-oxide cathodes, these materials rank number one, with a remarkable thermal stability and tolerance to overcharge and over-discharge. This chapter outlines the structural, physical, and electrochemical properties of lithium-phosphate compounds. Several aspects that are important for applications are discussed such as morphology upon synthesis, residual impurities and surface state of particles. These impurities are identified and a quantitative estimate of their concentrations is deduced from the combination of analytical methods. LiFePO4 has won the challenge to be the active element for the positive electrode of Li-ion batteries for electro-mobility. An optimized preparation provides materials with carbon-coated particles free of any impurity phase, insuring structural stability and electrochemical performance that justify the use of this material as a cathode element in new generation of lithium secondary batteries operating for powering hybrid electric vehicles and full electric vehicles.

Physical and electrochemical characteristics of Li-ion battery systems based on LiFePO4 cathodes and graphite anodes with mixture electrolytes were investigated. The mixed electrolytes are based on an ionic liquid (IL), and organic solvents used in commercial batteries. We investigated a range of compositions to determine an optimum conductivity and non-flammability of the mixed electrolyte. This led us to examine mixtures of ILs with the organic electrolyte usually employed in commercial Li-ion batteries, i.e., ethylene carbonate (EC) and diethylene carbonate (DEC). The IL electrolyte consisted of (trifluoromethyl sulfonylimide) (TFSI) as anion and 1-ethyl-3-methyleimidazolium (EMI) as the cation. The physical and electrochemical properties of some of these mixtures showed an improvement characteristics compared to the constituents alone. The safety was improved with electrolyte mixtures; when IL content in the mixture is ≥40%, no flammability is observed. A stable SEI layer was obtained on the MCMB graphite anode in these mixed electrolytes, which is not obtained with IL containing the TFSI-anion. The high-rate capability of LiFePO4 is similar in the organic electrolyte and the mixture with a composition of 1:1. The interface resistance of the LiFePO4 cathode is stabilized when the IL is added to the electrolyte. A reversible capacity of 155 mAh g−1 at C/12 is obtained with cells having at least some organic electrolyte compared to only 124 mAh g−1 with pure IL. With increasing discharge rate, the capacity is maintained close to that in the organic solvent up to 2 C rate. At higher rates, the results with mixture electrolytes start to deviate from the pure organic electrolyte cell. The evaluation of the Li-ion cells; LiFePO4//Li4Ti5O12 with organic and, 40% mixture electrolytes showed good 1st CE at 98.7 and 93.0%, respectively. The power performance of both cell configurations is comparable up to 2 C rate. This study indicates that safety and electrochemical performance of the Li-ion battery can be improved by using mixed IL and organic solvents.

Electrochemical and interfacial characteristics of Li-ion battery system based on LiFePO4 cathode and graphite anode with ionic liquid (IL) electrolytes have been investigated, both with and without addition of a small amount of polymer to the electrolyte. The IL electrolyte consisted of bis(fluorosulfonyl)imide (FSI) as anion and 1-ethyl-3-methyleimidazolium (EMI) or N-methyl-N-propylpyrrolidinium (Py13) as cation, and operated at ambient temperature. We reported previously that the SEI formation with IL was stabilized in the graphite anode at 80% coulombic efficiency (CE) in the first cycle, when FSI anion is used. In this work, we extend the study to the LiFePO4 cathode material. Gel polymer with IL is one part of this study. The stepwise impedance spectroscopy was used to characterize the Li/IL-Gel polymer/LiFePO4 at different states of charge. This technique revealed that the interface resistance was stabilized when the cathode is at 70% DoD (Depth of Discharge). The diffusion resistance is higher at the two extremes of discharge when monophase LiFePO4 state (0%DoD and 100%DoD) obtains. When polymer is added to the IL, interface resistance is improved with 1 wt.% but results with IL alone are not improved for the case of 5 wt.% polymer added. Good cycling life stability was obtained with Li/IL-FSI/LiFePO4 cells, with or without polymer. The first evaluation of the Li-ion cell, LiFePO4/IL-FSI-(5 wt.%) gel polymer/graphite, has shown low first CE at 68.4% but it recovers in the third cycle, to 96.5%. Some capacity fade was noticed after 30 cycles. The rate capability of the Li-ion cell shows a stable capacity until 2 C discharge rate.

Ambient-temperature ionic liquids (IL) based on bis(fluorosulfonyl)imide (FSI) as anion and 1-ethyl-3-methyleimidazolium (EMI) or N-methyl-N-propylpyrrolidinium (Py13) as cations have been investigated with natural graphite anode and LiFePO4 cathode in lithium cells. The electrochemical performance was compared to the conventional solvent EC/DEC with 1 M LiPF6 or 1 M LiFSI. The ionic liquid showed lower first coulombic efficiency (CE) at 80% compared to EC–DEC at 93%. The impedance spectroscopy measurements showed higher resistance of the diffusion part and it increases in the following order: EC–DEC–LiFSI

Iron–carbonized aerogel nanocomposite was prepared from highly porous polyacrylonitrile microcellular foams containing a salt of iron, followed by carbonization. The electrochemical reduction of oxygen at this material was studied by using the rotating disk electrode method. In common with Pt/C, iron–carbonized aerogel nanocomposite presented excellent electrocatalytic activity for the oxygen reduction under experimental conditions close to those of a fuel cell cathode, that is, at the catalyst/Nafion interface in acidic solutions.

Sastry and Parikh [Med. Hypotheses 60(4) (2003) 573] have recently sought an explanation for the fact that the occurrence of a particular cancer in populations in a developing country such as India takes place at a younger age (about one decade) than in populations in Western countries. They have hypothesized that a higher infectious burden in India gives rise to repeated cell divisions leading to early senescence of immune cells, and, thence their reduced ability for immune surveillance against cancer, resulting in earlier onset of cancer. The analysis presented here points out to some difficulties with this interpretation, both on empirical and theoretical grounds. The reduced surveillance ability, caused by higher infectious burden, of the immune cells postulated by Sastry and Parikh [loc. cit.] would also mean that populations in India should suffer higher incidence of cancer, as compared to people in Western countries; the empirical data show that, in fact, quite the opposite is true – Table 1 in the present communication shows that for many common cancers, typical cities in India show the lowest incidence. Theoretically, it is postulated here that repeated heavy infections in India, in fact, challenge the immune system, particularly the adaptive immune system and create an immunological memory : this trains and strengthens the immune system against the future battles. Also it is shown that the shortening of the telomeric cap by repeated cell divisions caused by heavy infectious attacks, as argued by Sastry and Parikh [loc. cit.], is not the cause of earlier onset of cancers among Indians; in fact, when telomeric caps become shortened to a critical point, a danger signal is generated arresting the cell cycle – thus, it provides a fundamental mechanism for ordering the cell to cease proliferation. It is suggested that the root of occurrence of cancers at an earlier age in India perhaps lies in the accumulation of mutations at an earlier age among Indians who do develop cancers; the factors responsible for these accelerated mutations are not clear at the present time and need further investigation.

Non-noble metal-based electrocatalysts have been examined for their electrocatalytic activity toward the reduction of oxygen. These materials were prepared from highly porous polyacrylonitrile microcellular foams containing a salt of iron or cobalt, followed by carbonisation. In common with Pt/C, iron or cobalt-carbonized aerogel nanocomposites show good electrocatalytic activity for the oxygen reduction in acidic solutions. Keywords: Non-noble metal catalyst, Oxygen reduction, Aerogel, Nanocomposite, Iron, Cobalt

Recently some workers in the field of electrostatics have proposed a “new” method of electroosmotic dewatering (EOD) in which a third electrode (called the “gate” electrode) is placed between the anode and the cathode to enhance the EOD. These authors present a conceptual analysis in terms of the notions of a field-effect transistor (FET). We show here that the proposed method is simply a variation of the multistage EOD already practiced by the workers in this field. It is further demonstrated that an analysis based on the FET model is not applicable to the phenomena involved in the proposed EOD method.

Mercury-electroplated iridium microband arrays intended for heavy metal determination purposes were successfully fabricated by means of microelectronic processing techniques. Iridium microbands of 5 μm width each and lengths of 50 μm, 100 μm and 5 mm were investigated and their diffusion behavior and analytical performance compared with those of 5 μm microdisk arrays. The limiting current responses of disk arrays and 5 mm length microband arrays were found to be in good agreement with the radial and hemicylindrical flux expressions, respectively. In contrast, microband arrays having an aspect ratio (length/width) below 50 exhibit diffusion profiles that are characterized by a mixture of both radial and hemicylindrical diffusion components. Such a behavior is thought to be a consequence of edge effects at the extremity of the bands. To perform square-wave anodic stripping voltammetry (SWASV) analysis, the iridium microelectrode arrays were successfully Hg-electroplated and a complete surface coverage was obtained even on microbands having an aspect ratio as high as 1000. The electroanalytical performance of the various Hg-electroplated iridium microelectrode array geometries was evaluated by measuring Cd and Pb ion concentrations in synthetic solutions by means of SWASV over a concentration range as wide as 0.1 to 50 μg L−1. Their detection efficiency (as expressed by the redissolution current normalized to the microelectrodes surface) is shown to be significantly lower than that of microdisk arrays having the same critical dimension (5 μm). Moreover, not only the detection efficiency but also the detection limits were found to decrease as the length of the microbands increases.