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Summary Currently, the lithium-ion battery (LIB) is one of the most viable technologies to enable efficient and clean transportations, which are considered to be crucial for the sustainable development of today's society. However, the energy density of the LIB is approaching its maximum but is still insufficient for meeting the demand of future electric vehicles and other emerging applications. Among all the post LIB chemistries, all solid-state Li metal-intercalation cathode batteries (ASSLICBs) have been capturing attention due to the relatively straightforward cell chemistries compared with Li-S and Li-O2/air batteries, and the intrinsically enhanced safety with the use of solid electrolytes. In this perspective, in-depth analyses of the attainable energy density, overall safety, and cost for ASSLICBs are presented. The existing approaches from literature toward the claimed energy density and safety are intensively discussed. Possible solutions of the remaining challenges and new directions are also given, aiming at designing practical and high-performance ASSLICBs.

With a remarkably higher theoretical energy density compared to lithium-ion batteries (LIBs) and abundance of elemental sulfur, lithium sulfur (Li-S) batteries have emerged as one of the most promising alternatives among all the post LIB technologies. In particular, the coupling of solid polymer electrolytes (SPEs) with the cell chemistry of Li-S batteries enables a safe and high-capacity electrochemical energy storage system, due to the better processability and less flammability of SPEs compared to liquid electrolytes. However, the practical deployment of all solid-state Li-S batteries (ASSLSBs) containing SPEs is largely hindered by the low accessibility of active materials and side reactions of soluble polysulfide species, resulting in a poor specific capacity and cyclability. In the present work, an ultrahigh performance of ASSLSBs is obtained via an anomalous synergistic effect between (fluorosulfonyl)(trifluoromethanesulfonyl)imide anions inherited from the design of lithium salts in SPEs and the polysulfide species formed during the cycling. The corresponding Li-S cells deliver high specific/areal capacity (1394 mAh g

Inverse vulcanization copolymers (p(S-DVB)) from the radical polymerization of elemental sulfur and divinylbenzene (DVB) have been studied as cathode active materials in poly(ethylene oxide) (PEO)-based all-solid-state Li-S cells. The Li-S cell comprising the optimized p(S-DVB) cathode (80:20 w/w S/DVB ratio) and lithium bis(fluorosulfonyl)imide/PEO (LiFSI/PEO) electrolyte shows high specific capacity (ca. 800 mAh g −1 ) and high Coulombic efficiency for 50 cycles. Most importantly, polysulfide (PS) shuttle is highly mitigated due to the strong interactions of PS species with polymer backbone in p(S-DVB). This is demonstrated by the stable cycling of the p(S-DVB)-based cell using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/PEO electrolyte, where successful charging cannot be achieved even at the first cycle with plain elemental S-based cathode material due to the severe PS shuttle phenomenon. These results suggest that inverse vulcanization copolymers are promising alternatives to elemental sulfur for enhancing the electrochemical performance of PEO-based all-solid-state Li-S cells.

Nanocomposite solid polymer electrolytes (NSPEs) comprising lithium salt based on two representative sulfonylimide anions (i.e., bis(fluorosulfonyl)imide ([N(SO2F)2]−, FSI−) and bis(trifluoromethanesulfonyl)imide ([N(SO2CF3)2]−, TFSI−)) have been prepared by simply dissolving the corresponding lithium salt in poly(ethylene oxide) matrix in the presence of inert nano-sized Al2O3 fillers. The physicochemical and electrochemical properties of the FSI- and TFSI-based NSPEs are investigated, in terms of phase transition, ion transport behavior, chemical and electrochemical compatibility with Li metal. With the addition of nano-sized Al2O3 fillers, a significant improvement in chemical and electrochemical compatibility with Li metal has been observed in both the FSI- and TFSI-based NSPEs. Particularly, the symmetric cell using the FSI-based NSPE can be continuously cycled for > 1000 h at 70 °C. The Li | LiFePO4 cell with the FSI-based NSPEs shows good cycling stability and capacity retention. These promising results make them attractive electrolytes for safe and stable rechargeable Li metal batteries.

Novel solid polymer electrolytes (SPEs), comprising of comb polymer matrix grafted with soft and disordered polyether moieties (Jeffamine®) and lithium bis(fluorosulfonyl)imide (LiFSI) are investigated in all-solid-state lithium metal (Li°) polymer cells. The LiFSI/Jeffamine-based SPEs are fully amorphous at room temperature with glass transitions as low as ca. −55 °C. They show higher ionic conductivities than conventional poly(ethylene oxide) (PEO)-based SPEs at ambient temperature region, and good electrochemical compatibility with Li° electrode. These exceptional properties enable the operational temperature of Li° | LiFePO4 cells to be decreased from an elevated temperature (70 °C) to room temperature. Those results suggest that LiFSI/Jeffamine-based SPEs can be promising electrolyte candidates for developing safe and high performance all-solid-state Li° batteries.

New synthesis route of polysalt with single ion conductivity based on functionalization of polyacrylic acid is reported for all solid state lithium metal batteries. Poly[(trifluoromethyl)sulfonyl acrylamide] PA–LiTFSI was synthesized in two steps reaction. The degree of functionalization of the polymer backbone by anion of lithium salt bis(trifluoromethane)sulfonimide (LiTFSI) was confirmed by ICP analysis. An ionic conductivity equal 1,77 10 −5 S cm −1 at 80 °C of polysalt blended with PEO is reported. Easy process-able polysalt blended with PEO exhibits good mechanical properties and high transference number.

Of the various beyond-lithium-ion battery technologies, lithium-sulfur (Li-S) batteries have an appealing theoretical energy density and are being intensely investigated as next-generation rechargeable lithium-metal batteries. However, the stability of the lithium-metal (Li°) anode is among the most urgent challenges that need to be addressed to ensure the long-term stability of Li-S batteries. Herein, we report lithium azide (LiN3 ) as a novel electrolyte additive for all-solid-state Li-S batteries (ASSLSBs). It results in the formation of a thin, compact and highly conductive passivation layer on the Li° anode, thereby avoiding dendrite formation, and polysulfide shuttling. It greatly enhances the cycling performance, Coulombic and energy efficiencies of ASSLSBs, outperforming the state-of-the-art additive lithium nitrate (LiNO3 ).

Solid polymer electrolytes (SPEs) comprising lithium bis(fluorosulfonyl)imide (Li[N(SO2F)2], LiFSI) and poly(ethylene oxide) (PEO) have been studied as electrolyte material and binder for the Li–S polymer cell. The LiFSI-based Li–S all solid polymer cell can deliver high specific discharge capacity of 800 mAh gsulfur–1 (i.e., 320 mAh gcathode–1), high areal capacity of 0.5 mAh cm–2, and relatively good rate capability. The cycling performances of Li–S polymer cell with LiFSI are significantly improved compared with those with conventional LiTFSI (Li[N(SO2CF3)2]) salt in the polymer membrane due to the improved stability of the Li anode/electrolyte interphases formed in the LiFSI-based SPEs. These results suggest that the LiFSI-based SPEs are attractive electrolyte materials for solid-state Li–S batteries.

We report a simple synthesis route towards a new type of comb polymer material based on polyether amines oligomer side chains (i.e., Jeffamine® compounds) and a poly(ethylene-alt-maleic anhydride) backbone. Reaction proceeds by imide ring formation through the NH2 group allowing for attachment of side chains. By taking advantage of the high configurational freedoms and flexibility of propylene oxide/ethylene oxide units (PO/EO) in Jeffamine® compounds, novel polymer matrices were obtained with good elastomeric properties. Fully amorphous solid polymer electrolytes (SPEs) based on lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and Jeffamine®-based polymer matrices show low glass transition temperatures around −40 °C, high ionic conductivities and good electrochemical stabilities. The ionic conductivities of Jeffamine-based SPEs (5.3 × 10−4 S cm−1 at 70 °C and 4.5 × 10−5 S cm−1 at room temperature) are higher than those of the conventional SPEs comprising of LiTFSI and linear poly(ethylene oxide) (PEO), due to the amorphous nature and the high concentration of mobile end-groups of the Jeffamine-based polymer matrices rather than the semi-crystalline PEO The feasibility of Jeffamine-based compounds in lithium metal batteries is further demonstrated by the implementation of Jeffamine®-based polymer as a binder for cathode materials, and the stable cycling of Li|SPE|LiFePO4 and Li|SPE|S cells using Jeffamine-based SPEs.

All solid-state lithium batteries (ASSLBs), with the elimination of flammable liquid solvents and possible safe use of high capacity electrodes, are believed to unlock the bottlenecks in energy density and safety for current Li-ion batteries. Being sandwiched between a highly reductive anode and an oxidative cathode, the nature of solid electrolytes (SEs) plays a pivotal role in dictating the electrochemical performance of ASSLBs. In this chapter, a brief introduction to the transport properties of SEs and a detailed survey of the status of research on SEs are presented. In particular, attention is paid to the very recent interesting findings and breakthroughs in the field of SEs, instead of screening/analyzing the physicochemical and electrochemical properties of reported electrolytes, which have been scrutinized in recently published reviews. Furthermore, remarks and thoughts on the existing challenges and future outlook are depicted.

Electrochemical energy storage is one of the main societal challenges to humankind in this century. The performances of classical Li-ion batteries (LIBs) with non-aqueous liquid electrolytes have made great advances in the past two decades, but the intrinsic instability of liquid electrolytes results in safety issues, and the energy density of the state-of-the-art LIBs cannot satisfy the practical requirement. Therefore, rechargeable lithium metal batteries (LMBs) have been intensively investigated considering the high theoretical capacity of lithium metal and its low negative potential. However, the progress in the field of non-aqueous liquid electrolytes for LMBs has been sluggish, with several seemingly insurmountable barriers, including dendritic Li growth and rapid capacity fading. Solid polymer electrolytes (SPEs) offer a perfect solution to these safety concerns and to the enhancement of energy density. Traditional SPEs are dual-ion conductors, in which both cations and anions are mobile and will cause a concentration polarization thus leading to poor performances of both LIBs and LMBs. Single lithium-ion (Li-ion) conducting solid polymer electrolytes (SLIC-SPEs), which have anions covalently bonded to the polymer, inorganic backbone, or immobilized by anion acceptors, are generally accepted to have advantages over conventional dual-ion conducting SPEs for application in LMBs. A high Li-ion transference number (LTN), the absence of the detrimental effect of anion polarization, and the low rate of Li dendrite growth are examples of benefits of SLIC-SPEs. To date, many types of SLIC-SPEs have been reported, including those based on organic polymers, organic-inorganic hybrid polymers and anion acceptors. In this review, a brief overview of synthetic strategies on how to realize SLIC-SPEs is given. The fundamental physical and electrochemical properties of SLIC-SPEs prepared by different methods are discussed in detail. In particular, special attention is paid to the SLIC-SPEs with high ionic conductivity and high LTN. Finally, perspectives on the main challenges and focus on the future research are also presented.

A High-Temperature Metal-Air Battery (HTMAB) prototype based on a simple redox reaction between molten Sn and atmospheric oxygen at 800 °C is presented, using yttria doped zirconia as solid electrolyte. Basic reversibility measurements indicate that the electrochemical reactions in the device are reversible with coulombic efficiencies higher than 95%. Significant influence of the cycling rate in the delivered capacity is detected; specifically it is increased from 8 to 90 mAh cm−2 when reducing the discharge current from 12.5 to 0.56 mA cm−2. EIS analysis performed over cycling shows that anode diffusion polarization increase due to sealing deficiencies is the main cause of degradation. Anyway, the electrochemical Sn oxidation/reduction reaction remains reversible for more than 4500 charge-discharge cycles and 6000 hours operating at 800 °C.

Lithium-Sulfur (Li-S) battery technology is one of the promising candidates for next generation energy storage systems. Many studies have focused on the cathode materials to improve the cell performance. In this work we present a series of poly (S-DVB) copolymers synthesised by inverse vulcanization of sulfur with divinylbenzene (DVB). The poly (S-DVB) cathode shows excellent cycling performances at C/2 and C/4 current rates, respectively. It was demonstrated poly (S-DVB) copolymer containing 20% DVB did not influence the electrochemical performance of the sulfur material, compared to elemental sulfur as high specific capacities over ∼700 mAh g −1 at 500 cycles were achieved at C/4 current rate, comparable to conventional carbon-based S cathodes. However, the use of copolymer network is assumed to act firstly as sulfur reservoir and secondly as mechanical stabilizer, enhancing significantly the cycling lifetime. The Li-poly (S-DVB) cell demonstrated an extremely low degradation rate of 0.04% per cycle achieving over 1600 cycles at C/2 current rate.

With the exponential growth of technology in mobile devices and the rapid expansion of electric vehicles into the market, it appears that the energy density of the state-of-the-art Li-ion batteries (LIBs) cannot satisfy the practical requirements. Sulfur has been one of the best cathode material choices due to its high charge storage (1675 mAh g−1), natural abundance and easy accessibility. In this paper, calculations are performed for different cell design parameters such as the active material loading, the amount/thickness of electrolyte, the sulfur utilization, etc. to predict the energy density of Li-S cells based on liquid, polymeric and ceramic electrolytes. It demonstrates that Li-S battery is most likely to be competitive in gravimetric energy density, but not volumetric energy density, with current technology, when comparing with LIBs. Furthermore, the cells with polymer and thin ceramic electrolytes show promising potential in terms of high gravimetric energy density, especially the cells with the polymer electrolyte. This estimation study of Li-S energy density can be used as a good guidance for controlling the key design parameters in order to get desirable energy density at cell-level.

Owing to resource abundance, and hence, a reduction in cost, wider global distribution, environmental benignity, and sustainability, sodium-based, rechargeable batteries are believed to be the most feasible and enthralling energy-storage devices. Accordingly, they have recently attracted attention from both the scientific and industrial communities. However, to compete with and exceed dominating lithium-ion technologies, breakthrough research is urgently needed. Among all non-electrode components of the sodium-based battery system, the electrolyte is considered to be the most critical element, and its tailored design and formulation is of top priority. The incorporation of a small dose of foreign molecules, called additives, brings vast, salient benefits to the electrolytes. Thus, this review presents progress in electrolyte additives for room-temperature, sodium-based, rechargeable batteries, by enlisting sodium-ion, Na-O2 /air, Na-S, and sodium-intercalated cathode type-based batteries.

Journal of the Electrochemical Society 165(1), A6008-A6016 (2018). doi:10.1149/2.0041801jes special issue: "JES Focus Issue on Lithium-Sulfur Batteries : Materials, Mechanisms, Modeling, and Applications", Published by IOP Publishing, Bristol

Lithium-sulfur batteries (Li-S) are identified as one of the most promising rechargeable energy systems due to their high theoretical capacity, high gravimetric energy density, low cost and low environmental impact. However, the insulating nature of sulfur and the migration of soluble polysulfides during discharge limit their practical application. In an attempt to mitigate these drawbacks here we report the preparation of a novel composite formed by hydrothermally reduced graphene oxide (HrGO) and submicrometer-sized sulfur particles. The role of HrGO is not restricted to enhance the electronic conductivity of the composite, but also sulfur wrapping in order to prevent polysulfides migration. Besides, the addition of polyvinylpyrrolidone (PVP) during the synthesis of the sulfur particles allows a greater control of their size and improves its homogeneous distribution within the composite. The material is tested as cathode for Li-S batteries showing reversible capacities over 900 mAh g−1 at a rate of 0.2 C and more than 650 mAh g−1 after 100 charge-discharge cycles. Moreover, this simplistic and environmentally friendly approach allow obtaining composites with sulfur loadings as high as 92 wt%, and large areal capacities up to 1.5 mAh cm−2.

Lithium metal (Li0 ) rechargeable batteries (LMBs), such as systems with a Li0 anode and intercalation and/or conversion type cathode, lithium-sulfur (Li-S), and lithium-oxygen (O2 )/air (Li-O2 /air) batteries, are becoming increasingly important for electrifying the modern transportation system, with the aim of sustainable mobility. Although some rechargeable LMBs (e.g. Li0 /LiFePO4 batteries from Bollore Bluecar, Li-S batteries from OXIS Energy and Sion Power) are already commercially viable in niche applications, their large-scale deployment is hampered by a number of formidable challenges, including growth of lithium dendrites, electrolyte instability towards high voltage intercalation-type cathodes, the poor electronic and ionic conductivities of sulfur (S8 ) and O2 , as well as their corresponding reduction products (e.g. Li2 S and Li2 O), dissolution, and shuttling of polysulfide (PS) intermediates. This leads to a short lifecycle, low coulombic/energy efficiency, poor safety, and a high self-discharge rate. The use of electrolyte additives is considered one of the most economical and effective approaches for circumventing these problems. This Review gives an overview of the various functional additives that are being applied and aims to stimulate new avenues for the practical realization of these appealing devices.

Polymer-rich composite electrolytes with lithium bis(fluorosulfonyl)imide/poly(ethylene oxide) (LiFSI/PEO) containing either Li-ion conducting glass ceramic (LICGC) or inorganic Al2O3 fillers are investigated in all-solid-state Li–S cells. In the presence of the fillers, the ionic conductivity of the composite polymer electrolytes (CPEs) does not increase compared to the plain LiFSI/PEO electrolyte at various tested temperatures. The CPE with Al2O3 fillers improves the stability of the Li/electrolyte interface, while the Li–S cell with a LICGC-based CPE delivers high sulfur utilization of 1111 mAh g–1 and areal capacity of 1.14 mAh cm–2. In particular, the cell performance gets further enhanced when combining these two CPEs (Li | Al2O3–CPE/LICGC–CPE | S), reaching a capacity of 518 mAh g–1 and 0.53 mAh cm–2 with Coulombic efficiency higher than 99% at the end of 50 cycles at 70 °C. This study shows that the CPEs can be promising electrolyte candidates to develop safe and high-performance all-solid-state L...

The cycling performance fade of LFP-based Li-ion cylindrical batteries is evaluated under maximum cycling voltage amplitude. Diagnostic evaluation of the aging mechanisms included in situ electroch...

The present study aims at establishing a methodology for a comprehensive calendar ageing predictive model development, focusing specially on validation procedures. A LFP-based Li-ion cell performance degradation was analysed under different temperature and SOC storage conditions. Five static calendar ageing conditions were used for understanding the ageing trends and modelling the dominant ageing phenomena (SEI growth and the resulting loss of active lithium). The validation process included an additional test under other constant operating conditions (static validation) and other four tests under non–constant impact factors operating schemes within the same experiment (dynamic validation), in response to battery stress conditions in real applications. Model predictions are in good agreement with experimental results as the residuals are always below 1% for experiments run for 300–650 days. The model is able to predict dynamic behaviour close to real operating conditions and the level of accuracy corresponds to a root-mean-square error of 0.93%.

A High-Temperature Metal–Air Battery (HTMAB) that operates based on a simple redox reaction between molten metal and atmospheric oxygen at 600–1000 °C is presented. This innovative HTMAB concept combines the technology of conventional metal–air batteries with that of solid oxide fuel cells to provide a high energy density system for many applications. Electrochemical reversibility is demonstrated with 95% coulomb efficiency. Cell sealing has been identified as a key issue in order to determine the end-of-charge voltage, enhance coulomb efficiency and ensure long term stability. In this work, molten Sn is selected as anode material. Low utilization of the stored material due to precipitation of the SnO2 on the electrochemically active area limits the expected capacity, which should theoretically approach 903 mAh g−1. Nevertheless, more than 1000 charge/discharge cycles are performed during more than 1000 h at 800 °C, showing highly promising results of stability, reversibility and cyclability.

Metal supported cells (MSC) are considered as the next generation of Solid Oxide Fuel Cells due to their robustness and cost-efficiency. However, improvement of their performances for operation below 700°C is a key point, as well as their durability and their manufacturing route. Within the RAMSES EU project, materials, components and processes have been tailored for MSCs. Thus, a metal substrate, with coating, has been optimized, fulfilling the targets of low-cost, sinterability in low-oxidizing atmosphere and oxidation resistance. A customized electrolyte powder allowed decreasing the sintering temperature of 100°C compared to a reference 8YSZ powder. A modified Ni-8YSZ anode as well as a nickelate cathode were found to reach low polarization resistances of respectively 0.37 and less than 0.20 Ohm.cm² at 600°C. The progressive implementation of these materials in MSC has led to improved performances in tubular MSC, with an ASR of 1.56 Ohm.cm² at 600°C. Durability over 500h and 500 thermal cycles have been successfully achieved.

Porous Crofer Fe22Cr stainless steel supports for tubular Solid Oxide Fuel Cells (SOFC) were developed and tested successfully under hydrogen fuel with 50% humidification at 800 °C. Corrosion resistance and stability as a function of operation lifetime, porosity and thermal cycling were studied through the investigation of oxide growth and microstructure. Oxidation reactions followed subparabolic kinetics and substrates with porosities between 25 and 40% showed long-term stability over 4500 h and suitable properties for metal‐supported SOFC technology application.

(La0.6Sr0.4)(0.95)FeO3-delta/Sm0.2Ce0.8O2 (70:30, w/w) and (La0.6Sr0.4)(0.995)Co0.2Fe0.8O3-delta/Gd0.1Ce0.9O2 (50:50, w/w) cathodes screen printed on anode-supported cells were tested for 500h under different conditions by using a Taguchi matrix that combines cathode processing parameters (material composition, thickness, and sintering temperature) and operation conditions (temperature, current density, air flux, air humidification and chromium presence). Activation time increases with current density and varies with sintering temperature. Individual effect of each control factor on cell performance degradation was evaluated: chromium poisoning, air humidity and temperature were classified, in such order, as the most influencing parameters for cathode and cell degradation. Unexpected high degradation rates are reported at 750 degrees C. Limited influence of the type of cathode on long-term cells behavior is observed: LSF/SDC cathodes exhibits, however, higher long-term stability. (C) 2011 Elsevier Ltd. All rights reserved.

Tubular metal supported SOFC technology has successfully been developed over the past years with the aim at domestic CHP systems below 3 kWe. The basic cell structure consists of a metal porous support, a protective barrier layer, an anode and an electrolyte cofired at 1350ºC. Cathode and contacting layers are subsequently sintered at lower temperatures. The most significant results to date include successful thermal cycling of the cell and anodic connection during 450 cycles and 2000 hours, oxidation testing of the metal support for more than 2500 hours and a comparison of influence of porosity during 100 hours oxidation of metal porous substrates under high water vapour atmospheres.

The stability of tubular metal supported SOFC has been studied as a function of current load, thermal cycles and interconnect-sealing concepts. Long term testing under applied current at 800ºC have been performed over 1000 hours on standard cells. Thermal cycles have been proven intensely (250 cycles) during over 700 hours. Major cause for degradation has been identified in terms of the anode interconnect-sealing design, which involves specific handling and machining of tubes and generation of initial submicron cracks. Cell microstructure seems stable after 1000 hours testing at 300 mA/cm2 and 800ºC.

A family of iron perovskites with the general formula AFeO 3− δ (A = Ln 1− x M x ; Ln = La, Nd and/or Pr; M = Sr or/and Ca) has been prepared keeping fixed the A cation radius 〈 r A 〉 and cation size mismatch to isolate the effect of divalent dopant concentration from the A-cation steric effects. The electrochemical behaviour of these compounds for their application as SOFC cathodes was evaluated by using I – V curve measurements and ac impedance spectroscopy over three electrodes electrolyte supported cells processed under identical conditions. In contrast with the bulk behaviour, trends are more difficult to observe due to microstructural effects, but results seem to indicate that the doping level, x , does not influence in a significant way the electrochemical performance of iron perovskites with identical 〈 r A 〉 and σ 2 ( r A ).

Doped ceria barrier layers have extensively been used between Fe and/or Co containing cathode materials and conventional yttria-stabilized zirconia (YSZ) electrolytes in Solid Oxide Fuel Cells (SOFCs) to improve performance and prevent unwanted chemical reactions between them. However, the chemical compatibility between the YSZ and doped ceria depends strongly on the sintering temperature and atmosphere. This study focuses on the influence of temperature and sintering atmosphere in the crystal structure, microstructure and conductivity of bulk mixtures of YSZ and Sm 0.2 Ce 0.8 O 1.9 (SDC). Polycrystalline mixtures of YSZ–SDC (50% weight) were sintered between 950 and 1350 °C in air, Ar and hydrogen containing reducing atmospheres. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and electrochemical impedance spectroscopy (EIS) were used to analyse the chemical interactions between SDC and YSZ under different processing conditions. Overall, diffusion between SDC and YSZ is observed for all cases but the solid solution formed depends upon the temperature and the sintering atmosphere. The additional formation of (Ce,Sm) 2 Zr 2 O 7 pyrochlore is observed when sintering under reducing atmosphere. SEM and EDX analysis reveal microstructure variations with higher homogeneity for the samples sintered in argon or hydrogen. The sintering behaviour and the total conductivity properties are also dependent on sintering atmospheres, showing that inert conditions may yield the best performing YSZ–SDC system for SOFC applications.

Detailed X-ray diffraction (XRD) analysis of two different Sr-doped LaFeO3 cathodes, YSZ electrolyte and two Sm/Gd-doped CeO2 interlayer and their mixtures were used to evaluate the formation of undesired secondary reaction compounds. The analysis of room temperature X-ray diffraction data of the mixtures indicates the crystallization of strontium and/or lanthanum zirconates between the cathode and the electrolyte materials and no detected reaction between the cathode and the interlayer materials. For all the ferrite mixtures a significant shift in the diffraction peaks is observed, which is the result of the unit cell volume expansion and contraction of the cathode (LSF) structures mixed with electrolyte (YSZ), and with interlayers (SDC, GDC), respectively. On the other hand, a complete solid solution was observed between the crystal structures of YSZ electrolyte and SDC or GDC interlayers. The observed cell modifications for the ferrite mixtures were the result of the incorporation of Zr and Ce, in the B and A type positions of the perovskite structure, respectively. The electrolyte/interlayer interface shows the presence of intermediate compositions at high temperature. The electrochemical studies show better results when a Sm-doped CeO2 is inserted between the cathode and electrolyte material. The best result obtained is for the half-cell prepared with LSF-40 and SDC interlayer on YSZ electrolyte.

A novel methodology for lifetime prognosis of Li-ion cells is presented, covering the validity and accuracy assessment of the predictions. It is especially focused on the procedures for the evaluation of semi-empirical ageing model development process. Combined calendar and cycle ageing is investigated with dynamic and realistic complex operation profiles, as part of the stepwise validation methodology that is proposed. The dynamic validation approach allows identifying the sources of model errors by analysing how the individual stress factors are adjusted under non-constant profiles. The results correspond to a LFP-based 26650-size cell. The presented model is suitable for different applications, such as elevator or vehicle combined with vehicle-to-grid (V2G) use, with 1.4% root-mean-square error accuracy.

A series of iron perovskites with the general formula AFeO 3− δ (A = Ln 1− x M x ; Ln = La, Nd and/or Pr; M = Sr and/or Ca) has been prepared by conventional solid state reaction. In order to isolate the effect of divalent dopant concentration from the A cation steric effects, the whole group has a fixed mean A cation radius r A > ≈ 1.22 A and cation size disorder σ 2 ( r A ) ≈ 0.003 A 2 but variable doping x . The structure changes with x from orthorhombic (0.2 ≤ x ≤ 0.4) through rhombohedral (0.5 ≤ x ≤ 0.7) to a mixture of rhombohedral and cubic for x = 0.8. SEM images show that the average grain size increases with alkaline–earth content. All samples show a systematic dependence of conductivity upon doping, which can be directly related to the concentration of charge carriers. Conductivity fits indicate a p -type semiconducting, small-polaron hopping mechanism, in which the activation energies remain similar for all doping levels, x , throughout the series.

As a way of reducing the production costs of stacks by replacing ceramic components with metal components with a similar thermal expansion coefficient (TEC), today, much of the research work has focused on SOFCs operating at temperatures of under 800 °C. Some semi-commercial ferritic stainless steels (FSS) satisfy this TEC. Ikerlan has evaluated samples of two of these. Also, AMETEK stainless steel powders were tested in sintered disks until they were completely densified in order to compare results from dense and porous materials. The first tests performed by Ikerlan were conducted with dense samples and included the oxidation test in air at 800 °C and measurements of contact surface electrical resistance (area specific resistance, ASR), to compare electrochemical techniques (electrochemical impedance spectroscopy, EIS) with the traditional four-wire method and indirect measuring of the resistance through current and voltage measurements. An alloy from the last melt manufactured by the company ThyssenKrupp VDM GmbH performed best. These results did not differ greatly from the previous laboratory results attained during alloy development. Only AMETEK powder metallurgy materials were tested as porous bodies, to compare these with these dense materials, and were found to provide much higher oxidation levels, as might be expected. While dense materials can operate under the working conditions of the SOFC, porous materials still need new alloys.

A series of Ln0.7M0.3MnO3 perovskites (Ln=La, Pr, Nd and M=Ca, Sr, Ba) with fixed mean A-cation radius, =1.26 A and variable A cation size disorder, quantified by the variance σ3 is studied. The results on seven samples show that the electronic, magnetic and structural transitions are affected by changes in σ2. Furthermore, the Curie and metal-insulator transition temperatures are sensitive to the perovskite superstructure which changes from rhombohedral R 3 c to orthorhombic Imma as σ2 increases.

A series of five Ln0.7M0.3MnO3 perovskites (Ln=trivalent lanthanide; M=divalent alkaline earth) has been prepared. These have the same mean A-cation site radius of 1.26 A (equivalent to a perovskite tolerance factor of 0.98) but varying amounts of A-cation size disparity quantified by the size variance σ2. As this increases, the temperatures of the metal–insulator and Curie transitions show a strong linear decrease but that of the structural transition between rhombohedral R 3 c and orthorhombic Imma phases increases. Extrapolation from these and previous data indicates that the maximum metal–insulator temperature for an Ln0.7M0.3MnO3 perovskite is ∼550 K. Different methods for estimating the Curie temperature are compared.

Reaction of 4-chloropyridine hydrochloride with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinoxyl in the presence of five equivalents of powdered KOH in DMSO at 30°C affords L1 in 10-50 yield after an aqueous quench. The complexes M(L1)4(BF4)2 (M=Ni, 1; M=Cu, 2; M=Pd, 3) have been prepared by complexation of hydrated M(BF4)2 (M=Ni, Cu), or PdCl2(NCPh)2+2AgBF4, by four equivalents of L1 in MeCN. Diffusion of Et2O into MeCN solutions of 2 affords two crystalline polymorphs of this complex, both containing square planar Cu(L1)42+dications Cu-N=2.005(7)-2.042(6) A . The major, monoclinic form contains axial Cu...NCMe contacts of 2.394(7) and 2.859(8) A , while the minor, triclinic form exhibits long axial Cu...FBF3 bonds (Cu...F=2.478(5), 2.551(5) A ). In both structures, the Cu...N(nitroxyl) distances are 9.5-9.7 A . The Q-band EPR spectrum of 2 in 10:1 MeCN:toluene solution at 293 K is a broad featureless line, suggesting JCu-L1�0.07 cm-1. Variable temperature susceptibility measurements on powdered 2 and 3 show weakly antiferromagnetic behaviour. For 2 these data are well reproduced both by the Curie-Weiss law and by a model describing intramolecular superexchange; for 3, the data could not be fit satisfactorily, suggesting the presence of a significant intermolecular superexchange pathway.

Structural changes in a series of 30% hole-doped $A{\mathrm{MnO}}_{3}$ perovskites have been studied by powder neutron diffraction. Large local changes, consistent with the freezing of Jahn-Teller distortions of the ${\mathrm{MnO}}_{6}$ octahedra, occur at the metal-insulator transition at ${T}_{m}=363$ K in ${(\mathrm{L}\mathrm{a}}_{0.70}{\mathrm{Ca}}_{0.11}{\mathrm{Sr}}_{0.19}){\mathrm{MnO}}_{3}.$ The 4 K structures of four compositions with the same A-cation radius but increasing amounts of A-site disorder, show an increasing radial distortion of the ${\mathrm{MnO}}_{6}$ octahedra. The decrease in ${T}_{m}$ across this series may reflect these increasing distortions which lower the local strain contribution to the transition enthalpy.

Degradation mechanisms inherent to ferritic LSF-SDC and LSCF-GDC cathodes are studied by post-mortem analysis of cells which suffered the most significant performance deterioration in a set of 18 500 h tests carried out under a specific experimental design. Three cathode processing parameters (composition, thickness, and sintering temperature) were combined with five operation conditions (chromium presence, current density, operating temperature, air flow, and humidification) through this design of experiments based in a L18 Taguchi matrix. In the case of cells exposed to chromium vapors from Crofer 22 APU pieces, those cells which exhibited K2Cr2O7 deposition in the cathode/GDC barrier interface underwent the most aggressive ASR degradation. Similar deposits were also observed on the surface of LSC current collectors. Two cells exposed to highly humidified air (20%) exhibited cathode delamination and GDC barrier deterioration by crack propagation though no foreign elements diffusion to the interface could be detected.

Large disorder effects due to size differences between $A$-site ${R}^{3+}$ ($R=\mathrm{L}\mathrm{a},\phantom{\rule{0ex}{0ex}}\mathrm{P}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{N}\mathrm{d},\phantom{\rule{0ex}{0ex}}\mathrm{S}\mathrm{m}$) and ${M}^{2+} (M=\mathrm{C}\mathrm{a},\phantom{\rule{0ex}{0ex}}\mathrm{S}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{B}\mathrm{a})$ cations have been found in magnetoresistive $({R}_{0.7}{M}_{0.3})\mathrm{Mn}{\mathrm{O}}_{3}$ perovskites. The ferromagnetic-metal-paramagnetic-insulator transition temperature ${T}_{m}$ varies as ${T}_{m}={T}_{m}(0)\ensuremath{-}p{Q}^{2}$ due to strain fields resulting from ordered or disordered oxygen displacements $Q$ that are parametrized by the statistical mean and variance of the $A$ cation radius, respectively. The value of $p$ is related to the Mn-O force constant showing that ${\mathrm{Mn}}^{3+}$ Jahn-Teller distortions assist electron localization at ${T}_{m}$. The maximum possible ${T}_{m}$ is estimated to be \ensuremath{\sim}530 K although experimentally observable values are \ensuremath{\le}360 K. A large suppression of magnetoresistance due to cation disorder is also evidenced.

Li-ion batteries are good candidates for electric vehicles and stationary applications due to their high power and energy density. Despite significant improvement over the last decade, lifetime and safety remain major issues for large-scale applications. Thus, a better understanding of factors governing battery lifetime and performance loss is crucial. Various types of Li-ion batteries are commercially available and their characteristics and performance depend strongly on the combination of active materials, cell design and manufacturing process. Therefore, the determination of specific degradation mechanisms and their correlation with cell performances is crucial for working on cell concepts that can meet target lifetimes [1-3]. In this work, cycling performance fade of LiFePO4-based cylindrical batteries is evaluated under deep charge/discharge steps (100% DOD). The cycling conditions were chosen to represent highly demanding condition of operation, which covers the analysis of ageing phenomena under the largest possible operating DOD. Diagnostic evaluation of the ageing mechanisms included in-situ electrochemical measurements, and ex-situ destructive physico-chemical and electrochemical analyses of cell components. A thorough study on the degradation mechanisms in different areas of the battery is realised in order to establish a geometrical mapping of the cell degradation. This allows identifying areas of inhomogeneous degradation along the jelly-roll of the battery. Degradation mechanisms were evaluated by microstructural (SEM) and crystallographic (XRD) analyses. Elemental analysis of the electrode composition was determined by EDS and ICP techniques. The electrochemical performances of selected areas of the harvested electrodes were determined by galvanostatic testing in half-cell configuration. These results were combined with non-destructive cell electrochemical measurements to provide a global view of the main degradation processes. [1] M. Safari and C. Delacourt, Journal of the Electrochemical Society, 2011. 158(12): p. A1436-A1447. [2] M. Dubarry and B.Y. Liaw, Journal of Power Sources, 2009. 194(1): p. 541-549. [3] D.P. Abraham, J. Liu, C.H. Chen, Y.E. Hyung, M. Stoll, N. Elsen, S. MacLaren, R. Twesten, R. Haasch, E. Sammann, I. Petrov, K. Amine, and G. Henriksen, Journal of Power Sources, 2003. 119-121: p. 511-516.

Doped manganite perovskites AMnO(3) exhibit a rich variety of electronic properties, resulting from the interplay of charge (Mn(3+)/Mn(4+)), spin (Mn magnetic moment) and orbital (Mn(3+) Jahn-Teller distortion) degrees of freedom. Magnetisation measurements and ESR spectra have been used to study a series of eight AMnO(3) perovskites, in which the A cation sites are occupied by a distribution of 70% trivalent lanthanide and 30% divalent Ca, Sr or Ba ions. These all have a mean A cation radius of 1.20 Angstrom but different values of the cation size variance sigma(2). A change from orbital disorder to order (cooperative Jahn-Teller distortions) was previously found in the insulating regime at sigma(2) = approximately 0.005 Angstrom(2). This work has shown that co-existence of the orbitally ordered and disordered phases is found in sigma(2)= 0.0016-0.0040 Angstrom(2) samples, with a difference of 40 K between their Curie temperatures. This is ascribed to competition between orbital ordering and microstructural lattice strains. At larger sigma(2)0.005 Angstrom(2), the orbital ordering strains are dominant and only this phase is observed. This intermediate temperature phase segregation is one of many strain-driven separation phenomena in manganites.

A series of eight ${\mathrm{AMnO}}_{3}$ perovskites in which the A-cation sites are occupied by a distribution of 70% trivalent lanthanide and 30% divalent Ca, Sr, or Ba ions has been prepared. These all have a mean A-cation radius of 1.20 \AA{}, but different values of the size variance ${\ensuremath{\sigma}}^{2}.$ All of the samples show resistive and magnetic transitions from a ferromagnetic metallic to a paramagnetic insulating phase. An abrupt change from orbital disorder to order (cooperative Jahn--Teller distortions) in the insulating regime at ${\ensuremath{\sigma}}^{2}\ensuremath{\approx}0.005{\AA{}}^{2}$ is evidenced by anomalies in the unit cell parameters and conductivity and magnetization data. The dependence of the metal-insulator transition temperature upon A-cation distribution in these and other 30% doped compositions are compared against a simple model and displayed in a general phase diagram.

The magnetic structure of the high-field phase HF in MnWO4 was resolved by single-crystal neutron diffraction at 14.5 T and 2.5 K. It is a spin-flop phase with the same magnetic unit cell as the magnetic ground state, but the magnetic moments switched perpendicular to the applied field. The temperature dependence of the propagation vector for the intermediate, incommensurate phase indicates that the coexistence point of HF, the intermediate phase, and the paramagnetic region might be a Lifshitz-point.

Tubular metal supported SOFC technology has successfully been developed over the past years with the aim at domestic CHP systems below 3 kWe. The basic cell structure consists of a metal porous support, a protective barrier layer, an anode and an electrolyte cofired at 1350ºC. Cathode and contacting layers are subsequently sintered at lower temperatures. Latest achievements include average cell performances of 400 mW/cm2 at 0.7 V and 800ºC, over 350 thermal cycles and more than 1500 hours of steady operation. Several stack concepts are currently being tested and BoP components such as fuel processing, power electronics and control system developed in parallel to achieve a successful micro-CHP proof of concept by the end of 2010.

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