Stability Of Cathode Materials Research Articles

Delithiated states of layered cathode materials: doping and dispersion interaction effects on the structure

Here we present results of density functional theory (DFT) study of delithiated structures of layered LiNiO2 (LNO, Li12Ni12O24 model) cathode material and its doped analogue LiNi0.833Co0.083Al0.083O2 (N10C1A1, Li12Ni10CoAlO24 model). The paper is aimed at independent elucidation of doping and dispersion interaction effects on the structural stability of cathode materials studied. For this purpose, the LNO and N10C1A1 configurational spaces consisting of 87 and 4512 crystallographically independent configurations (obtained starting from 2×2×1 supercell of R-3m structure of LNO) are optimized within a number of DFT models. Based on a comparison of the calculated dependencies for the lattice parameters with the results of in situ neutron diffraction experiments, the most pronounced effect of cathode material stabilization is due to the dispersion interaction. In turn, the doping effect is found to affect cathode structure behavior at the latest stages of delithiation only.

Electrochemical properties and first-principle analysisof Na x [M y Mn1−y ]O2 (M = Fe, Ni) cathode

Sodium-ion batteries are the commercially and environmentally viable next-generation candidates for automobiles. Structural and electrochemical aspects are greater concerns towards the development of a stable cathode material. Selecting transition metals and their composition greatly influences charge order, superstructures, and different voltage plateaus. This, in turn, influences transport properties and cyclic performance. This article aims to study the electrochemical performance, diffusivity, and structural stability of Na x [M y Mn1−y ]O2 (M = Fe, Ni) as cathode. Both experimental and DFT-based calculations apprehend the voltage plateaus due to redox reactions. The rate of cycling and the initial structure also influence the cycle life. The diffusion coefficient of P2-type Na0.67Fe0.5Mn0.5O2 for Mn3+/4+ redox reactions is more than that of the O3-type NaFe0.5Mn0.5O2 while it is less for Fe3+/4+ redox reactions, because of structural transition. The diffusion coefficient of NaNi0.5Mn0.5O2 is less for Ni2+/4+ redox reaction and is up to the order of 10−11 cm2 s−1.

Facile synthesis of hierarchical porous Li2FeSiO4/C as highly stable cathode materials for lithium-ion batteries

Lithium iron silicate has caught tremendous attentions as an appealing cathode for future lithium-ion batteries due to high capacity, low cost, and environmental friendliness, and its drawback of extremely low conductivity can be overcome efficiently through nanoarchitecture building. However, the construction of nanostructures always involves with expensive surfactants and complicated synthetic processes, which restrict these methods from large-scale production. In this paper, we develop a simple synthetic route to prepare hierarchical porous Li2FeSiO4/C. XRD, SEM, TEM, Raman, and N2 adsorption-desorption are employed to investigate its physical properties. Electrochemical tests reveal that the composite delivers a high specific capacity of 243.5 mAh g−1, superior rate capability, and excellent cycling performance with capacity retention of 95.2% after 200 cycles. The excellent electrochemical performance should be attributed to the unique structure in which hierarchical pores provides fast transport channels for lithium ions and interconnected carbon coating builds up conductive networks to enhance the conductivity of Li2FeSiO4. In addition, electrochemical impedance spectroscopy, ex situ SEM, and TEM are conducted to demonstrate its structural stability upon long-term cycling. In addition, the route described in this work is facile, cheap, and easily scaled-up, which allows for extension to the fabrication of other energy storage materials.

Efficient Method of Designing Stable Layered Cathode Material for Sodium Ion Batteries Using Aluminum Doping.

Despite their high specific capacity, sodium layered oxides suffer from severe capacity fading when cycled at higher voltages. This key issue must be addressed in order to develop high-performance cathodes for sodium ion batteries (SIBs). Herein, we present a comprehensive study on the influence of Al doping of Mn sites on the structural and electrochemical properties of a P2-Na0.5Mn0.5-xAlxCo0.5O2 (x = 0, 0.02, or 0.05) cathode for SIBs. Detailed structural, morphological, and electrochemical investigations were carried out using X-ray diffraction, cyclic voltammetry, and galvanostatic charge-discharge measurements, and some new insights are proposed. Rietveld refinement confirmed that Al doping caused TMO6 octahedra (TM = transition metal) shrinkage, resulting in wider interlayer spacing. After optimizing the aluminum concentration, the cathode exhibited remarkable electrochemical performance, with better stability and improved rate performance. Electrochemical impedance spectroscopy (EIS) measurements were performed at various states of charge to probe the surface and bulk effects of Al doping. The material presented here exhibits exceptional stability over 100 cycles within a 1.5-4.3 V window and outperforms several other Mn-Co-based cathodes for SIBs. This study presents a facile method for designing structurally stable cathodes for SIBs.

Morphological and Electrical Stability Studies of Pt/Yttria-Stabilized Zirconia Nanocomposite Thin Film Cathodes for Microfabricated Solid Oxide Fuel Cells

Abstract Microfabricated solid oxide fuel cells (mSOFCs) have recently gained attention as a promising technology for portable power applications. At present, porous Pt is the most common cathode being investigated for mSOFCs, which has poor bulk ionic conductivity and suffers from instability due to Ostwald ripening. Nanocomposite materials based on Pt/Yttria-Stabilized Zirconia (YSZ) are a promising alternative approach for high performance mSOFCs because of their potential for providing mixed ionic-electronic conduction, improving adhesion to the YSZ electrolyte, and improving oxygen diffusion characteristics over a pure Pt material. The objective of this research was to systematically explore the processing of the nanocomposite thin films to achieve stable morphological and electrical properties for use as a mSOFC cathode. A percolation theory model was utilized to guide the processing of the Pt/YSZ composition, ensuring a networked connection of ionic- and electronic-conduction through the electrode. The Pt/YSZ nanocomposite cathodes were deposited by co-sputtering. It was observed that the Ar deposition pressure played a key role in stabilizing the morphology of the film to higher temperatures, up of 600°C. Analyses of the Pt/YSZ composite microstructure and composition by TEM confirmed an interconnected network of Pt and YSZ thereby suggesting that it is a viable candidate as a high performance and stable cathode material for mSOFCs.

Progress in High‐Voltage Cathode Materials for Rechargeable Sodium‐Ion Batteries

AbstractRoom‐temperature rechargeable sodium‐ion batteries are considered as a promising alternative technology for grid and other storage applications due to their competitive cost benefit and sustainable resource supply, triumphing other battery systems on the market. To facilitate the practical realization of the sodium‐ion technology, the energy density of sodium‐ion batteries needs to be boosted to the level of current commercial Li‐ion batteries. An effective approach would be to elevate the operating voltage of the battery, which requires the use of electrochemically stable cathode materials with high voltage versus Na+/Na. This review summarizes the recent progress with the emerging high‐voltage cathode materials for room‐temperature sodium‐ion batteries, which include layered transitional‐metal oxides, Na‐rich materials, and polyanion compounds. The key challenges and corresponding strategies for these materials are also discussed, with an emphasis placed on the intrinsic structural properties, Na storage electrochemistry, and the voltage variation tendency with respect to the redox reactions. The insights presented in this article can serve as a guide for improving the energy densities of room‐temperature Na‐ion batteries.

Dependence of Syngas Composition on Microstructure of La0.8Sr0.2Cr0.5Mn0.5O3–δ Based Cathode for CO2 and H2O Co-Electrolysis

Ceramic materials with perovskite structure have attracted attention as possible redox stable, sulfur- and carbon tolerant cathode materials for solid oxide electrolysis cells 1,2. For example, composite cathode based on La0.8Sr0.2Cr0.5Mn0.5O3-δ (LSCM) are used for high temperature electrolysis of steam and co-electrolysis of steam and carbon dioxide 3,4. However, the limitation of electrochemical performance of electrolysis cell due to insufficient electrocatalytic activity can be a serious challenge 5. In this study, catalytically active nickel and copper nanoparticles were grown on the surface of A-site deficient LSCM via redox exsolution. Influence of water-gas shift reaction activity conditions of electrolysis and nanocatalyst properties on the outlet gas composition were evaluated. Electrolysis cells were prepared by sandwiching dense Zr0.89Sc0.10Ce0.01O2-δ (ScCeSZ) electrolyte layer between porous ScCeSZ layers and followed by wet impregnating of electrocatalytically active electrodes into the porous matrix. Impregnated salt mixture is decomposed at 400 °C, calcined and then sintered at 1400°C for 5 h. The thicknesses of the dense electrolyte and the porous scaffold were approximately 100 μm and 40 μm, respectively. Scanning electron microscopy, X-ray diffraction, FIB-TOF-SIMS and ICP-MS methods were used to characterize materials. Electrochemical characterization and analysis of outlet gas composition using gas chromatography was carried out at temperature range from 650 to 850 °C in various H2O, CO2, H2 and Ar inlet concentrations. As expected, the activity of composite cathode was greatly enhanced by the exsolved nickel and copper nanoparticles. For gas compositions the influence of water-gas shift (WGS) for nickel was greater than for copper. Thus, it has been demonstrated that both nickel and copper nanoparticles can enhance the electrolytic activity of the cathode for steam electrolysis and co-electrolysis of steam and carbon dioxide. Influence of water-gas shift reaction at co-electrolysis conditions and properties of nanocatalysts on the outlet gas composition were evaluated.

Thermally Resistant Film Formation on Carbonaceous Anode Materials Using Vinylene Carbonate Additive for Lithium-Ion Battery

Introduction Currently, the development of lithium ion batteries (LIBs) is toward large-scale ones because electric vehicles (EVs), hybrid electric vehicles (HEVs) and stationary energy storage systems for smart grid community are considered necessary from the viewpoint of clean energy and sustainability. However, the large-scale electronic applications are more likely used in high-temperature environment, thus increasing the risk of battery failure. To overcome this issue, much efforts are put on the development of electrolyte additives, among which vinylene carbonate (VC) is known as an effective one in enhancing the thermal stability of carbonaceous anode material. [1] Nevertheless, the film-forming mechanism induced by VC on the carbonaceous anode surface, particularly at elevated temperature, is not well understood. To clarify the contribution of VC to the formation of thermally resistant film, we use LC-MS together with direct analysis in real time mass spectrometry (DART-MS) to analyze the electrolyte and electrode surface. Experimental The test cell was CR2032 coin cell, in which LiFePO4 and carbonaceous material, namely graphite or hard carbon, are respectively used as cathode and anode materials. For the preparation of cathode, LiFePO4 powders were uniformly mixed with conductive agents and water-based acrylic binder. Similarly, the carbonaceous material was mixed with conductive agents and water-based acrylic binder to make the anode. In addition, the electrolyte was 1 M LiPF6 in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ration of 1:1, and VC was used as an additive. To evaluate the cell’s thermal stability, the charge/discharge cycling tests were performed at 60 °C. For the analysis, the cycled test cells were decomposed, followed by collecting the electrolyte and electrode under an environment with an ultra-low humidity. Next, the collected electrolyte and electrode were respectively moved to the LC-MS and DART-MS apparatuses to analyze the electrolyte and electrode surface. Results and Discussion The test cell with the VC additive shows better cycle performance than that without the additive. Since LiFePO4 is a thermally stable cathode material, the difference in cycle performance can thus be attributed to the interaction between the electrolyte and the carbonaceous anode material. According to the LC-MS analysis, VC is found to suppress the decomposition of lithium salt and solvent, leading to reduced organophosphates as well as carbonate oligomers. It is also found from the DART-MS analysis that VC can assist the formation of thermally resistant organophosphates on the anode surface, preventing further degradation of electrolyte at elevated temperature. This should be the reason for the improved cycle performance for the cell with the VC additive. Reference 1. M. Herstedt, H. Rensmo, H. Siegbahn, and K. Edströma, Electrochim, Acta, 49, 2351–2359 (2004).

Bio-degradable zinc-ion battery based on a prussian blue analogue cathode and a bio-ionic liquid-based electrolyte

Rechargeable zinc-ion batteries are of high interest for electrical energy storage due to their low cost, high safety, and good energy density. The development of stable and high-performance cathode materials and environmentally friendly electrolytes is of interest for practical applications. Despite many efforts in pursuing batteries with high energy density and long cycle life, relatively little attention has been paid on the environmental aspects. Thus, bio-batteries that contain nontoxic materials and which are bio-degradable are an interesting alternative to conventional batteries. In the present paper, we present our first results on a highly reversible zinc/prussian blue analogue (PBA) bio-battery, where nanostructured PBA is used as a cathode material, a bio-degradable ionic liquid-water mixture as electrolyte, and zinc as anode. Both the PBA cathode and the zinc anode exhibit good compatibility with the bio-degradable electrolyte. The Zn/PBA battery shows good electrochemical performance including an open circuit voltage of 1.6 V, a specific capacity of ∼54 mAh g−1 (PBA), and a low self-discharge rate. The zinc anode also shows a good stability since no dendritic growth and shape change are observed after 50 charge-discharge cycles.

Cobalt-doped pyrochlore-structured iron fluoride as a highly stable cathode material for lithium-ion batteries

In the search of high-performance cathodes for next-generation Li-ion batteries (LIBs), iron fluorides are among the most promising materials because of their extremely high theoretical capacity. This study reports on the synthesis, structural and electrochemical characterizations of cobalt doped iron fluoride hydrate as a high-performance cathode material for LIBs. A simple non-aqueous precipitation method is used to synthesize cobalt doped iron fluoride (Fe0.9Co0.1F3·0.5H2O) while its structural and electrochemical properties are also evaluated. The thermogravimetric analysis reveals that the structure of the as-prepared material remains stable up to 243°C. The structure was then found to collapse beyond this temperature due to the removal of water contents from the crystal structure. The material delivers a high discharge capacity of 227mAhg−1 at 0.1C in the potential range of 1.8-4.5V versus Li/Li+. The electrode retains a high reversible capacity of 150mAhg−1 at a rate of 0.1C after 200 cycles, indicating high reversibility and stability of the material. The electrode also shows a superior rate capability of up to 10C, showing its potential use as a cathode material for LIBs.

Lithium intercalation mechanism into FeF3\xb70.5H2O as a highly stable composite cathode material

The growing demand for lithium-ion batteries (LIBs) requires investigation of high-performance electrode materials with the advantages of being environmentally friendly and cost-effective. In this study, a nanocomposite of open-pyrochlore-structured FeF3·0.5H2O and reduced graphene oxide (RGO) is synthesized for use as a high-performance cathode in LIBs, where RGO provides high electrical conductivity to the composite material. The morphology of the composite shows that FeF3·0.5H2O spheres are embedded into RGO layers and high-resolution TEM image shows that those spheres are composed of primary nanoparticles with a size of ~5 nm. The cycling performance indicates that the composite electrode delivers an initial high discharge capacity of 223 mAh g−1 at 0.05 C, a rate capability up to a high C-rate of 10 C (47 mAh g−1) and stable cycle performance at 0.05 C (145 mAh g−1 after 100 cycles) and 0.2 C (93 mAh g−1 after 100 cycles) while maintaining high electrochemical reversibility. Furthermore, the responsible electrochemical reaction is investigated using in-situ XRD and synchrotron-based X-ray absorption spectroscopy (XAS), and the XRD results show that FeF3·0.5H2O transitions to an amorphous-like phase through a lithiation process. However, a reversible oxidation change of Fe3+ ↔ Fe2+ is identified by the XAS results.

Reduced graphene oxide as a stable and high-capacity cathode material for Na-ion batteries

We report the feasibility of using reduced graphene oxide (RGO) as a cost-effective and high performance cathode material for sodium-ion batteries (SIBs). Graphene oxide is synthesized by a modified Hummers’ method and reduced using a solid-state microwave irradiation method. The RGO electrode delivers an exceptionally stable discharge capacity of 240 mAh g−1 with a stable long cycling up to 1000 cycles. A discharge capacity of 134 mAh g−1 is obtained at a high current density of 600 mA g−1, and the electrode recovers a capacity of 230 mAh g−1 when the current density is reset to 15 mA g−1 after deep cycling, thus demonstrating the excellent stability of the electrode with sodium de/intercalation. The successful use of the RGO electrode demonstrated in this study is expected to facilitate the emergence of low-cost and sustainable carbon-based materials for SIB cathode applications.

1D nanobar-like LiNi0.4Co0.2Mn0.4O2 as a stable cathode material for lithium-ion batteries with superior long-term capacity retention and high rate capability

In this work is reported the successful synthesis of 1D nanobar-like LiNi0.4Co0.2Mn0.4O2 (N-NCM), preferentially exposing the {010} electrochemically active facets.

Green synthesis of a Se/HPCF–rGO composite for Li–Se batteries with excellent long-term cycling performance

A Se/HPCF–rGO composite was synthesized as a highly stable cathode material for Li–Se batteries.

An Iodine Quantum Dots Based Rechargeable Sodium–Iodine Battery

Rechargeable sodium–iodine batteries represent a promising scalable electrochemical energy storage alternative as sodium and iodine are both low cost and widely abundant elements. Here, the authors demonstrate a rechargeable sodium–iodine battery that employs free‐standing iodine quantum dots (IQDs) decorated reduced graphene oxide (IQDs@RGO) as the cathode. Consistent with the density functional theory the authors find the Na+ ions to intercalate into the I unit cell forming stable NaI, and the battery exhibits high capacity, outstanding cycle stability (with a reversible specific capacity of 141 mA h g−1 after 500 cycles at current density of 100 mA g−1), and high rate performance (170, 146, 127, 112, and 95 mA h g−1 at current densities of 100, 200, 400, 600, and 1000 mA g−1, respectively). The reversible reactions, I2/I3 − and I3 −/I− redox couples on insertion of Na+ ions, are confirmed via in situ Raman spectroscopy. Notably, even after 500 cycles the morphology and structure of the IQDs exhibit no noticeable change implying their use as a stable cathode material for sodium–iodine batteries. Moreover, the IQDs based flexible full‐cells also exhibit high capacity and long cycle life (the capacity with 123 mA h g−1 at current density of 100 mA g−1 after 100 cycles).

Template-Engaged Synthesis of 1D Hierarchical Chainlike LiCoO2 Cathode Materials with Enhanced High-Voltage Lithium Storage Capabilities.

A novel 1D hierarchical chainlike LiCoO2 organized by flake-shaped primary particles is synthesized via a facile template-engaged strategy by using CoC2O4·2H2O as a self-sacrificial template obtained from a simple coprecipitation method. The resultant LiCoO2 has a well-built hierarchical structure, consisting of secondary micrometer-sized chains and sub-micrometer-sized primary flakes, while these primary LiCoO2 flakes have specifically exposed fast-Li(+)-diffused active {010} facets. Owing to this unique hierarchical structure, the chainlike LiCoO2 serves as a stable cathode material for lithium-ion batteries (LIBs) operated at a high cutoff voltage up to 4.5 V, enabling highly reversible capacity, remarkable rate performance, and long-term cycle life. Specifically, the chainlike LiCoO2 can deliver a reversible discharge capacity as high as 168, 156, 150, and 120 mAh g(-1) under the current density of 0.1, 0.5, 1, and 5 C, respectively, while about 85% retention of the initial capacity can be retained after 200 cycles under 1 C at room temperature. Moreover, the chainlike LiCoO2 also shows an excellent cycling stability at a wide operating temperature range, showing the capacity retention of ∼73% after 200 cycles at 55 °C and of ∼68% after 50 cycles at -10 °C, respectively. The work described here suggests the great potential of the hierarchical chainlike LiCoO2 as high-voltage cathode materials aimed toward developing advanced LIBs with high energy density and power density.

Inverse vulcanization of sulfur with divinylbenzene: Stable and easy processable cathode material for lithium-sulfur batteries

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.

High rate and thermally stable Mn-rich concentration-gradient layered oxide microsphere cathodes for lithium-ion batteries

With the aim to develop high rate and thermally stable cathode materials as potential alternatives for spinel-type LiMn2O4 and layered LiNi1/3Co1/3Mn1/3O2, monodispersed porous gradient microspheres with a well-developed layered crystal structure (total composition being close to LiNi0.2Co0.3Mn0.5O2) are successfully prepared in this work. The preparation mechanism and the effect of L-ascorbic acid on the morphology, composition, crystal structures of carbonate precursors, intermediate oxides and the electrochemical properties of LiNi0.2Co0.3Mn0.5O2 are succinctly discussed. Benefiting from the unique morphology and gradient composition distribution, both cathode materials newly developed by using carbonate precursors prepared without and with L-ascorbic acid (namely LNCMO and LNCMO-VC, respectively), exhibit excellent rate capabilities, cyclic and thermal stability. Particularly, the cell based on LNCMO-VC delivers an initial discharge capacity of about 136, 129, 122 and 89mAhg−1 and retained 95.5%, 89.4%, 85.4% and 76.1% of its initial capacity after 100 cycles at a current density corresponding to 0.5C, 1C, 2C and 5C within a voltage window of 3–4.3V (1C=278mAhg−1), respectively.

Boron Substituted Na3V2(P1-x B x O4)3 Cathode Materials with Enhanced Performance for Sodium-Ion Batteries.

The development of excellent performance of Na‐ion batteries remains great challenge owing to the poor stability and sluggish kinetics of cathode materials. Herein, B substituted Na3V2P3 –xBxO12 (0 ≤ x ≤ 1) as stable cathode materials for Na‐ion battery is presented. A combined experimental and theoretical investigations on Na3V2P3 –xBxO12 (0 ≤ x ≤ 1) are undertaken to reveal the evolution of crystal and electronic structures and Na storage properties associated with various concentration of B. X‐ray diffraction results indicate that the crystal structure of Na3V2P3 –xBxO12 (0 ≤ x ≤ 1/3) consisted of rhombohedral Na3V2(PO4)3 with tiny shrinkage of crystal lattice. X‐ray absorption spectra and the calculated crystal structures all suggest that the detailed local structural distortion of substituted materials originates from the slight reduction of V–O distances. Na3V2P3‐1/6B1/6O12 significantly enhances the structural stability and electrochemical performance, giving remarkable enhanced capacity of 100 and 70 mAh g−1 when the C‐rate increases to 5 C and 10 C. Spin‐polarized density functional theory (DFT) calculation reveals that, as compared with the pristine Na3V2(PO4)3, the superior electrochemical performance of the substituted materials can be attributed to the emergence of new boundary states near the band gap, lower Na+ diffusion energy barriers, and higher structure stability.

Identifying the Origin of Stability of Cathode Materials with Al3+-Based Surface Modifications: Amorphous Al2O3 or Crystalline LiAlxCo1-XO2?

Chemical degradation at electrode/electrolyte interfaces in Li-ion batteries creates the challenge of designing stable cathode materials to avoid the loss of active cathode material at the interface of the cathode and electrolyte. Surface modification with non-active oxide is regarded as a valid strategy to decrease such degradation based on their role as electronic insulator between cathode and electrolyte. Although different oxides have been reported to enhance stability against chemical degradation, the realization of stability and durability of surface modified cathode materials is not well understood owing to the inhomogeneity and complex morphology of typical cathode powders and the resulting difficulty in properly characterizing the surface structure. Indeed, the specific chemical identity of the non-active oxide on the surface of cathode materials can vary. For instance, Al3+ can incorporate as amorphous Al2O3 or crystalline LiAlxCo1-xO2, among others. Herein, we directly synthesized well-defined LiCoO2 (LCO) nanocrystals with a hydrothermal process and employed as model cathode materials before coating 2nm uniform Al3+ oxide thin films on their surface and annealed at different temperatures. Phase analysis have confirmed that Al can be formed as Al2O3 at low temperature and as LiAlxCo1-xO2 at high temperature. Microscopy analysis presents direct proof of Al conformally coated on their surface. The electrochemical properties have demonstrated the different effect of coating with different Al-containing phases. Compared to bare LCO nanoplates, amorphous Al2O3 film coated on such nanoplates presents higher capacity and average stability whereas LiAlxCo1-xO2 coated film have much higher stability with average capacity. Data from atomic resolution TEM and solid state NMR will be discussed.