Lithium Source Research Articles

7Li evolution in the thin and thick discs of the Milky Way

Recent detection of the isotope $^7$Be (that decays into $^7$Li) in the outburst of classical novae confirms the suggestion made in the 70s that novae could make $^7$Li. We reconsidered the role of novae as producers of Li by means of a detailed model of the chemical evolution of the Milky Way. We showed that novae could be the Galactic lithium source accounting for the observed increase of Li abundances in the thin disk with stellar metallicity. The best agreement with the upper envelope of the observed Li abundances is obtained for a delay time of ~ 1 Gyr for the nova production and for an effective Li yield of $1.8 (\pm 0.6) \times 10^{-5}$ $M_{\odot}$ over the whole nova life. Lithium in halo stars is depleted by ~ 0.35 dex, assuming the pristine abundance from standard big bang nucleosynthesis. We elaborate a model that matches the pristine stellar abundances, assuming that all stars are depleted by 0.35 dex. In this case, the delay remains the same, but the Li yields are doubled compared to the previous case. This model also has the merit to match the Li abundance in meteorites and young TTauri stars. The thick disk model, adopting the parameters derived for the thin disk, can also explain the absence of increase of Li abundances in its stars. The thick disk is old, but formed and evolved in a time shorter than that required by novae to contribute significantly to Li. Therefore, no Li enhancement is expected in thick disk stars. We show that the almost constant Li abundance in the thick disk results from the compensation of stellar astration by spallation processes.

Synthesis and electrochemical performance of a nanocrystalline Li4Ti5O12/C composite for lithium-ion batteries prepared using resorcinol–formaldehyde resins

Recently, spinel lithium titanate (Li4Ti5O12, LTO) has attracted attention as an anode material for lithium-ion batteries (LIBs). However, the poor electronic conductivity and low lithium-ion diffusion coefficient of LTO suppresses its electrochemical performance during quick charging. One possible way to improve the electrochemical performance is to reduce the LTO particle size to the nanometer range and modify the surface conductivity. In this study, LTO/C was synthesized by a one-step carbonization route without any specialized equipment using a resorcinol–formaldehyde (RF) resin as a carbon source, lithium acetate as a lithium source and polymerization catalyst, and commercial nano-sized TiO2 as a titanium source. The homogeneous mixing of the RF resin dissolved in water led to the uniform dispersion of the TiO2 and the Li source. The polymerization of the RF resin, TiO2, and dissolved Li source formed a closely structured matrix. LTO/C is comprised of crystalline LTO covered by a thin carbon layer. The RF resin plays an essential role in producing a suitable reaction field, preventing grain growth, and controlling the LTO primary particle size. The specific capacities of the LTO/C composite (carbon 15 wt%, carbonized at 900 °C) are 161 and 90 mAh/g at 0.1C and 25C, respectively. The composite shows improved electrochemical properties compared to commercial LTO.

Mixed‐Valent Europium in the Cubic Thiosilicate Li3Eu6[SiS4]4

In an attempt to synthesize LiEu3S3[SiS4] utilizing elemental europium and sulfur as well as SiS2 and an excess of LiCl as flux and lithium source, dark red, platelet‐shaped single crystals of Li3Eu6[SiS4]4 were obtained. This new compound crystallizes in the cubic space group I43d (a = 1369.22(5) pm) with four formula units per unit cell. Both the Li+ and the Si4+ cations are surrounded by four sulfide anions. The [SiS4]4– tetrahedra show merely a slight trigonal distortion, while the [LiS4]7– units are best described as flattened bisphenoids. The europium cations exhibit an eightfold, rather irregular coordination environment by eight S2– anions and have to be regarded mixed‐valent with a +2:+3 charge‐ratio of 5:1 in order to gain electroneutrality. The lack of an inversion center is caused by the [SiS4]4– tetrahedra being stacked exclusively top up along [111] in this acentric crystal structure.

Synthesis of Metal–Organic Framework Materials by Reflux: A Faster and Greener Pathway to Achieve Super-Hydrophobicity and Photocatalytic Application

In this contribution, reflux was demonstrated to be a faster and greener pathway in the synthesis of heterometallic metal–organic frameworks (MOFs) [Li2Sn2(BDC)3(H2O)2]n (LiSn; H2BDC = 1,4-benzenedicarboxylic acid). By means of this method, LiSn solid materials with various particle sizes and surface morphologies were achieved by simply changing the lithium sources (LiOH, 1, and LiNO3, 2). During the reflux process, the precursors were prone to grow from polyhedral LiSn materials, of which the LiOH was preferable to produce uniformly dispersed LiSn-1 nanoparticles with smaller sizes. These as-prepared LiSn materials possess good thermal stability proven by maintaining their structural crystallinity up to 250 °C. UV–vis diffuse reflectance spectroscopy suggested band gap energies (Eg) of 3.14 and 2.96 eV for LiSn-1 and LiSn-2, respectively, indicating the potential photocatalytic ability of these materials. Visible-light-driven degradation of methyl orange, methylene blue, and rhodamine B showing a higher photocatalytic performance in the presence of LiSn revealed high photocatalytic activity based on a first order kinetic study. Moreover, the LiSn-coated films resulted in the generation of hydrophobic substrate surfaces due to their specific hierarchy hills-and-valley type surface terrain with lotus leaf effects. Of special notice is the LiSn-1-coated stainless steel mesh and 200-mesh filter cloth showing magnificent oil–water separation property. This study discovered a family of bifunctional LiSn materials with both photocatalytic activity and super-hydrophobicity, showing great promise in water purification applications.

Effect of the Electrolyte on the Cycling Efficiency of Lithium-Limited Cells and their Morphology Studied Through in Situ Optical Imaging

Capacity retention of anode-free cells, in which the cathode’s lithium was the sole lithium source, was studied. These cells fail by depletion of their limited amount of cycling lithium, unlike cells with lithium foil anodes in which the buildup of an insulating, dead lithium layer on the anodes causes failure. The electrolyte dependence of the deposition morphologies was also studied optically in a symmetrical cell built with lithium electrodes. After passage of 28 mAh cm–2, dendrite-free deposits were observed in a concentrated LiNO3 electrolyte. SEI characterization revealed that this LiNO3 concentrated electrolyte formed a Li2O enriched and organic polymer depleted interphase.

Associated petroleum waters, as a promising source of lithium

In this paper we attempted to estimate the size of mineral resources that are poor in lithium content Due to possible depletion of existing resources poor resources can become the most promising source of resources Possible directions and prospects f lithium extraction from poor sources of raw materials which are underground waters associated oil waters The directions for solving these problems are continued Nowadays hydro mineral raw materials gradually become the main source of lithium In view of complexity of the salt composition of hydro mineral raw materials the use of highly selective inorganic ion exchange materials is the most promising method for recovery of lithium

Global Lithium Sources—Industrial Use and Future in the Electric Vehicle Industry: A Review

Lithium is a key component in green energy storage technologies and is rapidly becoming a metal of crucial importance to the European Union. The different industrial uses of lithium are discussed in this review along with a compilation of the locations of the main geological sources of lithium. An emphasis is placed on lithium’s use in lithium ion batteries and their use in the electric vehicle industry. The electric vehicle market is driving new demand for lithium resources. The expected scale-up in this sector will put pressure on current lithium supplies. The European Union has a burgeoning demand for lithium and is the second largest consumer of lithium resources. Currently, only 1–2% of worldwide lithium is produced in the European Union (Portugal). There are several lithium mineralisations scattered across Europe, the majority of which are currently undergoing mining feasibility studies. The increasing cost of lithium is driving a new global mining boom and should see many of Europe’s mineralisation’s becoming economic. The information given in this paper is a source of contextual information that can be used to support the European Union’s drive towards a low carbon economy and to develop the field of research.

Improving the Cycling Stability of Sodium Metal Electrode By Making an Sodium-Carbon Composite Electrode

The use of metallic anodes such as lithium and sodium has attracted large attention in the battery field because of their extremely high specific capacity and low operation potential. Indeed, the formation of metal dendrite upon repeated electrochemical plating/stripping cycling was early identified as obstacle of the development of safe metal anode secondary batteries. Also, due to dendrite formation, the low cycle efficiency and unstable cycle life happen, which hinder their practical application as anode materials. Therefore, to suppress the growth of metal dendrite is one of the most critical issues from a practical view point. Recently, lithium metal has been extensively researched as anode candidate for secondary batteries due to its lowest redox potential and highest specific capacity among metallic anodes. Despite these promising properties, lithium sources are relatively limited and unevenly distributed across the globe, which lead to high costs of lithium metal batteries. Therefore, inevitably, lithium-based batteries will become unaffordable and large-scale production will falter. Therefore, sodium (Na) is one of the promising alternatives to lithium for energy storage technologies because of its relatively high theoretical specific capacity of 1166 mAh g-1 and natural abundance. Also, it has comparable redox potential, that is -2.70 V vs. SHE. However, like lithium metal anode, inhomogeneous electrochemical deposition of Na is a crucial problem that have to be solved for the usage of sodium metal as anode safely. Furthermore, Na metal has extremely high reactivity with liquid organic electrolyte, so high interfacial resistance could be induced due to continuous electrolyte decomposition during battery cycling, which also leads to earlier cell failure. In this research, we present a stabilized sodium electrode by introducing electrically connected carbon network (ECN) to a bulk Na electrode with a simple folding & rolling method. As a results of introducing ECN, we observed that a cell overpotential was decreased as the amount of ECN inside bulk Na metal was increased. Also, we found that the cycling stability of Na/Na symmetric cell with ECN was almost 4.5 times increased compared to bare Na/Na cell, which is consistent with the results of EIS during cycling. By using SEM and CA analysis, we confirmed that an introduced ECN could act as not only an electrical network but also artificial uniform seed for Na nucleation.

SLMP® for Pre-Lithiation and Ultra-Thin Lithium Foil Anode Applications

Due to low first cycle coulombic efficiency, pre-lithiation techniques are accepted as a necessary enabling technology for high energy anodes such as Si/C composite materials. An independent source of active lithium can be combined electrochemically, chemically or physically with the anode to partially pre-lithiate and reduce first cycle inefficiency therefore increasing cathode utilization. (1) Electrochemical, ex-situ techniques, for example, roll-to-roll electrochemical baths and other techniques, including oversized cathode, lithium rich cathodes, sacrificial salts or in line short circuiting have been proposed. Among the physical techniques are vacuum deposition, sputtering, thermal spraying, and mechanical milling. (1) However, to-date, chemical pre-lithiation techniques have shown the most promise. Specifically, the ex-situ addition of metallic lithium to the anode material. The use of FMC’s advanced material, Lectro® Max Powder (SLMP) has been demonstrated worldwide as an effective and efficient pre-lithiation material. (1),(2),(3) SLMP can deliver capacity close to the theoretical lithium capacity of 3860 mAh/g and, after addition of the electrolyte, reacts with the anode material in-situ, and thus exists in the lithium ion form in the cell. (3) Because of its high capacity, addition of SLMP causes negligible increase in cell mass or volume unlike the case of sacrificial salts or oversized cathode use, which deliver lower capacity per unit mass and leave inactive phases after lithium extraction which might lower overall energy density of the cell. (1) In addition to use as a pre-lithiation agent to enable high energy anode materials SLMP could also be used to fully lithiate anode materials and thus allow the use of new cathode materials. (4) Most of beyond lithium ion chemistries and next generation lithium ion chemistries will require thin lithium metal anode use to achieve targeted volumetric energy density. Today, production of thin lithium foil involves extrusion of lithium metal followed by rolling to achieve desired thinness, which is complicated and expensive; thus, no commercially viable source of thin foil exists. SLMP-derived thin Li foil offers the possibility of achieving thin foil with width being limited only by the substrate used. In this work, we show the effectiveness of SLMP in improving the performance of commercially available silicon-based anode material. The anode composition is 85% SiO/C composite material and 15% Polyimide binder. The cathode composition is LiCoO2 (90%) + carbon black (5%) + PVdF (5%). Surface application technique was used to apply SLMP slurry onto the surface of prefabricated SiO electrodes. Single layer pouch SiO/LiCoO2 cells were assembled and 1M LiPF6 /EC+DEC (1:1) was used as the electrolyte. The pouch cells were conditioned at room temperature for 24 hours before the battery test. The pouch cell test protocol was: constant current charge at C/10 to 4.3 V, constant voltage charge at 4.3 V to C/100; constant current discharge at C/10 to 3.0 V. SLMP utilization has been evaluated based on its ability to compensate first cycle irreversible capacity. Figure 1 below shows the effect of SLMP on first cycle efficiency of SiO/LiCoO2 pouch cells. One of the important properties of SLMP is its specific capacity. SLMP contains at least 97% metallic lithium which can be fully utilized. To demonstrate this, an electrochemical system has been designed to test SLMP’s capacity, Li/Electrolyte/SLMP+Cu. About 1 mg of SLMP was deposited onto a half-inch Cu disc using a slurry of SLMP. After the solvent was fully evaporated, the electrode was calendered using 12,000 lbs pressure creating SLMP-derived thin Li foil. The electrodes were used to assemble coin cells with lithium foil counter electrode. 1M LiPF6/EC+DEC was used as the electrolyte. The cells were charged at 0.1 mA to 3.0 V. Figure 2 shows the voltage profiles for the cells comprised of SLMP-derived thin foil. The voltage profiles and the SLMP capacity are reproducible. Close to theoretical lithium capacity can be extracted from the SLMP derived thin foil. We will also discuss a novel SLMP delivery system which can be used at commercial scale to safely and economically incorporate SLMP into existing LIB systems as well as being used to produce ultra-thin lithium foil for solid state lithium applications. References Florian Holtstiege, Peer Bärmann, Roman Nölle, Martin Winter, and Tobias Placke, Pre-Lithiation Strategies for Rechargeable Energy Storage Technologies: Concepts, Promises and Challenges, Batteries 2018, 491), 4Margret Wohlfahrt-Mehrens, Manuel Weinberger, Novel strategies towards the realization of larger lithium sulfur/silicon pouch cells. Electrochimica Acta, Volume 191, 10, February (2016), p. 124–132.Y. Li, B. Fitch, Electrochem. Commun., 13, (2011) 664.K.B. Fitch, M.V. Yakovleva, Y. Li, I. Plitz, A. Skrzypczak, F. Badway, G.G. Amatucci, and Y. Gao, ECS Transaction 2007 Figure 1

Electrochemical Performance of Sodium Polymer Battery Employing Polyurethane-Based Gel Polymer Electrolyte

With limited amounts of fossil fuels and increasing demand for efficient energy management, lithium-ion batteries (LIBs) have been a leading power source for hybrid electric vehicles and large-scale energy storage systems. However, rising price of lithium sources has become a significant concern, caused by increasing market demand for lithium and limited amounts of lithium resources. In this respect, sodium-based batteries have been considered an alternative to the LIBs due to the abundance of sodium resources in nature.1 Like LIBs, enhancing the battery safety is a significant concern, because use of highly flammable organic solvents may trigger safety problems. Gel polymer electrolytes present many potential advantages, including enhanced safety, good interfacial contact, easy processing to make thin film and flexibility in the battery design, as compared to conventional separators.2 In this study, we prepared polyurethane (PU)-based gel polymer electrolyte (GPE) composed of PU polymer matrix and sodium-ion liquid electrolyte, which exhibited good compatibility with liquid electrolyte and superior electrochemical properties. The PU GPE was employed to assemble the Na/Na3V2(PO4)3 cells. Electrochemical performance of the sodium cells was enhanced by employing the PU GPE. References M.D. Slater, D. Kim, E. Lee and C.S. Johnson, Adv. Funct. Mater., 23, 947-958 (2013).H. Gao, B. Guo, J. Song, K. Park and J.B. Goodenough, Adv. Energy Mater., 5, 1402235 (2015). Figure 1

Deep Red Phosphors Based on 3d Transition Metals for Energy Conversion from UV to Visible Rays

Reflecting the recent increasing concern about an energy issue, solar cells have been developing for several decades. Silicon is the major solar cell material with the band gap energy of ~1.17 eV. The optical absorption band corresponds to ~1100 nm and the radiations with wavelengths shorter than it are absorbed to generate photovoltaic power. The spectral sensitivity characteristics do not match the solar spectrum and energy conversion of the UV and blue radiations to longer wavelength side will improve further the efficiency of the Si solar cells. This work presents deep-red phosphors based on lithium aluminates and related compounds using 3d transition metals as the luminescent center. Deep-red emission by 3d transition metal phosphors has been much attracted because it can be attained with quite few rare-earth phosphors. LiAlO2 and LiAl5O8 were chosen for phosphor host materials, which were prepared through a solid state reaction method from lithium and aluminum sources of LiF and Al2O3. The luminescent center of Fe3+ or Mn4+ was added in a form of Fe(NO3)3·9H2O or MnO2. The mixed powder in a Pt crucible was heat treated in air at 800-1300 °C. It was found that the lithium source LiF brought several unusual phases in the products. Metastable α-LiAlO2 appeared at 800 °C and below when a mixture of LiF and Al2O3 was treated with an excess a LiF condition of LiF/Al = 3. It was good contrast to the fact that the a-phase obscurely crystalizes at 500-700°C with the broad peaks when LiOH·H2O was used as a lithium source. α-LiAlO2 transformed to stable γ-LiAlO2 at 800 °C or above. On the other hand, a mixture at LiF : Al2O3 = 1 : 2 resulted in a novel host material with an unknown composition. Although the XRD pattern itself has been reported as JCPDS #38-610, the details of the crystal structure and the actual composition have never been disclosed. The composition estimated in this work with EDS and XPS was Al4LiF0.1O6.45. A disordered spinel structure was assigned for ALFO by Rietveld analysis. The luminescent spectra are compared among α-LiAlO2:Fe3+, γ-LiAlO2:Fe3+ and ALFO:Fe3+ in Fig. 1, and between LiAl5O8:Mn4+ and ALFO:Mn4+ in Fig. 2. α-LiAlO2:Fe3+, γ-LiAlO2:Fe3+ and ALFO:Fe3+ showed rather broad PL with the peak tops between 650 and 800 nm. Their peak positions are slightly different to each other and the emission peak of ALFO:Fe3+ resides at the shortest wavelength side. The excitation bands are in the UV region and the maxima are around 250 nm. On the contrary, the Mn4+ luminescent center changes its properties depending on the host materials. Deep red emission at 661 nm was much enhanced in ALFO:Mn4+, whereas LiAl5O8:Mn4+ exhibited only faint PL. Acknowledgement: This work was performed under the Cooperative Research Program of "Network Joint Research Center for Materials and Devices (20181151). Figure 1

An event-triggered coincidence algorithm for fast-neutron multiplicity assay corrected for cross-talk and photon breakthrough

A model quantifying detector cross-talk and the misidentification of events in fast neutron coincidence distributions is described. This is demonstrated for two experimental arrangements comprising rings of 8 and 15 organic liquid scintillation detectors. Correction terms developed as part of this model are tested with 252Cf and a relationship is developed between the 235U enrichment of U3O8 and the order of correlated, fast neutron multiplets induced by an americium–lithium source. The model is also supported by Geant4 simulations. The results suggest that a typical assay, for experimental arrangements that are similar to the examples investigated in this research, will exhibit cross-talk for less than 1% of all detected fast neutrons but, if not accounted for, this can bias the numerical analysis by a margin of 10% and 35% in second- and third-order coincidences (i.e. couplet and triplet counts), respectively. Further, for the case of 252Cf, it is shown that a relatively low proportion of 4% breakthrough by γ rays (that is, photons misidentified as neutrons by the pulse-shape discrimination process) can lead to an erroneous increase of 20% in total neutron counts in the assay of a mixed-field, in this case of 252Cf. These findings will help direct the developments needed to enable organic scintillation detectors with pulse shape discriminators to be applied reliably to nuclear safeguards and non-proliferation verification tasks.

LITHIUM: RESOURCES, PRODUCTION AND PROSPECTS OF WORLD MARKET DEVELOPMENT

The paper deals with lithium which is currently characterized by one of the fastest growth rates in terms of price, consumption and production volumes. We have estimated the rates of consumption, the growth in production volumes and the growth of the explored volumes of lithium mineral resources and have given forecast of development of the world lithium market, growth of lithium production and price dynamics. Thus, the increase in world production of lithium by 2020 should exceed 12,000 tons per year. The increase in the consumption of lithium is shown to stimulate the growth of geological exploration of its mineral resources and to lead to a sharp increase in the explored lithium reserves. Moreover, we have attempted to evaluate other lithium mineral resources including those with a low content of lithium. The analysis demonstrate that, in accordance with existing technologies and speed of the lithium production growth, lithium ore will run out in about 25 years, and lithium reserves of proven resources associated with salt lakes will be depleted in about 50 years. The paper suggests several ways of solving this problem. The first one is an increase in the extraction of lithium from existing sources of raw materials, that is, the use of more effective methods. The second one is the use of lean lithium resources, such as underground brines and associated oil waters which can become the most promising source of lithium (the possible directions and prospects of extraction have been shown). The third way is the use of secondary lithium resources and the processing of spent lithium batteries. Keywords: lithium; lithium market; world reserves of lithium; lithium mining; underground brines; associated oil waters.

A new developed in-between shots lithium evaporation coating system for improving plasma performance in EAST

A new in-between shots evaporative lithium coating system has been successfully developed and implemented on the Experimental Advanced Superconducting Tokamak (EAST) for the 2017 campaign. This paper describes a novel technique for the introduction of lithium into the EAST vessel allowing evaporative coatings to be applied between discharges without requiring a significant amount of time to insert and retract the lithium source. This newly designed system utilizes a rotating axis driven by a vacuum dynamic sealing feedthough under remote control to open and close a shutter. A compression bellows, which drives the delivery tube, guarantees accurate position of the oven thus avoiding possible direct contact with the plasma. This allows the new evaporation system to be operated in two distinct modes. One mode is operated in-between shots to refresh pre-coated lithium film, the other is a real-time lithium vapor injection during plasma operations to provide active wall conditioning during long pulse plasma discharges. In this paper, operation of this new lithium deposition system in the in-between shots replenishment mode is described. Initial experiments show that this system worked well during the interval of discharges in EAST, and the in-between shots lithium coating effectively reduced the wall recycling and impurity concentrations. Moreover, the application of fresh lithium coating lead to sustain the plasma stored energy and confinement, as well as a reduction of impurity radiation.

Efforts to remove aqueous lithium ion using Octolig® and methylated derivatives

ABSTRACTAqueous Li+ – containing samples (in DI water or well water) were eluted over Octolig®, a polyethylenediimine covalently attached to a high- surface-area silica gel, and only slight removal, if any, could be claimed. However, when using tetrahydrofuran (THF) as a solvent we quantitatively removed lithium ion with Octolig® or with alkylated Octolig®, demonstrating the efficacy of Octolig® and lack of advantage of a N, N′-dialkylated Octolig®. In addition, the removal of alkali metal ions (lithium, sodium, and potassium) in THF by Octolig® was partially selective: While being quantitative for lithium it was only about 40% for potassium. The study has potential implications for using geothermal brines not only as a heat source, but as a source of lithium as well.

Comparative Investigation of 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 Cathode Materials Synthesized by Using Different Lithium Sources.

Lithium-rich manganese-based cathode materials has been attracted enormous interests as one of the most promising candidates of cathode materials for next-generation lithium ion batteries because of its high theoretic capacity and low cost. In this study, 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 materials are synthesized through a solid-state reaction by using different lithium sources, and the synthesis process and the reaction mechanism are investigated in detail. The morphology, structure, and electrochemical performances of the material synthesized by using LiOH·H2O, Li2CO3, and CH3COOLi·2H2O have been analyzed by using Thermo gravimetric analysis (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 material prepared by using LiOH·H2O displays uniform morphology with nano particle and stable layer structure so that it suppresses the first cycle irreversible reaction and structure transfer, and it delivers the best electrochemical performance. The results indicate that LiOH·H2O is the best choice for the synthesis of the 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 material.

Three-dimensional Li1.2Ni0.2Mn0.6O2 cathode materials synthesized by a novel hydrothermal method for lithium-ion batteries

Three-dimensional (3D) hierarchical Li-rich Li1.2Ni0.2Mn0.6O2 microspheres are directly prepared by a novel hydrothermal method without calcination. The preparation procedure involves a co-precipitation process for precursor microspheres and subsequent hydrothermal reaction with different concentration of lithium source at 220 °C. The prepared layered materials are composed of stacked nanorods with the length of 100–200 nm. When used as cathode material of lithium-ion battery, the material synthesized by appropriate concentration of lithium source exhibits remarkable electrochemical performances with an initial discharge specific capacity of 269 mA h g−1 and a first Coulombic efficiency of 82.8% at 0.1 C. Meanwhile, a high reversible specific capacity of 121.3 mA h g−1 can be achieved after 100 cycles at 5 C, revealing the good rate capability. These results demonstrate that the direct hydrothermal method without calcination is an effective and energy-saving approach to synthesize 3D Li-rich cathode materials for lithium-ion batteries.

Abnormal Self-Discharge in Lithium-Ion Batteries

Lithium-ion batteries are expected to serve as a key technology for large-scale energy storage systems (ESSs), which will help satisfy recent increasing demands for renewable energy utilization. Besides their promising electrochemical performance, the low self-discharge rate (<5% of the stored capacity over 1 month) of lithium-ion batteries is one of their most significant advantages for ESSs. Herein, contrary to conventional belief, we report that the self-discharge of LIBs can be abnormally accelerated when the battery had been exposed even to a routine short-term thermal exposure. We demonstrate that, this thermal ‘history’ in addition to the temperature itself is memorized in the battery and accelerates the self-discharge rate. The series of characterizations performed in our work reveal that the electrolyte salt acts as a strong oxidizing agent by vigorously damaging the surface of the cathode, producing an internal ‘parasitic’ lithium source that continuously supplies lithium for the self-discharge. Although it is widely known that battery operation at elevated temperature generally induces faster degradation of capacity over cycles, the key finding here is that not only the operation temperature but also the ‘thermal history’ of the battery should be carefully considered because this history remains and continues to affect the self-discharge rate afterwards. The self-discharge of LIBs has remained largely neglected; however, our findings suggest that close attention must be paid to the self-discharge of LIBs applied to large-scale ESSs, which, unlike mobile electronic devices, would be exposed to various outdoor temperature conditions.

New Insights into Anionic Redox Reaction and Performance Degradation of Iron-Based Layered Oxides Cathode Materials for Sodium-Ion Batteries

Sodium ion batteries continue to be of immense interest as potential substitution for lithium-ion battery due to its abundance on earth, contrary to limited source of lithium. The beneficial effect on the cost efficiency will increase if other element in the cathode is also earth abundant materials. Many type of iron based layered oxides such as secondary, tertiary, quaternary layered cathode compound for Na ion batteries have been studied. Most of these studies showed severe loss of cycle performance at high voltage. To improve performance of iron based layered oxides, especially at high voltage region, it is necessary to better understand the redox reaction of Fe3+/Fe4+ during sodium extraction. Thus, O3 type NaFeO2 was synthesized and variety of analysis was conducted such as in-situ synchrotron hard X-ray absorption spectroscopy, ex-situ soft X-ray absorption spectroscopy, and transmission electron spectroscopy. In situ hard X-ray absorption spectra showed that Fe K-edge doesn’t shift to higher energy during Na extraction. The shift in Fe K-edge is sensitive with oxidation state of Fe that mean Fe3+/Fe4+ redox reaction does not contribute much during electrochemical test. Instead of Fe, the emerging of new peak on the pre-edge of the oxygen K-edge, indicating charge compensation of oxygen during the whole Na extraction/insertion process. Moreover, we directly reveal the limited reversibility of the oxygen redox reaction and correlation of performance degradation with surface degradation of α-NaFeO2 cathode in sodium-ion cells especially at high voltage. These finding provide more deep understanding for future development of iron-based cathode materials for sodium-ion batteries.

Synthetic Control and Structural Stabilization of Ni-Rich Layered Oxides As High-Energy Cathode Materials for Lithium Ion Batteries

Ni-rich layered oxides (LiNi1-xMxO2, M=Co, Mn, Al, etc., x<0.5) have been demonstrated as practical cathode materials for high-energy and high-power lithium ion batteries. However, various synthetic factors affect the layered structural ordering of LiNi1-xMxO2 and related electrochemical lithium storage performances. Herein, we report on developing a high-capacity Ni-rich LiNi0.8Co0.1Mn0.1O2 oxide with enhanced cycleability via the synthetic control. Systemic investigation is made to the phase evolution of LiNi0.8Co0.1Mn0.1O2 oxide under different annealing temperatures by ex-situ and in-situ synchrotron X-ray diffraction (XRD) measurements, coupled with quantitative structural analysis through refinements. Structural characterization indicates an intriguing phase transition of LiNi0.8Co0.1Mn0.1O2 from a rock-salt structure at low annealing temperatures directly to a layered α-NaFeO2-type structure with a R-3m space group at high temperatures. The in-situ XRD studies gain us access to the phase diagram in the confined Ni-rich region of the Ni-Mn-Co space, thereby enabling the design of synthetic protocols for preparing high-capacity LiNi1-x-yMnxCoyO2 oxides with stabilized structure and reasonable cycling stability. Furthermore, a preheating process and Li2TiO3 coating layer have been introduced during the synthesis of LiNi0.8Co0.1Mn0.1O2 oxide, in order to manipulate the lithium source reaction by fabricating the outer shell in advance. As a result, the resulting LiNi0.8Co0.1Mn0.1O2 cathode material reveals the higher degree of structural ordering and considerably enhanced lithium storage performances. This work offers a feasible route to optimize the layered structure of Ni-rich cathode materials via the synthetic control of the lithium source reaction, and further sheds light on the fundamental relationship between crystal structure and electrochemical performance for high-energy lithium ion batteries.