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. IntroductionSignifi cant research effort has been devoted to novel electrodes for Li-ion batteries in recent years due to its high potential impact on energy storage for electric vehicles (EVs) and portable electronics. Li-ion batteries have already become the battery of choice for portable electronics and EVs due to their high energy density and decreasing cost. However, they are also often a limiting factor. Li-ion batteries often make up a large portion of the mass and volume of portable electronics and still limit their available energy, thus requiring frequent recharging. Currently, battery-powered EVs either offer a small driving range or are expensive due to the high price tag of Li-ion batteries. An increase in battery energy density, particularly volumetric energy density, can greatly improve and expand the possibilities of portable electronics. If similar production expenses per unit cell, and thus a lower cost per unit energy, is achieved at the same time, higher range and more affordable EVs can be produced.In order to address the market needs of reduced cost and improved energy density, many researchers have aimed to improve volumetric capacity of anodes and cathodes. High-capacity anode research, in particular, has been extremely active, and materials such as silicon (Si), silicon oxide (SiO x ), tin (Sn), and tin oxides (SnO x ) have received enormous attention, while many other, sometimes more exotic materials, have appeared in literature as well. This review is an attempt to provide a general overview of high-capacity anode materials and to develop a broader understanding of the scientifi c explorations in the fi eld of high-capacity Li-ion anodes. A detailed and comprehensive review is not attempted, and there are no doubt topics and groups of publications, which we will inevitably overlook. However, the greatest effort is made to cover the entire periodic table, and to review the various innovations in electrode architecture and chemistry, which can dramatically improve anode capacity.A traditional high-capacity Li-ion battery is made from a lithium cobalt oxide (LiCoO 2 often called LCO) cathode and a graphite (C) anode. Both electrodes are produced from active (Liion storing) powders mixed with a small content (3-5 wt%) of a polymer binder (mostly polyvinylidene fl uoride, PVDF) and a small content (1-5 wt%) of conductive carbon additives (mostly carbon black, but on occasion, vapor grown carbon fi bers or multi-walled carbon nanotubes, MWCNTs) and casted on both sides of metal current collector foils (an aluminum, Al, foil for a cathode and a copper, Cu, foil for an anode). A typical thickness of an electrode layer ranges from 60 to 100 μ m on each side of a foil. In a battery, the electrodes are separated with a porous electrically insulated membrane with a typical thickness of 15-25 μ m. By using higher capacity active materials and/or designing a structure/material that obviates/reduces the need for a separator membrane, binders, conductive additives, or current collectors, the overall ...

Mesio-temporal lobe epilepsy (MTLE) is often accompanied by granule cell dispersion (GCD), a widening of the granule cell layer. The molecular determinants of GCD are poorly understood. Here, we used an animal model to study whether GCD results from an increased dentate neurogenesis associated with an abnormal migration of the newly generated granule cells. Adult mice were given intrahippocampal injections of kainate (KA) known to induce focal epileptic seizures and GCD, comparable to the changes observed in human MTLE. Ipsilateral GCD progressively developed after KA injection and was paralleled by a gradual decrease in the expression of doublecortin, a marker of newly generated granule cells, in the dentate subgranular layer. Staining with Fluoro-Jade B revealed little cell degeneration in the subgranular layer on the KA-injected side. Labeling with bromodeoxyuridine showed an early, transient increase in mitotic activity in the dentate gyrus of the KA-injected hippocampus that gave rise to microglial cells and astrocytes but not to new neurons. Moreover, at later time points, there was a virtually complete cessation of mitotic activity in the injected hippocampus (where GCD continued to develop), but not on the contralateral side (where no GCD was observed). Finally, a significant decrease in reelin mRNA synthesis in the injected hippocampus paralleled the development of GCD, and neutralization of reelin by application of the CR-50 antibody induced GCD. These results show that GCD does not result from increased neurogenesis but reflects a displacement of mature granule cells, most likely caused by a local reelin deficiency.

Lithium Iodide (LiI) is reported as a promising electrolyte additive for lithium-sulfur batteries. It induces formation of Li-ion-permeable protective coatings on both positive and negative electrodes, which prevent the dissolution of polysulfides on the cathode and reduction of polysulfides on the anode. In addition to enhancing the cell cycle stability, LiI addition also decreases the cell overpotential and voltage hysteresis.

Development of sulfur cathodes with 100% coulombic efficiency (CE) and good cycle stability remains challenging due to the polysulfide dissolution in electrolytes. Here, it is demonstrated that electrochemical reduction of lithium bis(fluorosulfonyl)imide (LiFSI) based electrolytes at a potential close to the sulfur cathode operation forms in situ protective coating on both cathode and anode surfaces. Quantum chemistry studies suggest the coating formation is initiated by the FSI(‐F) anion radicals generated during electrolyte reduction. Such a reduction additionally results in the formation of LiF. Accelerated cycle stability tests at 60 °C in a very simple electrolyte (LiFSI in dimethoxyethane with no additives) show an average CE approaching 100.0% over 1000 cycles with a capacity decay less than 0.013% per cycle after stabilization. Such a remarkable performance suggests a great promise of both an in situ formation of protective solid electrolyte coatings to avoid unwanted side reactions and the use of a LiFSI salt for this purpose.

Lithium-metal fl uoride (MF) batteries offer the highest theoretical energy density, exceeding that of the sulfur-lithium cells. However, conversion-type MF cathodes suffer from high resistance, small capacity utilization at room temperature, irreversible structural changes, and rapid capacity fading with cycling. In this study, the successful application of the approach to overcome such limitations and dramatically enhance electrochemical performance of Li-MF cells is reported. By using iron fl uoride (FeF 2 ) as an example, Li-MF cells capable of achieving near-theoretical capacity utilization are shown when MF is infi ltrated into the carbon mesopores. Most importantly, the ability of electrolytes based on the lithium bis(fl uorosulfonyl)imide (LiFSI) salt is presented to successfully prevent the cathode dissolution and leaching via in situ formation of a Li ion permeable protective surface layer. This layer forms as a result of electrolyte reduction/oxidation reactions during the fi rst cycle of the conversion reaction, thus minimizing the capacity losses during cycling. Postmortem analysis shows the absence of Li dendrites, which is important for safer use of Li metal anodes. As a result, Li-FeF 2 cells demonstrate over 1000 stable cycles. Quantum chemistry calculations and postmortem analysis provide insights into the mechanisms of the passivation layer formation and the performance boost.

A hierarchical particle-shell architecture for long-term cycle stability of Li2S cathodes is described. Multiscale and multilevel protection prevents mechanical degradation and polysulfide dissolution in lithium-sulfur battery chemistries.

Transition metal fluorides (MFx ) offer remarkably high theoretical energy density. However, the low cycling stability, low electrical and ionic conductivity of metal fluorides have severely limited their applications as conversion-type cathode materials for lithium ion batteries. Here, a scalable and low-cost strategy is reported on the fabrication of multifunctional cobalt fluoride/carbon nanotube nonwoven fabric nanocomposite, which demonstrates a combination of high capacity (near-theoretical, 550mAhgCoF2-1) and excellent mechanical properties. Its strength and modulus of toughness exceed that of many aluminum alloys, cast iron, and other structural materials, fulfilling the use of MFx -based materials in batteries with load-bearing capabilities. In the course of this study, cathode dissolution in conventional electrolytes has been discovered as the main reason that leads to the rapid growth of the solid electrolyte interphase layer and attributes to rapid cell degradation. And such largely overlooked degradation mechanism is overcome by utilizing electrolyte comprising a fluorinated solvent, which forms a protective ionically conductive layer on the cathode and anode surfaces. With this approach, 93% capacity retention is achieved after 200 cycles at the current density of 100 mA g(-1) and over 50% after 10 000 cycles at the current density of 1000 mA g(-1) .