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High capacity all-solid-state Li-ion battery anodes were prepared using an industrially scalable solution coating process. Employing commercially available polyacrylonitrile as a mixed conducting binder, we have demonstrated stable cycling, high capacity electrodes with large mass loadings of tin active material. This is, to our knowledge, the first time a high capacity lithium-alloying material has been utilized in a slurry-coated sheet-style all-solid-state Li-ion battery anode. Optimization of this new electrode architecture resulted in a sheet-style anode capable of retaining an electrode specific capacity of 643.5 mAh/g after 100 charge-discharge cycles at a 0.1C rate. We believe that this work represents a step forward for slurry-coated electrodes intended for use with sulfide solid electrolytes and that the continued development of these high capacity sheet-style anodes will be critical to the commercialization of the all-solid-state Li-ion battery.

This study demonstrates the application of Si/C composite fibers as anode materials for all-solid-state lithium-ion batteries. Using polyacrylonitrile as the carbon precursor, Si/C fibers were prepared through electrospinning and subsequent heat-treating processes. To investigate the correlation between fiber diameter and electrochemical performance, we prepared three electrodes (A, B, C), containing Si/C fibers with ~2 μm, ~1 μm and ~0.1 μm diameters, respectively. Our results revealed that although the composition of all three electrodes was nearly the same, the Si/C fiber based electrodes exhibited better capacity retention when their fiber diameters were smaller. Normalized to the total mass of electrode composite, the solid-state half-cell prepared with the smallest diameter (~0.1 μm) Si/C fibers achieved a reversible specific capacity of ~700 mAh g−1 (normalized to electrode mass) over 70 cycles. We believe that this report can serve as an informative approach toward the utilization of electrospun Si/C fibers as anode materials for all-solid-state lithium-ion batteries.

Pure tin (Sn) metal nano-powder is investigated as a high capacity negative electrode for rechargeable all-solid-state Li-ion batteries. Sn is used to form a fully dense network intertwining with solid electrolyte negating necessary conductive additive. Galvanostatic cycling of the Sn composite electrode delivers a reversible capacity 800 mAh g −1 of Sn with a constant coulombic efficiency over 99.2%.Wereportontheeffectofpressureandrateuponthedelithiationmechanics,drawingcorrelationsbetweenSnvolumeincrease factors and stress accumulation over the course of Sn-Li phase transformations. Due to the fabricated electrode microstructure, we are able to operate the cell at ambient pressure conditions ‐ the next step toward commercialization of the solid-state battery. We believe that this initial work provides new opportunities to study the electrochemical expansion of Sn with the inclusion of rigid electrolyte particles. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any

In order to address the poor energy density of bulk all-solid-state lithium-ion batteries a new composite electrode preparation method is proposed. This study demonstrates the concurrent synthesis of the FeS2 active material and a glass electrolyte which is similar to the (100-x)P2S5:xLi2S system of glass electrolytes. This is accomplished through the successive mechanochemical and thermal treatments of Fe2P, S, and Li 2S. The composite electrode’s ionic conductivity of 5.46 × 10−5 Sc m −1 at 60◦C and specific energy of 1.2 Wh g −1 versus a lithium metal anode suggest that this method may provide a more intimate solid-solid interfacial contact between active material and glass electrolyte. The results of this study provide a completely new perspective on the preparation of all-solid-state composite electrodes.

Bulk all-solid-state batteries made with mechanochemically prepared Li2S-P2S5 glass-ceramic electrolytes 1‐3 are a safe alternative to conventional Li-ion batteries because sulfide based glass-ceramic electrolytes are pure ionic conductors, non-volatile, non-flammable, and stable versus lithium metal. However, the use of lithium metal anodes in all-solid-state batteries (ASSBs) is not straightforward because dendritic lithium can penetrate porous cold-compacted glassceramic electrolyte separators. To demonstrate this point, an interfacial instability that was observed by a previous study may be better characterized as an internal short. 4 To improve cell cycleability and survivability a recent study has demonstrated that the vapor deposition of thin lithium films onto Li2S-P2S5 glass-ceramic solid-state electrolyte (SSE) pellets can improve electrolyte-lithium electrode in

Cycle stability of solid-state lithium batteries (SSLBs) using a LiCoO2 cathode is improved by atomic layer deposition (ALD) on active material powder with Al2O3. SSLBs with LiCoO2/Li3.15Ge0.15P0.85S4/77.5Li2S-22.5P2S5/Li structure were constructed and tested by charge-discharge cycling at a current density of 45 μA cm−2 with a voltage window of 3.3 ~ 4.3 V (vs. Li/Li+). Capacity degradation during cycling is suppressed dramatically by employing Al2O3 ALD-coated LiCoO2 in the composite cathode. Whereas only 70% of capacity retention is achieved for uncoated LiCoO2 after 25 cycles, 90% of capacity retention is observed for LiCoO2 with ALD Al2O3 layers. Electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM) studies show that the presence of ALD Al2O3 layers on the surface of LiCoO2 reduces interfacial resistance development between LiCoO2 and solid state electrolyte (SSE) during cycling.

The automotive segment of the global lithium-ion battery market is slated for exceedingly high growth in the near future, stoking a demand for next-generation electrode materials capable of delivering the 400 Wh/kg benchmark at low-costs. While most of the recent research efforts to enable such materials focus on complex material modifications and nano-architectured electrode design, developing alternative electrolyte chemistries presents another avenue towards creating the next generation Li-ion battery. Previous work at the University of Colorado Boulder demonstrated the viability of this approach. By pairing a simple, scalable, yet robust Si electrode architecture with an imide-based room temperature ionic liquid (RTIL) electrolyte, this work enabled a Si/L333 full-cell capable of long-term cycling (>1000 cycles) at a charge-discharge rate of 1C.1 Recently an initial feasibility study has revealed the impressive compatibility of the same imide-based RTIL electrolyte with lithium-manganese-rich (LMR) layered oxides. The newly developed LMR material had the potential to revolutionize the transportation industry, especially if the material could be paired with a high capacity anode material such as silicon (Si). The resulting full-cell was proposed to truly enable the electric vehicle (EV), driving down battery costs to less than $200/kWh while supplying double the drive range of state-of-the-art Li-ion technology. The material, formulated as xLi2MnO3Ÿ(1-x)LiMO2 or Li[LixM1-x]O2 (M = Ni, Mn, Co), is known as the lithium-manganese-rich (LMR) oxide. The beauty of the LMR material lies in the activation process undergone at >4.4 V vs. Li/Li+ during initial charging, resulting in an unprecedentedly high operating voltage and capacities of ~260 mAh g-1.2-8 Despite the potential for massive technological impact, worldwide research has struggled to enable the LMR material. Early work impressively laid the foundation for widespread efforts targeting this material and its signature drawback: the gradual lowering of cell operating voltage over cycling life as the originally layered crystal structure transforms to a spinel phase, accompanied by oxygen evolution during activation of the Li2MnO3 component and transition metal dissolution. In this work, we have focused our efforts on the electrode-electrolyte interactions known to accelerate phase change in the LMR system. Leveraging the understandings of LMR interfacial behavior built by decades of research, we employ a unique electrolyte composition to form a cathode-electrolyte interface (CEI) that allows for the improved long-term voltage stability of the LMR cathode. Our novel CEI is formed in situ through the oxidative decomposition of a room temperature ionic liquid (RTIL) electrolyte doped with a sacrificial fluorinated salt additive. For the first time, we demonstrate an LMR system capable of 1000 high capacity cycles with minimal voltage decay, shedding light on the importance of the LMR CEI and elucidating the complex interplay between the electrolyte and the atomic scale transformations of an unstable crystal lattice. In this talk, these results will be presented in more detail. D. Molina Piper, D. et al. Nat. Commun. 2015, 6, 6230. H. Yu, H. Zhou, J. Phys. Chem. Lett. 2013, 4, 1268. M.M. Thackeray, S.-H Kang, C.S. Johnson, J.T. Vaughey, R. Benedek, S.A. Hackney, J. Mater. Chem. 2007, 17, 3112. G.G. Amatucci, N. Pereira, T. Zheng, J.M. Tarascon, J. Electrochem. Soc. 2001, 148, A171. S.H. Kang, K. Amine, J. Power Sources 2005, 146, 654. M.H. Roussow, M.M. Thackeray, Mater. Res. Bull. 1991, 26, 463. P. Kalyani, S. Chitra, T. Mohan, S. Gopukumar, J. Power Sources 1999, 80, 103. J. Croy, J.S. Park, F. Dogan, C.S. Johnson, B. Key, M. Balasubramanian, Chem. Mater. 2014, 26, 7091.

This presentation reports Si alloy anode materials developed for commercial application for lithium ion batteries(LIBs). This Si alloy material consists of amorphous Si embedded metal-silicide anode materials. It’s synthesized by using mechanical milling. Our alloy have attained a high capacity(energy), high initial efficiency, excellent power property, high coulombic efficiency during cycling. However, sudden failure problem have happened with less FEC contained electrolyte sometimes before 200 or 300 cycles. In an attempt to overcome this major issue, we prepared amorphous C-coated Si alloy, and optimized C-coating process conditions like temperature, carbon contents. As a result, we could improve sudden failure problem with our new amorphous C-coated Si alloy. This new Si alloy’s performance suggests a promising approach to commercial Si anode materials with high capacity.

It has been known that LiBH4 has a hexagonal crystal structure with a high ionic conductivity (~ 10-3 S/cm) above ~ 110 ℃, although it undergoes a reversible phase transformation to an orthorhombic crystal structure with a low ionic conductivity (~ 10-8 S/cm) below the phase transition temperature. So, many researchers attempted to extend the stability region of the high temperature phase up to room temperature by making a solid solution of LiBH4 and lithium halides. Another route to increase the ionic conductivity of LiBH4 is nanoconfinement. The confinement of LiBH4 in the mesoporous scaffolds amorphizes the structure raising the ionic conductivity as high as ~ 10-4 S/cm even at room temperature. However, it is still unclear which mechanism, i.e. nanoconfinement or generation of interface between LiBH4 and SiO2, governs the ionic conductivity enhancement of infiltrated LiBH4. We therefore systematically investigate the ionic conductivity of LiBH4 and a mesoporous silica (here MCM-41) composite system. In order to separate the effect coming from nanoconfinement and interface, as-purchased MCM-41 was hand-mixed with LiBH4 in one case while in the other case mesopores of MCM-41 was intentionally destroyed by high-energy ball-milling. Interestingly, ionic conductivity of ball milled LiBH4 – MCM-41 mixture turned out to be ~ 10-5 S/cm, which is smaller than that of LiBH4 infiltrated into MCM-41 but it is 1000 times higher than that of pure LiBH4. The result highlights the importance of interface effect and indicates that significant enhancement in ionic conductivity can be achieved through interface engineering. To further exploit the interface effect, volume fraction of LiBH4 was systematically varied, and other kinds of compounds were tested. We believe that such approach can be useful for designing a fast ionic conductor for lithium ion battery.

On the advent of flexible devices, developing thin and flexible lithium-ion batteries (FLB) becomes a requisite for full flexible electronic application. Here, we contrived a co-planar type thin and flexible Lithium ion battery by using the design concept of interdigitated electrodes. Whereas a conventional LIB has its components in layer by layer structures, the co-planar type lithium ion battery has the interdigitated structure of positive and negative electrodes on the same plane without a separator, which possibly leads to a thinner battery thickness and stress relieved electrode structure. Unlike previous co-planar type microbatteries, we fabricated pouch cell type batteries with large scale interdigitated electrode structures (~ mm dimension scale) using conventional electrode materials. Our electrochemical tests showed the energy density per cathode area of ~ 1.4 mAh/cm2 and the specific capacity of cathode of 93.61 mAh/g after the cycle test up to 300, which successfully demonstrated the feasibility of a co-planar design pouch cell LIB with the interdigitated electrodes. Furthermore, our mechanical bending test results showed that the co-planar-type battery is mechanically stable during 4000 bending cycles with a bending radius of 1/8 inch.

Resistive switching memory (ReRAM) or Memristor attracted considerable attention due to its technological potential for non-volatile memory and various applications. However, the mechanism is still not resolved clearly because of its difficulties of identifying a conducting channel particularly at oxide systems. Objective of this paper is elucidation of resistive switching mechanism by identifying and analyzing behavior of filaments in-situ in SrTiO3 (STO) and NiO/TiO2 oxides systems. ReRAM can be classified according to different criteria; it can be categorized into unipolar and bipolar systems according to current-voltage (I-V) characteristics, or Electrochemical metallization (ECM), Valence change memory (VCM), and Thermochemical memory (TCM) in terms of different aspects in participation of electrodes in operation. Most of the models that have been presented to explain resistive switching phenomena are based on the formation of filaments, no matter which category their system belongs to. Thus, in order to unravel the mechanism of resistive switching, identifying structure of the filament has its great significance. It has been readily observed in case of the ECM because the filaments, injected metal ion from electrode, are distinguished from electrolyte or insulator. On the contrary, filaments of VCM and TCM have yet to be understood thoroughly. In this paper, our focus will be on the system that could be classified into VCM/TCM. Though grain boundary, defect percolation were suggested as promising candidates of filament at these systems, they have not been clearly verified yet due to their unknown structure, limited size of nanometer scale, and geometry covered by matrix. As the structure and behavior of filament is still controversial, substantial amount of papers reported to unveil the mechanism of resistive switching employed many hypotheses. Here, we identified and analyzed the filament structure at oxide resistive switching system of Pt/SrTiO3/Pt and Pt/NiO/TiO2/Pt, employing in-situ scanning tunneling microscope (STM) / TEM holder. STM tip was in contact with oxide thin film in the TEM and scanned over the region of interest to probe filaments. The filaments could have been detected because of their high conductivity. Consequently, new conducting crystal structure, 2nd phase, is observed in the STO, NiO/TiO2 thin film. Similar as we reported before that 2nd phases of metallic crystals, Magneli TinO2n-1 (n>=4), are generated in the TiO2 thin film as conducting channels. After probing filaments, high-resolution (HR) images and electron-energy loss spectroscopy (EELS) were acquired at corresponding area for determining its crystal and electronic structure respectively. HR images were further analyzed to investigate orientation relationship between the filaments and matrix. EEL spectrum were compared with a simulation data obtained from first principle calculation using Vienna Ab initio simulation package. Furthermore, the sample was turned ‘on’ and ‘off’ repeatedly in-situ and behavior of filament is tracked. The resistance state of the sample was correlated to the structure transformation of filaments. SrTiO3 thin film of 60 nm was deposited by pulsed laser deposition process under oxygen atmosphere and NiO/TiO2 thin film of 50nm was deposited by atomic layer deposition. Platinum pad was exploited for both top and bottom electrodes. Cross-section TEM sample was prepared by focused ion beam. Gatan image filter equipped TEM, F20, was used for in-situ STM/TEM, HR images and EELS.

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The effects of grain size and pattern geometry on the etching rate were investigated by using our invented pattern, and each pattern has a same height of electrodeposits regardless of pattern size after electroplating. It was found out that the logarithmic value of the etching rate is inversely linear with the pattern width at self-annealed specimen. In other words, as the pattern width decreases, the etching rate increases exponentially. Such tendency of the etching rate is owing to the result that the interfacial energies of pattern surface and grain boundary per unit volume increase by the decrease of pattern width. In contrast, the as-deposited sample shows a flat etching rate for pattern sizes. In addition, at the narrow patterns with a pattern width of below 220 nm, the etching rate in the nanocrystalline structure of the as-deposited sample is lower than in the grain grown structure of the self-annealed sample. It can be surmised that the stresses caused by interfacial energies may be relaxed by the nanocrystalline structure in the as-deposited sample.

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We studied the Ni-mediated crystallization of amorphous silicon (a-Si) as a function of its thickness. It was found that the orientation of the poly-Si changed from [110] to [001] when its thickness reduced down to 16 nm.This was confirmed by the analysis of electron backscattered diffraction pattern. The growth of (100)-oriented poly-Si is due to the predominant formation of [001] NiSi 2 nuclei in a thin a-Si network because of its smaller crystalline size compared to that of [110] nuclei.