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Li metal thickness has been considered a key factor in determining the electrochemical performance of Li metal anodes. The use of thin Li metal anodes is a prerequisite for increasing the energy density of Li secondary batteries intended for emerging large-scale electrical applications, such as electric vehicles and energy storage systems. To utilize thin (20 μm thick) Li metal anodes in Li metal secondary batteries, we investigated the synergistic effect of a functional additive (Li nitrate, LiNO3) and a dual-salt electrolyte (DSE) system composed of Li bis(fluorosulfonyl)imide (LiTFSI) and Li bis(oxalate)borate (LiBOB). By controlling the amount of LiNO3 in DSE, we found that DSE containing 0.05 M LiNO3 (DSE-0.05 M LiNO3) significantly improved the electrochemical performance of Li metal anodes. DSE-0.05 M LiNO3 increased the cycling performance by 146.3% [under the conditions of a 1C rate (2.0 mA cm-2), DSE alone maintained 80% of the initial discharge capacity up to the 205th cycle, whereas DSE-0.05 M LiNO3 maintained 80% up to the 300th cycle] and increased the rate capability by 128.2% compared with DSE alone [the rate capability of DSE-0.05 M LiNO3 = 50.4 mAh g-1, and DSE = 39.3 mAh g-1 under 7C rate conditions (14.0 mA cm-2)]. After analyzing the Li metal surface using scanning electron microscopy and X-ray photoelectron spectroscopy, we were able to infer that the stabilized solid electrolyte interphase layer formed by the combination of LiNO3 and the dual salt resulted in a uniform Li deposition during repeated Li plating/stripping processes.

Here, we present a quantitative method to measure the concentration and diffusivity of Li ion in a solid-state electrolyte with nanoscale depth resolution. We designed a standard sample with differ...

In all-solid-state batteries, the electrode has been generally fabricated as a composite of active material and solid electrolyte to imitate the electrode of lithium-ion batteries employing liquid ...

Here, a multimodal scanning probe microscopy study of a composite anode with a dispersed lithium silicon titanium phosphate (LSTP) lithium ion conductor for all-solid-state batteries is presented. ...

All‐solid‐state batteries are promising energy storage devices in which high‐energy‐density and superior safety can be obtained by efficient cell design and the use of nonflammable solid electrolytes, respectively. This paper presents a systematic study of experimental factors that affect the electrochemical performance of all‐solid‐state batteries. The morphological changes in composite electrodes fabricated using different mixing speeds are carefully observed, and the corresponding electrochemical performances are evaluated in symmetric cell and half‐cell configurations. We also investigate the effect of the composite electrode thickness at different charge/discharge rates for the realization of all‐solid‐state batteries with high‐energy‐density. The results of this investigation confirm a consistent relationship between the cell capacity and the ionic resistance within the composite electrodes. Finally, a concentration‐gradient composite electrode design is presented for enhanced power density in thick composite electrodes; it provides a promising route to improving the cell performance simply by composite electrode design.

The future of next-generation rechargeable batteries, such as lithium metal, lithium–sulfur, and lithium–oxygen batteries, hinges on the utilization of metallic lithium as the anode. However, the p...

The key challenge in all-solid-state batteries is to construct well-developed ionic and electric conductive channels within an all-solid-state electrode, with an extensive contact area between electrode components. Hence, a new design methodology is proposed for all-solid-state electrodes utilizing a 3D geometry interpretation tool and electrochemical simulator. Firstly, the 3D structures of all-solid-state electrodes are generated using the voxel array formation. Secondly, with these structures, not only physical properties such as the specific contact area of the active materials, but also conductivity values can be identified. Subsequently, the main parameters derived from the 3D structures are utilized to build an electrochemical model to predict the cell performance. This three-step process will provide key insights on how 3D structures of all-solid-state electrodes must be constructed by predicting their preliminary physical and electrochemical properties with the help of computational simulations.

Lithium metal is considered one of the most promising anode materials for realizing high volumetric and gravimetric energy density, owing to the high specific capacity (∼3860 mAh g−1) and the low electrochemical potential of lithium (−3.04 V vs. the standard hydrogen electrode). However, undesirable dendritic lithium growth and corresponding instability of the solid electrolyte interphase prevent safe and long-term use of lithium metal anodes. This paper presents a simple electrolyte approach to enhance the performance of lithium metal batteries by tuning the dielectric constant of the liquid electrolyte. Electrolyte formulations are designed by changing the concentration of ethylene carbonate to have various dielectric constants. This study confirms that high ethylene carbonate content in a liquid electrolyte enhances the cycling performance of lithium metal batteries because the electric field intensity applied to the electrolyte is reduced in relation to the polarization of the electrolyte and thus allows smooth lithium plating and formation of a stable solid electrolyte interphase. We believe that this approach provides an important concept for electrolyte system design suitable to lithium metal batteries.

A method of microalgae-templated spray drying to develop hierarchical porous Fe3O4/C composite microspheres as anode materials for Li-ion batteries was developed. During the spray-drying process, individual microalgae serve as building blocks of raspberry-like hollow microspheres via self-assembly. In the present study, microalgae-derived carbon matrices, naturally doped heteroatoms, and hierarchical porous structural features synergistically contributed to the high electrochemical performance of the Fe3O4/C composite microspheres, enabling a discharge capacity of 1375 mA&middot, h&middot, g&minus, 1 after 700 cycles at a current density of 1 A/g. Notably, the microalgal frameworks of the Fe3O4/C composite microspheres were maintained over the course of charge/discharge cycling, thus demonstrating the structural stability of the composite microspheres against pulverization. In contrast, the sample fabricated without microalgal templating showed significant capacity drops (up to ~40% of initial capacity) during the early cycles. Clearly, templating of microalgae endows anode materials with superior cycling stability.

Summary In contrast to enormous progresses in electrode active materials, little attention has been paid to electrode sheets despite their crucial influence on practical battery performances. Here, as a facile strategy to address this issue, we demonstrate nanofibrous conductive electrode binders based on deoxyribonucleic acid (DNA)-wrapped single-walled carbon nanotubes (SWCNT) (denoted as DNA@SWCNT). DNA@SWCNT binder allows the removal of conventional polymeric binders and carbon powder additives in electrodes. As a proof of concept, high-capacity overlithiated layered oxide (OLO) is chosen as a model electrode active material. Driven by nanofibrous structure and DNA-mediated chemical functionalities, the DNA@SWCNT binder enables improvements in the redox reaction kinetics, adhesion with metallic foil current collectors, and chelation of heavy metal ions dissolved from OLO. The resulting OLO cathode exhibits a fast charging capability (relative capacity ratio after 15 min [versus 10 h] of charging = 83%), long cyclability (capacity retention = 98% after 700 cycles), and thermal stability., Graphical Abstract, Highlights • A multifunctional binder based on DNA-wrapped SWCNT is demonstrated • DNA@SWCNT binder shows improved adhesion with metallic foil current collectors • DNA@SWCNT binder enables chelation of heavy metal ions dissolved from cathode materials • DNA@SWCNT binder-containing cathode exhibits fast-charging capability, Nanotechnology; Nanomaterials; Energy Materials

The electrochemical performance of layered LiNi1-xCox/2Mnx/2O2 cathode materials (x = 2/3, 0.4, 0.2; so-called NCM333, NCM622, NCM811) in 1.0 M LiPF6-dissolved conventional carbonate-based electrolyte during formation at a 0.1 C-rate and consequent cycling at a 1.0 C-rate is measured and considered together with the results of morphology observation, impedance spectroscopy, and surface analysis. X-ray photoelectron spectroscopy (XPS) is carried out on the surface of the cathode materials before and after formation and cycling to investigate the effects of solid electrolyte interphase (SEI) formation on the electrochemical performance. As the Ni content increases, the initial specific capacity increases but the capacity retention ratio decreases. High-rate cycling overrides the SEI formation on the NCM surfaces, but NCM622 suffers great changes in the SEI components with a thick layer resulting in large interfacial resistance. It is also proved that NCM811 shows significant dissolution and accumulation of Ni species on the surface, contributing structural degradation and leading to fast capacity fading.

Two micro-patterns of different sizes (50 and 80 μm) are designed to have equivalent capacities of 1.06 and 2.44 mAh cm−2 by building a computational battery model. After preparing two stamps each possessing a micro-pattern design, the corresponding pattern is properly imprinted on the surface of 100 μm lithium metal, which is confirmed by scanning electron microscopy. When both micro-patterned lithium metals are electrochemically reduced and oxidized up to 1 mAh cm−2 in Li/Li symmetric cells at 1 or 2 mA cm−2, the 80 μm-patterned lithium shows a more stabilized lower overpotential during long-term cycling than the 50 μm-patterned and bare lithium, probably due to the lithium anchoring effect and a larger empty volume in the patterns. Additionally, an overflow of lithium deposits is easily observed in the 50 μm-patterned lithium metal, while the 80 μm-patterned lithium metal holds most of the lithium deposits within the patterns. When both micro-patterned lithium metals are assembled to full cells with a LiNi0·6Co0·2Mn0·2O2 cathode of 2 mAh cm−2, the 80 μm-patterned lithium metal shows much better electrochemical performances with stable plating/stripping behavior within the patterns.

All-solid-state lithium-ion batteries (ASLBs) are receiving considerable attention due to their safety superiority and high energy density (achieved by bipolar configuration). Inorganic solid electrolytes are explored as a key-enabling material of the ASLBs. However, their critical challenges, including grain boundary resistance, interfacial instability with electrode materials and complicated processability, remain yet unresolved. Here, we demonstrate a new class of gel electrolyte with reversible thixotropic transformation and abuse tolerance as an effective and scalable approach to address the aforementioned longstanding issues. The gel electrolyte consists of (fluoropolymer/cellulose derivative) matrix and liquid electrolyte. The reversible thixotropic transformation is realized via sol-gel transition based on Coulombic interaction of the polymer matrix with liquid electrolyte. This unusual rheological feature allows the gel electrolyte to be printed in various forms. In addition, the gel electrolyte shows low crystallinity, thus playing a viable role in delivering high ionic conductivity. Based on understanding of rheological/electrochemical characteristics of the gel electrolyte, we fabricate a form factor-free pouch-type cell assembled with the gel electrolyte using sequential screen-printing process. The resultant cell shows exceptional safety upon exposure to various harsh abuse conditions, along with decent electrochemical performance.

A facile method for preparing mesoporous perforated Co3O4 nanoparticles with hollow channels and a thin carbon layer was newly designed and achieved with sacrificial carbon nanotube (CNT) templates. The threaded Co3O4 nanoparticles on the CNTs were fabricated through a hybridization process, and a subsequent calcination process produced mesoporous perforated Co3O4 nanoparticles. With a finely tuned calcination, CNTs were sacrificed to generate hollow channels in the Co3O4 nanoparticles and to provide a carbon source for the formation of a few nm-thick carbon layer on the surface of the Co3O4 nanoparticles simultaneously. The prepared mesoporous perforated Co3O4 nanoparticles with a robust electronic conductive layer enabled not only an enhanced electrochemical reactivity from the greatly increased contact area between the electrolyte and electrode but also a high electronic conductivity of the overall electrode so that excellent electrochemical performances (1115.1 mA h g−1 after 100 cycles; 595.9 mA h g−1 @ 5 C rate) were successfully achieved in the anode application of a lithium-ion battery.

High-voltage operation of lithium-ion batteries (LIBs) is a facile approach to obtaining high specific energy density, especially for LiNi0·5Mn0·3Co0·2O2 (NMC532) cathodes currently used in mid- and large-sized energy storage devices. However, high-voltage charging (>4.3 V) is accompanied by a rapid capacity fade over long cycles due to severe continuous electrolyte decomposition and instability at the cathode surface. In this study, the sulfite-based compound, [4,4′-bi(1,3,2-dioxathiolane)] 2,2′-dioxide (BDTD) is introduced as a novel electrolyte additive to enhance electrochemical performances of alumina-coated NMC532 cathodes cycled in the voltage range of 3.0–4.6 V. X-ray photoelectron spectroscopy (XPS) and AC impedance of cells reveal that BDTD preferentially oxidizes prior to the electrolyte solvents and forms stable film layers on to the cathode surface, preventing increased impedance caused by repeated electrolyte solvent decomposition in high-voltage operation. The cycling performance of the Li/NMC532 half-cell using an electrolyte of 1.0 M LiPF6 in ethylene carbonate/ethyl methyl carbonate (3/7, in volume) can be improved by adding a small amount of BDTD into the electrolyte. BDTD enables the usage of sulfite-type additives for cathodes in high-voltage operation.

One of the challenges in developing Lithium anodes for Lithium ion batteries (LIB) is controlling the formation of Li dendrites during cycling of the battery. Nanostructuring and nanopatterning of electrodes shows a promising way to suppress the growth of Li dendrites. However, in order to control this behavior, a fundamental understanding of the effect of nanopatterning on the electro-mechanical properties of Li metal is necessary. In this paper, we have investigated the mechanical and wear properties of Li metal using Atomic Force Microscopy (AFM) in an airtight cell. By using different load regimes, we determined the mechanical properties of Li metal. We show that as a result of nanopatterning, Li metal surface underwent work hardening due to residual compressive stress. The presence of such stresses can help to improve cycle lifetime of LIBs with Li anodes and obtain very high energy densities. Keywords: Nanopatterning, mechanical properties, Li anode, Lithium ion batteries

A controlled release system (CRS) is a successful treatment method in biomedical engineering that can deliver the therapeutic dosage of the drug over an extended period of time, with a single dose. Herein, we demonstrated an unusual approach of combining a CRS with an energy storage device to improve the electrochemical stability of lithium secondary battery with the therapeutic dosage. We have designed a sophisticated release system comprised of a model active substance (vinylene carbonate (VC)) and a naturally abundant one-dimensional inorganic nanocarrier (halloysite nanotube (HNT)). Its effectiveness in the energy storage device was verified using the lithium battery. The establishment of in vitro release measurement over time using gas chromatography in this study enabled the precise estimation of the release pattern. The VC encapsulated in the HNTs improved cycling stability of the LiNi0.6Mn0.2Co0.2O2/Li battery system than those with the simple VC introduction and the simple mixture of VC and HNTs by enhancing the interfacial stability of the battery electrodes with the progression of the charge-discharge cycles. The VC loaded HNT not only provides continuous release of VC for repairing SEI but also builds the robust organic-inorganic SEI layer (HNT incorporated poly (VC)). The proof-of-concept of the proposed CRS is also investigated using another active substance (tris (trimethylsilyl) borate), where the compatibility with the battery is verified, and the cell performance is notably improved. This study proposes important insights regarding the use of the CRS in energy storage devices.

All-solid-state lithium-ion batteries (ASLBs) are regarded as the next generation of energy storage devices owing to their excellent safety. However, the performance of ASLBs has yet to reach that of currently commercialized liquid electrolyte-based lithium-ion batteries due to numerous problems including the inferior ionic conductivities of solid electrolytes (SEs) and poor solid-solid interfacial contact between the SE and active material particles. Herein, dimensional control of SE particles using liquid phase synthesis is demonstrated and its favorable impact on cell performance is investigated. Argyrodite Li6PS5Cl SE with high ionic conductivity of 1.54 mS cm-1 and distinct 2D morphology was synthesized using 2D structured reduced graphene oxide as the template. The SE particles with high aspect ratio improves the long-range connectivity of the SE within the composite electrode and provides a well-connected ionic transport pathway for charge-discharge. The electrochemical impedance spectroscopy analysis of the composite electrode using electron blocking cell configuration revealed threefold enhancement of the effective ionic transport within the composite. As a result, superior rate performance was demonstrated with 2D SE composite electrodes at high C rates.

Transparent conducting electrodes (TCEs) are essential components in various optoelectronic devices. Nanostructured metallic thin film is one of the promising candidates to complement current metal oxide films, such as ITO, where high cost rare earth elements have been a longstanding issue. Herein, we present that multiscale porous metal nanomesh thin films prepared by bimodal self-assembly of block copolymer (BCP)/homopolymer blends may offer a new opportunity for TCE. This hierarchical concurrent self-assembly consists of macrophase separation between BCP and homopolymer as well as microphase separation of BCP, and thus provides a straightforward spontaneous production of a highly porous multiscale pattern over an arbitrary large area. Employing a conventional pattern transfer process, we successfully demonstrated a multiscale highly porous metallic thin film with reasonable optical transparency, electro-conductance, and large-area uniformity, taking advantage of low loss light penetration through microscale pores and significant suppression of light reflection at the nanoporous structures. This well-defined controllable bimodal self-assembly can offer valuable opportunities for many different applications, including optoelectronics, energy harvesting, and membranes.

The combination of high specific-capacity lithium (Li) metal anode and high cut-off voltage in Li secondary batteries provides an innovative method to realize high energy-density rechargeable batteries that satisfy the needs of future applications. However, an upgrade of both the cathode and anode is vital to establish high-voltage lithium metal batteries (LMB) concepts. In this study, we fabricated an electrolyte additive, [4, 4′-bi(1,3,2-dioxathiolane)] 2,2′-dioxide (BDTD), based on a novel sulfite-type additive and applied in LMB. Suppression of the Li dendrite growth on the Li metal anode was ensured by homogeneous Li plating in Li/Li symmetric cells. Scanning electron microscopy images demonstrated anode stabilization due to the introduction of the BDTD additive. In addition, X-ray photoelectron spectroscopy results confirmed the stabilization of the LiNi0.6Mn0.2Co0.2O2 cathode by protective cathode-electrolyte interphase made from the BDTD additive. This single additive introduced in the electrolyte enhanced both electrodes synergistically, and thus it resulted in an extended cycle life with high capacity retention in the high-voltage operation (4.6 V). We believe that this study will open new avenues for fabricating batteries with high-energy-density from high-voltage LMBs via this dual-function additive.

We prepared and optimized the ionically conducting perovskite-type Li 0.33 La 0.56 TiO 3 by an adipic acid-assisted sol-gel process. A high ionic conductivity of 0.131 mS cm −1 was obtained at an ambient temperature by adjusting the synthesis temperature, holding time, and cooling process. A dramatic improvement in the Li 0.33 La 0.56 TiO 3 conductivity was noted in each step. Interestingly, a tetragonal-to-cubic structural transition was evident during the quenching process unlike in the conventional slow cooling process. An increase in the bottleneck site volume was observed that facilitated Li + ion migration for enhanced conductivity.

Bulk-type all-solid-state lithium-ion batteries (ASLBs) for large-scale energy-storage applications have emerged as a promising alternative to conventional lithium-ion batteries (LIBs) owing to their superior safety. However, the electrochemical performance of bulk-type ASLBs is critically limited by the low ionic conductivity of solid electrolytes (SEs) and poor ionic contact between the active materials and SEs. Herein, highly conductive (0.14 mS cm-1 ) and dry-air-stable SEs (Li4 SnS4 ) are reported, which are prepared using a scalable aqueous-solution process. An active material (LiCoO2 ) coated by solidified Li4 SnS4 from aqueous solutions results in a significant improvement in the electrochemical performance of ASLBs. Side-effects of the exposure of LiCoO2 to aqueous solutions are minimized by using predissolved Li4 SnS4 solution.

Functional separators, which have additional functions apart from the ionic conduction and electronic insulation of conventional separators, are highly in demand to realize the development of advanced lithium ion secondary batteries with high safety, high power density, and so on. Their fabrication is simply performed by additional deposition of diverse functional materials on conventional separators. However, the hydrophobic wetting nature of conventional separators induces the polarity-dependent wetting feature of slurries. Thus, an eco-friendly coating process of water-based slurry that is highly polar is hard to realize, which restricts the use of various functional materials dispersible in the polar solvent. This paper presents a surface modification of conventional separators that uses a solution-based coating of graphene oxide with a hydrophilic group. The simple method enables the large-scale tuning of surface wetting properties by altering the morphology and the surface polarity of conventional separators, without significant degradation of lithium ion transport. On the surface modified separator, superior wetting properties are realized and a functional separator, applicable to lithium metal secondary batteries, is demonstrated as an example. We believe that this simple surface modification using graphene oxide contributes to successful fabrication of various functional separators that are suitable for advanced secondary batteries.

The surface area of the lithium metal electrode must be considered when attempting to suppress dendritic growth of lithium metal, as surface area can lower the effective current density. For this reason, lithium metal powder (LiMP) has attracted much attention for use in electrodes because of its higher surface area. However, repeated cycling, even in aging time, leads to delamination of lithium particles from flat metal current collectors and results excess dead lithium particles, even in LiMP electrodes. Herein, this problem is addressed by coating submicron-thickness carbon interlayers on copper current collectors for LiMP electrodes. This thin carbon layer plays important roles in both maintaining the interfacial contact between Cu foil and LiMP particles and lowering overpotential in Li/Li symmetric cells, which leads to improve electrochemical performance in thin LiMP (40 μm) based cell. These enhancements are related to the enlarged surface area, as confirmed by higher adhesion of the electrode after precycling. Furthermore, the carbon materials are also believed to contribute to seeding for efficient lithium nucleation. Thus, thin carbon layers on current collectors can provide simple but powerful enhancements to the electrochemical performance of high-energy-density LMSBs.

The use of lithium metal in secondary batteries has been impeded by its tendency to form dendrites: branching conductive structures of metal that can lead to capacity loss and, ultimately, internal shorts in the battery. Patterned electrodes, in addition to artificially increasing the current density of cells by increasing the surface area available for reaction, also generate a nonuniform electric field in the vicinity of the electrode surface. This nonuniform electric field, though rapidly screened by the electrolyte, can promote inhomogeneous deposition and Solid Electrolyte Interphase formation. As the consequence of these effects is not theoretically apparent since Solid Electrolyte Interphase volume and conductivity changes can, in principle, offset variations in local current density, we have performed experiments to examine the deposition of Li on nonuniform electrode surfaces using Atomic Force Microscopy. We measure the local variations in topography, SEI thickness, and composition, and discuss their implications for the formation of dendrites in Li metal.

© 2016 ETRI Journal, Volume 38, Number 2, April 2016 http://dx.doi.org/10.4218/etrij.16.2515.0018 Di(1-aminopyrene)quinone (DAQ) as a quinonecontaining conducting additive is synthesized from a solution reaction of 1-aminopyrene and hydroquinone. To utilize the conductive property of DAQ and its compatibility with activated carbon, a composite electrode for a supercapacitor is also prepared by blending activated carbon and DAQ (3:1 w/w), and its supercapacitive properties are characterized based on the cyclic voltammetry and galvanostatic charge/discharge. As a result, the composite electrode adopting DAQ exhibits superior electrochemical properties, such as a higher specific capacitance of up to 160 F·g at 100 mV·s, an excellent high-rate capability of up to 1,000 mV·s, and a higher cycling stability with a capacitance retention ratio of 82% for the 1,000th cycle.

Layered electrodes of electrodeposited RuO 2 (eRuO 2 ) and polyaniline (ePAn) are prepared on a platinum substrate to yield ePAn-on-eRuO 2 and eRuO 2 -on-ePAn electrodes and their supercapacitive properties are investigated. The eRuO 2 electrode forms a compact stratified structure with nearly flat surfaces by electrodeposition from a RuCl 3 ·3H 2 O-based solution, whereas the ePAn electrode forms densely connected particles or particle aggregates by the electrodeposition from aniline solution. In the scan rate range of 20–1000 mV s −1 , specific capacitance (810–575 F g −1 ) of ePAn-on-eRuO 2 electrode is superior by the higher probability to occur redox reaction and proton diffusion due to particulate surface and inner pores of the upper layer (ePAn), respectively. In contrast, the eRuO 2 -on-ePAn electrode loses the specific capacity (680–550 F g −1 ) but achieves higher capacity retention ratio (81%) by flat compact surface of the upper layer (eRuO 2 ).

We report the fabrication of a carbon-based high energy density Li-ion hybrid electrochemical capacitor (Li-HEC) from low cost and eco-friendly materials. High surface area (2448±20 m(2) g(-1) ) activated carbon (AC) is derived from the environmentally threatening plant, Prosopis juliflora, and used as the positive electrode in a Li-HEC assembly. Natural graphite is employed as negative electrode and electrochemically pre-lithiated prior to the Li-HEC fabrication. The Li-HEC delivers a specific energy of 162.3 Wh kg(-1) and exhibits excellent cyclability (i.e., ∼79 % of initial capacity is retained after 7000 cycles). The superior electrochemical performance of Li-HEC benefits from the tube-like unique structural features of the AC. Also, the presence of a graphitic nanocarbon network improves the ion transport, and the formed micro- and meso-porous network acts as reservoir for the accommodation of charge carriers.

Solid oxides are attractive electrolyte materials for all-solid-state lithium batteries (ASSLBs) owing to their high stability and pure Li-ion conductivity. Nevertheless, the electrochemical performance of ASSLBs employing solid oxide-based electrolytes cannot compete with ASSLBs with sulfide or polymeric electrolytes due to poor interfacial contact and high boundary resistance between the active materials and solid oxide electrolytes. To overcome this hurdle, elaborate microstructural analysis of the interface of the active material/solid oxide electrolyte in ASSLBs is essentially required since the interfacial contact area dominantly acts as the ion pathway and the electrochemical reaction site in the electrode. Although recent attempts on interfacial structure analysis of ASSLBs have provided simple 2D or semi-3D microstructural features, the results have not yielded deep insights. Herein, we investigated the interfacial defects in an all-solid-state electrode with a solid oxide electrolyte via a 3D digital twin technology combining 3D structural quantification and physico-electrochemical simulations to unravel the intrinsic limitations of solid oxide electrolytes. The in-depth results can be used to design materials and optimize electrode design parameters for ASSLBs.

The high-rate half-cell performance of LiNi0.3Co0.3Mn0.3O2 (NCM333), LiNi0.6Co0.2Mn0.2O2 (NCM622), and LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode materials is investigated with the base electrolyte of LiPF6/ethylene carbonate (EC):ethylmethyl carbonate (EMC) and the additives of vinylene carbonate (VC) and 1,3-propane sultone (PS). The effects of these additives on the cathode surfaces are particularly examined in terms of the reduction products of the electrolyte components and the formation of solid electrolyte interphase (SEI) on cathode surfaces. The cathode SEI appears less after formation for all NCM materials, but it accumulates with repeated charging/discharging at a high rate. Of these, the addition of VC + PS to the base electrolyte sufficiently provides stable cathode SEI with suppressed thickness under cycling at a high rate by inhibiting the further decomposition of reduction products. The synergy of VC + PS may be originated by the combination of vinyl and sulfone functional groups to provide passivation film with cross-linked protective networks on Ni-rich NCM cathode materials. Thus, superior cycle performance is achieved, especially for NCM811.

Effects of soluble polyimide (PI) binders on large-sized Li anodes (width = 21.5 cm; thickness = 40 μm) prepared using Li-metal powder (LiMP) have been investigated. PI binders form a uniform protective layer on exposed Li-powder-coated surfaces, thereby resulting in formation of scaffold-structured LiMP-based anodes. Uniform PI surface films favor realization of Li plating on Li-metal surfaces by forming a smooth surface structure, and the three-dimensional insulating PI matrix functions as a buffer layer that absorbs volume change. Moreover, PI binders facilitate enhanced cohesion between LiMP particles. The above-described triple action of PI binders significantly reduces Li dendrites. Consequently, PI-containing LiMP-based metal anodes demonstrate enhanced electrochemical performance compared to both polymeric binders and bare Li-metal foils. Results obtained in this study reveal that LiMP-based anodes containing PI binders exhibit 89% (98.2 mAh g–1) discharge-capacity retention during the 200th cycle, whereas bare Li-metal foil demonstrates sudden degeneration during the 65th cycle. Furthermore, PI containing LiMP-based anodes exhibit improved rate capability compared to other polymeric binders considered in this study.

All-solid-state lithium secondary batteries have never shown both higher energy and power density than them of conventional lithium-ion batteries. Herein, on the basic of well-established percolation theory, we expected what includes a dimension-controlled solid electrolyte in an electrode can improve the electrochemical properties, such as ionic conduction and capacity retention. The behavior of electrodes is systematically demonstrated via computational simulations of virtual electrodes with various dimension-controlled solid electrolytes. In particular, the effective ionic conductivity and the specific contact area are investigated as key parameters that determine cell performance. We confirmed that the dimension-controlled solid electrolyte can improve the electrochemical performance of all-solid-state batteries by enhancing the effective ionic conductivity, which is facilely realized via percolation of the solid electrolyte with an increased dimensional geometry. This simulation prediction suggests a clue to be able to overcome poor performance of present all-solid-state batteries.

To enhance the electrochemical performance, a conventional activated carbon supercapacitor is modified by adopting potassium-polyacrylate (PAAK) electrolyte additive on a glass fiber separator and by fabricating the activated carbon electrode on nickel foam instead of on conventional nickel foil as a current collector. The glass fiber separator plays the role of self-supporting PAAK-KOH hydrogel electrolyte with superior ionic conductivity. Moreover, the adoption of nickel foam strengthens the close contact between the active material and the current collector, reducing the interfacial resistance between electrode and electrolyte. As a result, the combination of glass fiber separator and nickel foam substrate can contribute to a great increase in the specific capacitance, to a value of over 200 F g−1, and to an enhancement of the high-rate capability of activated carbon supercapacitors.

Bulk-type all-solid-state lithium-ion batteries (ASLBs) using sulphide solid electrolytes (SEs) are considered as one of the promising alternative batteries because of their ultimate safety and scalable fabrication. However, they suffer from poor ionic contacts between active materials and SEs. Herein, we report, for the first time, the excellent electrochemical performances of sulphide-SE-based bulk-type ASLBs employing TiS2 nanosheets (TiS2-NSs) prepared by scalable mechanochemical lithiation, followed by exfoliation in water under ultrasonication. The TiS2-NS in all-solid-state cells exhibits an enhancement of reversible capacity which is attributed to the SE region in intimate contact with TiS2-NSs. Importantly, an exceptionally superior rate capability of the TiS2-NS compared to that of bulk TiS2 and even ball-milled TiS2, which is attributed to the ultrathin 2D structure (with short Li-ion diffusion length and intimate contacts between the TiS2-NS and SE) and high electronic conductivity, is highlighted.

Li1+xAlxTi2-x(PO4)3 (LATP) solid electrolytes are prepared by hydrothermal reaction as an effective method to yield moderate ionic conductivity adoptable in actual lithium-ion batteries. Particularly examined in this study are the effects of the synthesis conditions, such as Al dopant concentration (x), hydrothermal reaction time, and calcination and sintering temperatures, on the ionic conductivity of the synthesized LATP. Through repeated synthesis and characterizations of the LATPs by variation of the values of condition variables, the optimum condition for the best LATP with adequate ionic conductivity applicable to actual lithium batteries are determined to be x = 0.3 or 0.4, a hydrothermal reaction time of 12 h, and calcination and sintering temperatures of 600 °C and 900 °C, respectively.

We report the synthesis of two-dimensional (2D) Co3S4 in a nanothickness sheetlike morphology via simple hydrothermal process and its application to electrochemical energy-storage devices. The presence of unique mesopores with a combination of core/shell nanoparticles in the nanosheets showed superior electrochemical performances as a negative electrode for a Li-ion battery (LIB) and an electrocatalyst in Li–O2 battery applications. A high discharge capacity of ∼968 mAh g–1 is noted after 60 cycles with excellent cycling stability when evaluated as an anode for a LIB. On the other hand, the first discharge capacity of ∼5917 mAh g–1 is observed with a high reversibility of 95.72% for the Li–O2 battery point of view. This exceptional electrochemical performance in both applications is mainly attributed to the presence of mesoporous with core/shell 2D nanostructure, which translates more catalytic bifunctional (oxygen reduction reaction/oxygen evolution reaction) active sites for Li–O2 and sustains the volum...

Three kinds of polydimethylsiloxane (PDMS)-based grafted and ungrafted copolymers such as poly[dimethylsiloxane- co -(siloxane- g -acrylate)] (PDMS-A), poly(dimethylsiloxane- co -phenylsiloxane) (PDMS-P), and poly[dimethylsiloxane- co -(siloxane- g -ethylene oxide)] (PDMS-EO) are used as additives to standard liquid electrolyte solutions to enhance the lithium-ion battery performance at low temperatures. Liquid electrolyte solutions with PDMS-based additives are electrochemically stable under 5.0 V and have adequate ionic conductivities of 10 −4 S cm −1 at -20 °C. Particularly, liquid electrolytes with PDMS-P and PDMS-EO exhibit higher ionic conductivities of around 5 × 10 −4 S cm −1 at -20 °C, indicating a specific resisting property against the freezing of the liquid electrolyte components. As a result, the addition of PDMS-based additives to liquid electrolytes improves the capacity retention ratio and rate-capability of lithium-ion batteries at low temperatures.

A facile direct hybridization route to prepare SnO2/graphene nanocomposites for Li-ion battery anode application is demonstrated. Uniform distribution of SnO2 nanoparticles on graphene layers was enabled by a one-step chemical synthetic route. The optimal content ratio of SnO2 and graphene was determined from microscopic observations and electrochemical studies. The nanocomposite anode with SnO2 loading level of around 70 wt.% retained reversible capacity of 643.6 mAh/g after 50 cycles and high discharge capacity of 347.8 mAh/g at a current density of 3000 mA/g, which was superior to that of graphene-only electrodes or nanocomposites with overloaded SnO2 nanoparticles. Taking advantage of nano-sized SnO2 and an electrically conductive and mechanically flexible graphene layer, SnO2/graphene nanocomposites with optimized SnO2 content exhibit excellent electrochemical properties as lithium-ion battery anodes. Our strategy offers a straightforward and high-throughput pathway for creating and directing graphene-based functional hybrids through simple mixing and thermal treatments, and may be used to assemble high-performance Li-ion batteries.

A flexible hybrid anode from graphite and thin film silicon is realized by the concept of a 3D sandwich current collector by the combination of micro-contact printing and RF magnetron sputtering. Flexible lithium-ion batteries with a new hybrid anode demonstrate not only enhanced specific capacity but also improved rate capability compared to that of a conventional graphite anode under bending deformation.

Porous polyethylene (PE) or nonwoven poly(vinylidene fluoride) (PVdF) separator-supported gel polymer electrolytes are realized by thermal polymerization of a precursor solution consisting of poly(ethylene glycol)diacrylate (PEGDA) and an electrolyte solution (1 M LiPF 6 in an equal-volume mixture of ethylene carbonate and dimethyl carbonate). The polymerization conditions are optimized to include a PEGDA content of 3 wt.% in the precursor solution and subsequent heat treatment at 80 °C for 10 min. Even though the gelled PEGDA electrolyte has a lower ionic conductivity than the electrolyte solution, a Li x CoO 2 /graphite full-cell that has a gel electrolyte with optimized PEGDA content on the PVdF separator achieves a battery performance superior to the one with PE. The best battery performances achieved are a high discharge capacity (116 mAh g −1 ), a good high-rate capability (95 mAh g −1 at 5.0 C-rate), and a high capacity retention ratio (90%) after the 100th cycle. This enhancement is due to the incorporation of a polar electrolyte solution that is entrapped by the polar PEGDA matrix within the nonwoven PVdF separator, which is a more suitable host that is able to well absorb and preserve the gel electrolyte.

For use as an anode material in lithium batteries, composites consisting of TiO2 nanotubes (TNTs) and carbon nanotubes (CNTs) are prepared by combining hydrothermal reaction of rutile TiO2 bulk particles, blending with different amounts (0–30 wt.%) of CNTs, ball-milling, and subsequent heat treatment at 300 °C. Crystalline property analysis and morphology observation of the prepared TNT-CNT powders prove that at low CNT content the composites are consisted of dominant phase of aggregated anatase TNTs. The TNT aggregates are relaxed with increased CNT content to form crosslinked networks surrounding the amorphous CNT phases that act as a dispersing matrix. As a result, the TNT-CNT composite anode with CNT (30 wt.%) is superior for application in lithium-ion batteries because it shows a saturated discharge capacity after about 20th cycle, good high-rate capability, and the lowest interfacial resistance of 1.7–2 Ω cm−2. The superior anode properties of TNT-CNT composite with high content of CNT are mainly due to CNT’s functions to enhance electron transfer and to facilitate Li+ diffusion by dispersing the TNT agglomeration.

Hydrous ruthenium oxide (RuO 2 ) is prepared by electrodeposition on a platinum substrate and its supercapacitive properties are characterized adopting acrylic gel polymer electrolytes, such as poly(acrylic acid) (PAA), potassium polyacrylate (PAAK), and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). The electrodeposited hydrous RuO 2 exhibits an amorphous compact stratified morphology with a higher loading (0.15 mg cm −2 ) than that of a previous report, and shows broad redox peaks on both cathodic and anodic scans in the cyclic voltammetry. In particular, the RuO 2 electrode for supercapacitor adopting the PAMPS electrolyte shows the highest specific capacitance of 642 F g −1 at 20 mV s −1 . This is due to the efficient utilization of active RuO 2 species and greater proton accommodation toward the negative oxygen sites of PAMPS's side chain. In addition, it is possible to improve sustainability against high-rate current with the RuO 2 electrode with the PAMPS electrolyte, due to the crosslinks of the gel electrolyte, which support the mechanical strength.

Hydrophobic polyolefin (polyethylene and polypropylene) separators are modified to encompass hydrophilicity on their surfaces through sulfonation, and then coated by polymer hydrogel electrolyte composed of 6 M KOH, potassium polyacrylate (PAAK) (1.5 wt.%), and the ceramic nanoparticles (10 wt.%) of SiO2, TiO2, and Al2O3. The ceramic filler-coated sulfonated polyolefin separators are applied to a supercapacitor with two symmetric activated carbon electrodes. The supercapacitors with the sulfonated polyolefin separators coated with ceramic filler-PAAK hydrogel electrolytes exhibit superior electrochemical performance, especially in the high scan rate region, compared to the case of coating the pure PAAK hydrogel electrolyte without ceramic fillers. In particular, the PAAK hydrogel electrolyte with SiO2 contributes to a higher specific capacitance at a high scan rate due to the strong hydrophilicity originated from both the sulfonated separator surfaces and the SiO2 nanoparticles.

The corrosion property of aluminum by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is investigated in liquid and gel electrolytes consisting of ethylene carbonate/propylene carbonate/ethylmethyl carbonate/diethyl carbonate (20:5:55:20, vol %) with vinylene carbonate (2 wt %) and fluoroethylene carbonate (5 wt %) using conductivity measurement, cyclic voltammetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. All corrosion behaviors are attenuated remarkably by using three gel electrolytes containing 3 wt % of hydrophilic and hydrophobic fumed silica. The addition of silica particles contributes to the increase in the ionic conductivity of the electrolyte, indicating temporarily formed physical crosslinking among the silica particles to produce a gel state. Cyclic voltammetry also gives lower anodic current responses at higher potentials for repeating cycles, confirming further corrosion attenuation or electrochemical stability. In addition, the degree of corrosion attenuation can be affected mainly by the electrolytic constituents, not by the hydrophilicity or hydrophobicity of silica particles.

A new Cu current collector was prepared by introducing a mussel-inspired polydopamine coating onto a Cu foil surface to improve the electrochemical performance of a Si electrode. The polydopamine coating covalently bonded the polymeric binder (with hydroxyl functional groups) via a condensation reaction. The coating improved the adhesion strength between the Si composite electrode and the Cu current collector (245.5 N m−1, 297.5 N m−1, and 353.2 N m−1 for the Si electrodes based on bare Cu, polydopamine-treated Cu without thermal treatment, and polydopamine-treated Cu with thermal treatment, respectively). We demonstrate that the detachment between the Si composite electrode and the current collector plays an important role in determining the electrochemical performance of the Si electrode. The cycle life and rate capability of the Si electrode improved when the polydopamine surface-treated Cu current collector was used (963.9 mAh g−1, 1361.1 mAh g−1, and 1590.0 mAh g−1 for the Si electrodes based on bare Cu, polydopamine-treated Cu without thermal treatment, and polydopamine-treated Cu with thermal treatment, respectively, at C/2 after 500 cycles).

A high-energy-capacity, flexible lithium-ion battery is fabricated using a new nanofibril-structured silicon anode on a flexible current collector. Silicon is known to be the highest capacity anode material. However, its huge volume changes during the lithium insertion and extraction results in pulverization, which is the cause of the rapid capacity fade that occurs as the charge-discharge cycles progress. Nanostructured silicon can overcome this pulverization problem. A flexible current collector with high electric conductivity is prepared by a RF-magnetron sputtering of a thin copper layer (

To use as an anode material of lithium batteries, carbon-coated TiO 2 nanotubes are prepared by hydrothermal reaction of rutile particles, subsequent sol–gel mixing with poly(vinyl pyrrolidone), and heat treatment at 300–500 °C. The carbon-coated TiO 2 nanotubes are also characterized by morphology observation, crystalline property analysis, potentiostatic redox behaviors, and galvanostatic discharge–charge evaluations at low and high rates. When annealed at 300 °C, the amorphous phase of carbon layers which are covered on the TiO 2 nanotubes dominates the anatase TiO 2 nanocrystalline phase. When annealed at 500 °C, the carbon-coated TiO 2 nanotubes exhibit superior cyclic performance and high-rate capability, due to the crystalline phase in the carbon-coated layer formed by annealing at high temperature.