Simultaneous Realization of Multilayer Interphases on a Ni-Rich NCM Cathode and a SiOx Anode by the Combination of Vinylene Carbonate with Lithium Difluoro(oxalato)borate.

Ni-rich NCM and SiOx electrode materials have garnered the most attention for advanced lithium-ion batteries (LIBs); however, severe parasitic reactions occurring at their interfaces are critical bottlenecks in their widespread application. In this study, an effective additive combination (VL) composed of vinylene carbonate (VC) and lithium difluoro(oxalato)borate (LiDFOB) is proposed for both Ni-rich NCM and SiOx electrode materials. The LiDFOB additive individually delivers inorganic-rich cathode-electrolyte interphase (CEI) and solid-electrolyte interphase (SEI) layers in anodic and cathodic polarizations before the VC additive. Subsequently, the VC additive is capable of the formation of additional CEI and SEI layers composed of relatively organic-rich components through an electrochemical reaction; thus, inorganic-organic hybridized CEI and SEI layers are simultaneously formed at the Ni-rich NCM and SiOx electrodes. Accordingly, the VL-assisted electrolyte exhibits remarkably prolonged cycling retention for the Ni-rich NCM cathode (86.5%) and SiOx anode (72.7%), whereas the standard electrolyte shows a substantial decrease in cycling retention for the Ni-rich NCM cathode (59.2%) and SiOx anode (18.1%). Further systematic analyses prove that VL-assisted electrolytes form effective interphases for Ni-rich NCM and SiOx electrodes simultaneously, thereby leading to stable and prolonged cycling behaviors of LIBs that offer high energy densities.

Regulating electrostatic phenomena by cationic polymer binder for scalable high-areal-capacity Li battery electrodes.

Despite the enormous interest in high-areal-capacity Li battery electrodes, their structural instability and nonuniform charge transfer have plagued practical application. Herein, we present a cationic semi-interpenetrating polymer network (c-IPN) binder strategy, with a focus on the regulation of electrostatic phenomena in electrodes. Compared to conventional neutral linear binders, the c-IPN suppresses solvent-drying-induced crack evolution of electrodes and improves the dispersion state of electrode components owing to its surface charge-driven electrostatic repulsion and mechanical toughness. The c-IPN immobilizes anions of liquid electrolytes inside the electrodes via electrostatic attraction, thereby facilitating Li+ conduction and forming stable cathode-electrolyte interphases. Consequently, the c-IPN enables high-areal-capacity (up to 20 mAh cm-2) cathodes with decent cyclability (capacity retention after 100 cycles = 82%) using commercial slurry-cast electrode fabrication, while fully utilizing the theoretical specific capacity of LiNi0.8Co0.1Mn0.1O2. Further, coupling of the c-IPN cathodes with Li-metal anodes yields double-stacked pouch-type cells with high energy content at 25 °C (376 Wh kgcell-1/1043 Wh Lcell-1, estimated including packaging substances), demonstrating practical viability of the c-IPN binder for scalable high-areal-capacity electrodes.

Theoretical Protocol Based on Long-Range Corrected Density Functional Theory and Tuning of Range-Split Parameter for Two-Electron Two-Proton Reduction of Phenylazocarboxylates.

A theoretical protocol based on long-range corrected density functional theory is suggested for a highly accurate estimation of the two-electron two-proton (2e2p) reduction potential of ethyl 2-phenylazocarboxylate derivatives. Geometry optimization and single-point energy refinement with ωB97X-D are recommended. The impact of polarization and diffusion functions in the basis sets on the 2e2p reduction potential is discussed. Further improvements can be achieved by tuning the range-split parameter based on the linear relationship between the Hammett constant of phenyl substituents and the optimal ω value that most accurately reproduces the experiments. The suggested protocol can accurately predict the 2e2p reduction potential of five ethyl 2-phenylazocarboxylate derivatives. Based on these findings, 22 additional candidates are suggested to enlarge the electrochemical window and to increase the selectivity of 2e2p reactions. This study contributes to the development of a theoretical approach to accurately estimate the 2e2p reduction potential of azo groups.

Interface-Stabilized Layered Lithium Ni-Rich Oxide Cathode via Surface Functionalization with Titanium Silicate.

Nickel-rich lithium metal oxide cathode materials have recently be en highlighted as next-generation cathodes for lithium-ion batteries. Nevertheless, their relatively high surface reactivity must be controlled, as fading of the cycling retention occurs rapidly in the cells. This paper proposes functionalized nickel-rich lithium metal oxide cathode materials by a multipurpose nanosized inorganic material-titanium silicon oxide-via a simple thermal treatment process. We examined the topologies of the nano-titanium silicate-functionalized nickel-rich lithium metal oxide cathodes with scanning electron microscopy and quantitatively analyzed their improved mechanical properties using microindentation. The cell containing nickel-rich lithium metal oxide cathodes suffered from poor cycling behavior as the electrolytes persistently decomposed; however, this behavior was effectively inhibited in the cell by nano-titanium silicate-functionalized nickel-rich lithium metal oxide cathodes. Further ex situ analyses indicated that the particle hardness of the nano-titanium silicate-functionalized nickel-rich lithium metal oxide cathode materials was maintained, and decomposition of the electrolyte by the dissolution of transition metals was thoroughly inhibited even after 100 cycles. Based on these results, we concluded that the use of nano-titanium silicate as a coating material for nickel-rich lithium metal oxide cathode materials is an effective way to enhance the cycling performance of lithium-ion batteries.

Al-compatible boron-based electrolytes for rechargeable magnesium batteries.

Galvanic couple-assisted dissolution of Mg metal in an ethereal solution containing tris(2H-hexafluoroisopropyl)borate was utilized to prepare an efficient Al-compatible electrolyte for rechargeable Mg batteries. The electrolyte exhibited conditioning-free Mg deposition, high oxidative stability (3.5 V vs. Mg/Mg2+), and a superb electrochemical performance with various cathodes on an Al current collector.

A dataset of the thioacetmide supported formation of ZrO2 coating on Ni-rich layered structure cathode materials in lithium-ion batteries.

A dataset in this report is regarding a research article "Crucial Role of Thioacetamide for ZrO2 Coating on the Fragile Surface of Ni-rich Layered Cathode in Lithium Ion Batteries" [1]. Thioacetamide (TA) is introduced to form a homogeneous ZrO2-coating in a facile method through washing with Zr(SO4)2 aqueous solution. The presence of the data in this paper indicated the role of TA for surface modification of LiNi0.82Co0.09Mn0.09O2 (NCM82) materials by ZrO2, leading to improve the electrochemical performance of NCM82 Ni-rich cathode materials. These data were proceeded measurement electrochemical properties of cathode electrode on a battery cycler, the surface characteristics of the cathode materials were investigated by SEM, EDS mapping, TEM and XPS. X-ray diffraction (XRD, Rigaku, SmartLab) was used to evaluate the influence of the coating layer on the microstructure of active materials.

Amide-Functionalized Porous Carbonaceous Anode Materials for Lithium-Ion Batteries.

Porous carbonaceous anode materials have received considerable attention as an alternative anode material, however, there is a critical bottleneck as it suffers from a large irreversible specific capacity loss over several initial cycles owing to undesired surface reactions. In order to suppress undesired surface reactions of porous carbonaceous anode material, here, we suggest a simple and convenient two-step surface modification approach that allows the embedding of an amide functional group on the surface of a porous carbonaceous anode, which effectively improves the surface stability. In this approach, the porous carbonaceous anode material is firstly activated by means of strong acid treatment comprising a combination of H2 SO4 and HNO3 , and it is subjected to further modification by means of an amide coupling reaction. Our additional systematic analyses confirm that the acid functional group effectively transforms into the amide functional group. The resulting amide-functionalized porous carbon exhibits an improved electrochemical performance: the initial discharge specific capacity is greatly reduced to less than 2,620 mA h g-1 and charge specific capacity is well still remained, indicating stabling cycling performance of the cell.

Oxidation Potential Tunable Organic Molecules and Their Catalytic Application to Aerobic Dehydrogenation of Tetrahydroquinolines.

In this work, oxidation potential tunable organic molecules, alkyl 2-phenyl hydrazocarboxylates, were disclosed. The exquisite tuning of their oxidation potentials facilitated a catalytic dehydrogenation of 1,2,3,4-tetrahydroquinolines in the presence of Mn(Pc) and O2.

Two-Dimensional Phosphorene-Derived Protective Layers on a Lithium Metal Anode for Lithium-Oxygen Batteries.

Lithium-oxygen (Li-O2) batteries are desirable for electric vehicles because of their high energy density. Li dendrite growth and severe electrolyte decomposition on Li metal are, however, challenging issues for the practical application of these batteries. In this connection, an electrochemically active two-dimensional phosphorene-derived lithium phosphide is introduced as a Li metal protective layer, where the nanosized protective layer on Li metal suppresses electrolyte decomposition and Li dendrite growth. This suppression is attributed to thermodynamic properties of the electrochemically active lithium phosphide protective layer. The electrolyte decomposition is suppressed on the protective layer because the redox potential of lithium phosphide layer is higher than that of electrolyte decomposition. Li plating is thermodynamically unfavorable on lithium phosphide layers, which hinders Li dendrite growth during cycling. As a result, the nanosized lithium phosphide protective layer improves the cycle performance of Li symmetric cells and Li-O2 batteries with various electrolytes including lithium bis(trifluoromethanesulfonyl)imide in N,N-dimethylacetamide. A variety of ex situ analyses and theoretical calculations support these behaviors of the phosphorene-derived lithium phosphide protective layer.

Tris(trimethylsilyl) Phosphite as an Efficient Electrolyte Additive To Improve the Surface Stability of Graphite Anodes.

Tris(trimethylsilyl) phosphite (TMSP) has received considerable attention as a functional additive for various cathode materials in lithium-ion batteries, but the effect of TMSP on the surface stability of a graphite anode has not been studied. Herein, we demonstrate that TMSP serves as an effective solid electrolyte interphase (SEI)-forming additive for graphite anodes in lithium-ion batteries (LIBs). TMSP forms SEI layers by chemical reactions between TMSP and a reductively decomposed ethylene carbonate (EC) anion, which is strikingly different from the widely known mechanism of the SEI-forming additives. TMSP is stable under cathodic polarization, but it reacts chemically with radical anion intermediates derived from the electrochemical reduction of the carbonate solvents to generate a stable SEI layer. These TMSP-derived SEI layers improve the interfacial stability of the graphite anode, resulting in a retention of 96.8% and a high Coulombic efficiency of 95.2%. We suggest the use of TMSP as a functional additive that effectively stabilizes solid electrolyte interfaces of both the anode and cathode in lithium-ion batteries.

Effect of Silyl Ether-functinoalized Dimethoxydimethylsilane on Electrochemical Performance of a Ni-rich NCM Cathode.

Dimethoxydimethylsilane (DODSi) is used as an interface stabilizing additive through a selective HF scavenging reaction for layered Ni-rich oxide cathodes. Ex situ NMR analyses demonstrated that DODSi effectively removes HF from the electrolyte based on the matched chemical reactivity of Si with F- and O with H+ . The cells employing DODSi exhibit higher specific capacity with retention than those cycled with a DODSi-free electrolyte even under in situ HF generating conditions. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma-mass spectroscopy (ICP-MS) analyses indicate that DODSi effectively protects the Ni-rich oxide cathodes against HF corrosion, resulting in improved surface stability of Ni-rich cathodes.

A joint experimental and theoretical determination of the structure of discharge products in Na-SO2 batteries.

Na-SO2 batteries are promising power sources for energy storage systems. However, it is unclear what happens on the cathode surface at the molecular level during the discharge process. Here, we provide the working mechanism of Na-SO2 batteries through a combination of nuclear magnetic resonance (NMR) spectroscopy and first-principles NMR calculations.

Physically Cross-linked Polymer Binder Induced by Reversible Acid-Base Interaction for High-Performance Silicon Composite Anodes.

Silicon is greatly promising for high-capacity anode materials in lithium-ion batteries (LIBs) due to their exceptionally high theoretical capacity. However, it has a big challenge of severe volume changes during charge and discharge, resulting in substantial deterioration of the electrode and restricting its practical application. This conflict requires a novel binder system enabling reliable cyclability to hold silicon particles without severe disintegration of the electrode. Here, a physically cross-linked polymer binder induced by reversible acid-base interaction is reported for high performance silicon-anodes. Chemical cross-linking of polymer binders, mainly based on acidic polymers including poly(acrylic acid) (PAA), have been suggested as effective ways to accommodate the volume expansion of Si-based electrodes. Unlike the common chemical cross-linking, which causes a gradual and nonreversible fracturing of the cross-linked network, a physically cross-linked binder based on PAA-PBI (poly(benzimidazole)) efficiently holds the Si particles even after the large volume changes due to its ability to reversibly reconstruct ionic bonds. The PBI-containing binder, PAA-PBI-2, exhibited large capacity (1376.7 mAh g(-1)), high Coulombic efficiency (99.1%) and excellent cyclability (751.0 mAh g(-1) after 100 cycles). This simple yet efficient method is promising to solve the failures relating with pulverization and isolation from the severe volume changes of the Si electrode, and advance the realization of high-capacity LIBs.

A room-temperature sodium rechargeable battery using an SO2-based nonflammable inorganic liquid catholyte.

Sodium rechargeable batteries can be excellent alternatives to replace lithium rechargeable ones because of the high abundance and low cost of sodium; however, there is a need to further improve the battery performance, cost-effectiveness, and safety for practical use. Here we demonstrate a new type of room-temperature and high-energy density sodium rechargeable battery using an SO2-based inorganic molten complex catholyte, which showed a discharge capacity of 153 mAh g(-1) based on the mass of catholyte and carbon electrode with an operating voltage of 3 V, good rate capability and excellent cycle performance over 300 cycles. In particular, non-flammability and intrinsic self-regeneration mechanism of the inorganic liquid electrolyte presented here can accelerate the realization of commercialized Na rechargeable battery system with outstanding reliability. Given that high performance and unique properties of Na-SO2 rechargeable battery, it can be another promising candidate for next generation energy storage system.

Self-Extinguishing Lithium Ion Batteries Based on Internally Embedded Fire-Extinguishing Microcapsules with Temperature-Responsiveness.

User safety is one of the most critical issues for the successful implementation of lithium ion batteries (LIBs) in electric vehicles and their further expansion in large-scale energy storage systems. Herein, we propose a novel approach to realize self-extinguishing capability of LIBs for effective safety improvement by integrating temperature-responsive microcapsules containing a fire-extinguishing agent. The microcapsules are designed to release an extinguisher agent upon increased internal temperature of an LIB, resulting in rapid heat absorption through an in situ endothermic reaction and suppression of further temperature rise and undesirable thermal runaway. In a standard nail penetration test, the temperature rise is reduced by 74% without compromising electrochemical performances. It is anticipated that on the strengths of excellent scalability, simplicity, and cost-effectiveness, this novel strategy can be extensively applied to various high energy-density devices to ensure human safety.

Surface modification of sulfur electrodes by chemically anchored cross-linked polymer coating for lithium-sulfur batteries.

Lithium-sulfur batteries suffer from severe self-discharge due to polysulfide dissolution into electrolytes. In this work, a chemically anchored polymer-coated (CAPC) sulfur electrode was prepared, through chemical bonding by coordinated Cu ions and cross-linking, to improve cyclability for Li/S batteries. This electrode retained specific capacities greater than 665 mAh g(-1) at high current density of 3.35 A g(-1) (2C rate) after 100 cycles with an excellent Coulombic efficiency of 100%.

The effect of an elastic functional group in a rigid binder framework of silicon-graphite composites on their electrochemical performance.

As a means of enhancing the electrochemical performance of silicon-graphite composites, we propose a novel binder candidate that is modified by a combination of rigid and elastic functional groups on its binder framework. To provide an efficient binder that is also capable of rapid volume changes, a co-polymer binder (PAA-PAA/PMA) is synthesized by employing poly(acrylic acid) (PAA) as the main binder framework and poly(acrylic acid)-co-poly(maleic acid) (PAA/PMA) as an additional elastic polymer auxiliary. This co-polymer binder (PAA-PAA/PMA) affords a good balance of adhesive and mechanical (rigidity and elasticity) properties, which creates an excellent cycle performance with a high specific capacity (751.1 mA h g(-1)) and considerable capacity retention (64.9%) after 300 cycles. This is attributed to the ability of the added elastic functional group to respond flexibly to volume changes, thereby enhancing the overall uniformity of the electrode and ensuring a consistent electronic network. On the basis of these findings, it is considered that embedding an elastic functional group into the binder framework is an effective approach to improve the overall performance of Si-graphite composite electrodes.

A new strategy for integrating abundant oxygen functional groups into carbon felt electrode for vanadium redox flow batteries.

The effects of surface treatment combining corona discharge and hydrogen peroxide (H2O2) on the electrochemical performance of carbon felt electrodes for vanadium redox flow batteries (VRFBs) have been thoroughly investigated. A high concentration of oxygen functional groups has been successfully introduced onto the surface of the carbon felt electrodes by a specially designed surface treatment, which is mainly responsible for improving the energy efficiency of VRFBs. In addition, the wettability of the carbon felt electrodes also can be significantly improved. The energy efficiency of the VRFB cell employing the surface modified carbon felt electrodes is improved by 7% at high current density (148 mA cm(-2)). Such improvement is attributed to the faster charge transfer and better wettability allowed by surface-active oxygen functional groups. Moreover, this method is much more competitive than other surface treatments in terms of processing time, production costs, and electrochemical performance.

Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries.

Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25 nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses.

Ceramic composite separators coated with moisturized ZrO(2) nanoparticles for improving the electrochemical performance and thermal stability of lithium ion batteries.

We introduce a ceramic composite separator prepared by coating moisturized ZrO2 nanoparticles with a poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-12wt%HFP) copolymer on a polyethylene separator. The effect of moisturized ZrO2 nanoparticles on the morphology and the microstructure of the polymeric coating layer is investigated. A large number of micropores formed around the embedded ZrO2 nanoparticles in the coating layer as a result of the phase inversion caused by the adsorbed moisture. The formation of micropores highly affects the ionic conductivity and electrolyte uptake of the ceramic composite separator and, by extension, the rate discharge properties of lithium ion batteries. In particular, thermal stability of the ceramic composite separators coated with the highly moisturized ZrO2 nanoparticles (a moisture content of 16 000 ppm) is dramatically improved without any degradation in electrochemical performance compared to the performance of pristine polyethylene separators.