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Zero-valent antimony and antimony oxide were deposited on graphene oxide by the recently introduced peroxide deposition route. The antimony@graphene oxide (GO) anode exhibits a charging capacity of 340 mAh g-1 with excellent stability at a current rate of 250 mA g-1 after 50 cycles of lithiation, which is superior to all other forms of antimony anodes that have been reported thus far. The electrode also exhibits a good rate performance, with a capacity of 230 and 180 mAh g-1 at a rate of 500 and 1000 mA g-1, respectively. We attribute the superior performance of the antimony@GO anodes to our coating protocol, which provides a thin layer of nanometric antimony coating on the graphene oxide, and to a small amount of antimony oxide that is left in the anode material after heat treatment and imparts some flexibility. The efficient charge distribution by the large surface area of reduced GO and the expansion buffering of the elastic graphene sheets also contributed to the superior stability of the anode.

Thin films of copper, with thickness between 0.1 and 3 mum, are vapor-deposited on 12.7 or 7.6-mum-thick polyimide (Kapton) substrates, are tested in a microtensile tester in which the strain is measured by optical diffraction from a microlithographically applied grid. It is found that the yield stress depends strongly on the film thickness and is fit by sigma(sub y) = 116 + 355(t)(super -0.473, where t is the thickness in mum and sigma(sub y) is in MPa.

Abstract: Electrochemical performance of Cu2MoS4 was evaluated. When the cutoff potential is limited between 1.6 and 3.0V, the material can give stable cycle performance of up to 100mAhg−1. However, the material shows slow kinetics within this region. The material can give a discharge capacity of up to 653mAhg−1 when discharged to 0.6V vs. Li/Li+, with a first cycle efficiency of 61.3%. This corresponds to an insertion of 8.5Li and an extraction of 5.2Li from the material. XRD and XPS measurements both suggest Cu displacement from the material during discharge and charge, which is a possible reason for the poor cycle stability of the material. A reaction mechanism is proposed based on the XPS analysis. Better cycle performance is observed for Cu2MoS4/GO composite. [Copyright &y& Elsevier]

Abstract: Co3O4 nanoparticles are grown on nitrogen modified microwave exfoliated graphite oxide (NMEG) with weight ratio controlled from 10% to 70%. Electrochemical performance reveals that the obtained Co3O4/NMEG composite as Li-ion battery anode exhibits improved cycle stability, excellent reversible capacity, high current rate performance, and reduced irreversible capacity loss in the initial cycle compared to pure Co3O4 without graphene or Co3O4 on thermally reduced graphene oxide (tRG-O). The 70%Co3O4/NMEG composite has initial irreversible capacity of 230mAhg−1 (first cycle efficiency of 77%), and 910mAhg−1 of capacity is retained after 100 cycles. The 70%Co3O4/tRG-O delivers a reversible capacity of 750±20mAhg−1, and the irreversible capacity loss during the first cycle is 700±20mAhg−1. Nitrogen functional groups in NMEG, especially pyridinic and pyrrolic N are advantageous for the Co3O4 growth. Furthermore, the N modification is effective in reducing the oxygen content of chemically prepared graphene and hence is good for Co3O4 dispersion and the amelioration of first cycle efficiency, demonstrating the potential of NMEG based composite as high performance Li-ion battery anode materials. [Copyright &y& Elsevier]

Free-standing polycrystalline films of Ag, Cu and Ag/Cu multilayers were tested in tension using an optical diffraction grating for the measurement of the strain. The yield stress and the rate of work hardening both increase strongly with decreasing layer thickness. These effects combine to raise the stress for ductile fracture up to 700 MPa and to lower the maximum plastic strain. [ABSTRACT FROM AUTHOR]

Abstract Traditional sodium-ion battery cathodes utilize the change in oxidation state of the transition metal(s) in the structure to accommodate the electron transfer during charge and discharge. Recent researches on sodium-rich compounds such as Na 2 RuO 3 and Na 2 IrO 3 suggest that anionic reaction with oxygen can be an additional source of electrons during electrochemical reactions. Here we demonstrate for the first time that stoichiometric NaVO 3 , despite the valence of vanadium of 5+, delivers a reversible capacity by activating it beyond 4.5 V. Elemental analysis confirms Na removal and insertion from/into NaVO 3 during charge/discharge. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy results show that the oxidation state of vanadium remains unchanged, while oxygen is likely to compensate for the charge transfer during charge/discharge. Theoretical calculation on spin density of electrons in the lattice also supports the involvement of oxygen during sodium removal. Our demonstration of the unique behaviors of NaVO 3 provides a new exciting direction for research in sodium-ion battery cathodes. Highlights • NaVO 3 can be charged despite vanadium in its highest oxidation state. • Capacity of NaVO 3 depends strongly on particle size and electrical conductivity. • NaVO 3 undergoes reversible charge-discharge after activation. • NaVO 3 maintains its crystal structure upon charge and discharge. • Theoretical calculation suggests the involvement of oxygen during sodium removal. [ABSTRACT FROM AUTHOR]

Recently, aqueous rechargeable zinc-ion batteries (AZIBs) have attracted much attention owing to their low cost and intrinsic safety. However, the reversibility of AZIBs is limited by dendrite growth on the Zn anode, which leads to low Coulombic efficiency and potential short circuit during cycling. Herein, we develop a new strategy using electrostatic shielding to enable a highly reversible Zn anode. Specifically, a cationic polymeric ionic liquid (PIL) coating layer with a strong positive charge evens out the charge distribution on the surface of the Zn electrode, enabling uniform stripping and deposition of Zn. As a result, a symmetric Zn–Zn cell can sustain stripping-plating for over 2000 h at 1 mA cm−2 with a capacity limit of 1 mAh cm−2, far exceeding the performance of bare Zn electrode. A highly reversible Zn stripping-plating on Cu substrate is also achieved with an average coulombic efficiency of 99.5% over 1100 cycles. PILZ layer can even allow a uniform Zn deposition of up to 30 μm thick, allowing large utilization of the Zn foil. Moreover, the coating layer enables the stable cycling of a MnO 2 –Zn full cell with a high areal capacity of 1 mAh cm−2. [Display omitted] • A functional polymeric interfacial layer is designed to suppress Zn dendrite. • The layer shields the surface electrostatically to enable uniform Zn deposition. • In-situ microscopy shows high utilization of Zn with uniform deposition. • Achieved reversible stripping-plating with high efficiency. • Demonstrated MnO 2 –Zn full cell with high areal loading and long cycle. [ABSTRACT FROM AUTHOR]

Thermal stability of a lithium-rich layered oxide cathode material with composition 0.5Li 4/3 Mn 2/3 O 2 –0.5LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LMO–NCM) is investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Investigated material shows higher thermal stability (higher onset temperature) than LiCoO 2 . The state of charge and previous cycling history of LMO–NCM, particularly activation of lithium manganese oxide (LMO) “component” during first charge, affect its thermal stability. Activation of LMO has an ambivalent effect on cathode thermal stability: on the one hand, the onset temperature of cathode decomposition is increased, probably due to the change in oxidation states of Ni, Co and Mn after the first cycle. On the other hand, the enthalpy of decomposition increases, presumably due to formation of unstable oxygen in the lattice. X-ray diffraction (XRD) analyses of cathodes before and after thermal decomposition at 600 °C indicate differences in decomposition reactions of charged cathodes, depending on state of charge and cycling history. [ABSTRACT FROM AUTHOR]

Abstract: Thermal stability of charged LiCoO2 cathodes with various surface areas of active material is investigated in order to quantify the effect of LiCoO2 surface area on thermal stability of cathode. Thermogravimetric analyses and calorimetry have been conducted on charged cathodes with different active material surface areas. Besides reduced thermal stability, high surface area also changes the active material decomposition reaction and induces side reactions with additives. Thermal analyses of LiCoO2 delithiated chemically without any additives or with a single additive have been conducted to elaborate the effect of particle size on side reactions. Stability of cathode–electrolyte system has been investigated by accelerating rate calorimetry (ARC). Arrhenius activation energy of cathode decomposition has been calculated as function of conversion at different surface area of active material. [Copyright &y& Elsevier]

Dual-ion battery (DIB) can potentially provide higher power, lower cost and faster charging capability than traditional lithium-ion batteries. Even though graphite can effectively accommodate anions as a cathode for DIB, the high working voltage of around 5 V vs. Li/Li+ leads to continuous side reactions, yielding to low Coulombic efficiency (CE < 90%) and poor cycle life. Here, we demonstrate that fluoroethylene carbonate (FEC) additive can induce a protective cathode electrolyte interface (CEI) on the graphite cathode, effectively suppressing electrolyte decomposition and stabilizing the graphite surface. This CEI enables a high CE (~99.0%) and an excellent cycle stability of 5000 cycles with capacity retention of 85.1% at the cutoff voltage of 5.1 V. The CEI layer can also reduce the self-discharge of the battery. Furthermore, the DIB exhibits a high-rate capability with 93.3% utilization at 30C (3000 mA g−1), enabling an ultrafast charging time within two minutes. This work sheds light on the features of CEI on graphite cathodes and provides a facile and economically effective strategy to achieve highly reversible/stable cycling of DIBs with high power capability. Image 1 • A protective cathode electrolyte interface is constructed on the graphite cathode. • The graphite surface is effectively stabilized for PF 6 − de-/intercalation process. • The cathode electrolyte interface significantly suppresses electrolyte decomposition. • The graphite-based dual-ion batteries with FEC additive exhibits low self-discharge. • Highly reversible/stable cycling and ultrahigh power capability are achieved. [ABSTRACT FROM AUTHOR]

Binder plays a key role in maintaining the integrity of battery electrodes. In this work, we investigate the relationship between binder properties and performances of Si electrodes in a lithium-ion battery (LIB). We learn from nature and use borax as a crosslinker between strands of polyacrylic acid (PAA) to form a network in the binder. By adding different amounts of borax, we can control the degree of crosslinking and thus the mechanical and chemical properties of the binder. We find that increasing the amount of borax crosslinker increases the modulus of the polymer network and the stability of the corresponding Si electrode up to about 5 wt% borax. Even with Si microparticles with an electrode density of 1.25 g cm−3, we obtain a capacity of about 2470 mA h g−1 (3.1 mA h cm−2) and a capacity retention of 91.2% after 50 cycles. Cycle performance is extended beyond 500 cycles with a capacity limitation of 1000 mA h g−1. Though, excessive amount of borax consumes the functional groups of PAA and compromises electrode adhesion, resulting in a decrease in cycle stability. Striking a balance between mechanical strength and adhesion of the binder is important for further development of alloy-based anode materials for LIBs. PAA-borax crosslinked polymer provides high mechanical strength and enables high areal capacity anode using bulk Si as active material. Image 1 • PAA binder can be crosslinked with the addition of borax. • Crosslinking increases modulus and hardness of the polymer binder. • Use of micron-sized Si particles enables electrode with high packing density of 1.25 g cm−3 • Excellent cycle stability obtained for micron-sized Si with 5 wt% borax in PAA. • A tradeoff between binder strength and electrode adhesion is observed. [ABSTRACT FROM AUTHOR]

Silicon monoxide (SiO) with a high Li storage capacity is an attractive material for next-generation lithium-ion batteries. Though, micron-size SiO, which is easier to handle and manufacture, undergoes particle cracking during charge and discharge, leading to fast capacity fading. In this work, we design a robust coating system to accommodate the large volume change of the SiO particles using a self-assembled monolayer (SAM) to covalently bond the active material with a high-modulus polyimide (PI) coating. The SAM is essential as it enhances the adhesion between the particles and the coating, preventing the delamination of the PI coating. The SiO material with the coating demonstrates a stable capacity of 1310.7 mAh g−1 under a current rate of 150 mA g−1 for 100 cycles. The electrode is stable even for 300 cycles at a current rate of 1000 mA g−1. Full cell test with LiFePO 4 positive electrode also shows stable cycle performance with 86% capacity retention after 200 cycles. • Micron-sized SiO particles coated with self-assemble monolayer and polyimide. • Self-assemble monolayer covalently bonded with surface of SiO and polyimide. • Coating system reduces thickness change of electrode during charge and discharge. • Cycle stability significantly improved with coating system. • Stability is verified by full cell tests. [ABSTRACT FROM AUTHOR]