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In this paper, WO 3 uniformly coated LiNi 0.9 Co 0.05 Mn 0.05 O 2 cathode materials are prepared by wet coating method using ammonium metatungstate as tungsten source. The XRD, SEM, and XPS tests show that the cladding process introduced W ions into the NCM lattice, increasing the layer spacing and improving the lithium diffusion rate. The charge/discharge test results indicate that a moderate amount of WO 3 coating can enhance the rate-discharge performance and increase the long cycle life. After 100 cycles at 1C (180 mAh g−1), the reversible capacity of the material containing 0.5wt% WO 3 coating is 157.9 mAh g−1, while that of the original material is only 130.9 mAh g−1, which indicates that the WO 3 coating protects the cathode material from HF corrosion, thus improving the stability of the structure. DFT calculations show that the dangling bonds of O on the NCM surface are highly susceptible to binding with W, which reduces the possibility of WO 3 coating exfoliation.WO 3 and NCM are p-type semiconductors and semi-metallic materials, respectively, which form ohmic contacts at heterogeneous interfaces thereby increasing the electronic conductivity of the materials, and due to the synergistic effect, the diffusion barrier of Li near the heterogeneous interfaces is lower than that of the pristine materials. [ABSTRACT FROM AUTHOR]

• S-PANI coating for Zn anode is prepared by a simple and low-cost method. • The synergistic effect of N elements and sulfonic acid groups in SPANI coating layer could induce the uniform zinc deposition. • The Zn anode with S-PANI coating can achieve a desired reversible and stability. • The full battery using SPANI@Zn anode shows a good rate and cycling performance. Designing the performance of artificial solid electrolyte interphase (ASEI) is critical for addressing issues at the Zn anode-electrolyte of aqueous zinc batteries (AZBs). Inspired by the anti-corrosion strategy of metal substrate, a self-doping sulfonated polyaniline (S-PANI) is constructed on the surface of zinc foil by a facile scraping method. The synergistic effect of nitrogen and sulfonic acid groups in S-PANI coating layer, accompanies microchannels in the polymer network is favorable for the fast Zn2+ ion transport, uniform and stable Zn deposition. As a result, the Zn anode with S-PANI coating can achieve high average coulombic efficiency of 98.0% over 150 cycles and superior cycling performance up to 1500 h at a 0.5 mA cm-2 and 0.5 mAh cm-2. Moreover, the full battery coupled with PTO organic cathode also demonstrates superior cycling stable performance. This work opens effective approach for the application of conductive polymer coating in Zn anode protection. A polymer coating is used to prevent the side reactions and inhibit the generation of zinc dendrites resulting in the uniform deposition of Zn2+, thereby improving the stability of the anode electrode in aqueous rechargeable zinc batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

• Fabricate the rGO/PVDF@PP separator through one-side coating. • The 3D porous structure coating formed by rGO and PVDF enhances the wettability of the electrolyte. • Li‖Li symmetric battery can stably cycle for 1000 h at 0.5 mA cm-2 without short circuit. • The XPS analysis results indicate that the rGO/PVDF@PP separator facilitates the uniform deposition of lithium ions, thereby stabilizing the SEI. Lithium metal anode is broadly regarded as one of the most promising anode materials for batteries due to its extremely high specific capacity, very low redox potential, and mass density. Nevertheless, non-uniform deposition of lithium ions hinder the practical application of lithium metal batteries (LMBs). Herein, it was essential to design a separator with high electrolyte affinity to inhibit the non-uniform deposition of lithium ions. In this work, the wettability and electrolyte uptake of the polypropylene (PP) separator were remarkably improved by introducing reduced graphene oxide (rGO) and polyvinylidene fluoride (PVDF) to the surface of the separator through one-sided coating. The composite separator resulted in lithium ion with high conductivity (1.35 × 10–3 S cm-1) and transfer number (0.63). After assembling the rGO/PVDF@PP separator into the LiFePO 4 ||Li battery and conducting the test, it was found that the specific discharge capacity could still reach 136 mAh g-1 after 100 cycles at 1C. Furthermore, After 1000 h of cycling in the assembled Li‖Li symmetric battery, there is no obvious generation of lithium dendrites on the surface of the lithium metal, indicating the successful suppression of lithium dendrites by the composite separator. This study offers a promising pathway for producing large quantities of new composite separators with high levels of safety. [Display omitted] [ABSTRACT FROM AUTHOR]

Micron-silicon based material is a promising anode material for high performance lithium batteries due to its ultra-high specific capacity. However, the volume expansion exceeds 300 % during charging and discharging, resulting in the collapse of the electrode structure and a rapid decline in electrochemical performance. Coating the surface of silicon-based materials with flexible ionic conductors is an effective method to maintain their high capacity and suppress swelling. Here, to further improve the electrochemical performance of silicon-based materials, we have deposited a titanate-type ionic conductor layer on a micron-sized silicon-carbon oxide (SiO X -C) material to synthesize the SiO X -C@TiO x (OH) y material. The TiO x (OH) y layer not only exhibits the elastic properties of a superpolymer to mitigate swelling strain, but also has a fast capacitance effect to improve its rate performance. In addition, the interfacial charge transport of SiO X -C@TiO x (OH) y is enhanced due to the structural diversity of the TiO x (OH) y layer. For the above mechanisms, the SiO X -C@TiO x (OH) y has a specific capacity of 278.3 mAh g −1 under high current of 3500 mA g −1. Meanwhile, the SiO X -C@TiO x (OH) y with the capacity retention of 67 % is achieved at 2000 mA g −1 after 100 cycles. [Display omitted] [ABSTRACT FROM AUTHOR]

Bio-inspired superhydrophobic coatings are of increasing interest in marine corrosion protection due to their superior barrier and shielding effects. However, some difficult problems like weak mechanical strength, the use of costly and toxic reagents, and intricate preparation processes have long hindered the practical application of the superhydrophobic coatings. Herein, a durable, self-cleaning and anti-corrosion superhydrophobic coating based on epoxy resin matrix was successfully fabricated, avoiding the use of fluorine materials. The prepared coating possessed excellent superhydrophobicity and was applicable to a variety of substrates, which was ascribed to the effect of modified kaolin particles on lowering surface energy. Through SEM and LSCM, the superhydrophobic coatings manifested the morphology feature of "hills+mountain", which could store air to reduce solid-liquid contact. The prepared coating had been proven to have greater impedance modulus and charge transfer resistance by EIS test, and displayed outstanding durability in salt spray environment compared with pure epoxy coating. In addition, the sandpaper abrasion, standard cross-cut tape and self-cleaning tests indicated that the superhydrophobic coatings satisfied robust mechanical stability and excellent resistance to contaminants, laying the foundation for the application of superhydrophobic coating in practical environment. [ABSTRACT FROM AUTHOR]

Layered Co-free Ni-rich materials are considered as promising cathode for lithium-ion batteries (LIBs) due to their high energy density and low cost advantages. However, the serious chemical-mechanical instability and poor cycle life of Co-free Ni-rich cathode materials could hinder their commercialization. Herein, we successfully prepared Mg/Ti/Sb co-doped and CeO 2 -coated LiNi 0.9 Al 0.1 O 2 cathode material (M-LNA90) using a composite modification strategy with four inexpensive metal elements. Compared with the unmodified pristine LiNi 0.9 Al 0.1 O 2 cathode material (P-LNA90), the cycling stability, rate performance, and discharge capacity of the M-LNA90 cathode were significantly improved, and the high-voltage performance was also excellent. At a high voltage of 2.8–4.5 V and 1 C, the capacity retention of M-LNA90 after 100 cycles reached 90.2 % (from 200 mAh g–1 to 181 mAh g–1), which was much higher than that the 60.1 % of P-LNA90 (from 192 mAh g–1 to 115 mAh g–1). Meanwhile, the structure and surface stability of M-LNA90 cathode showed excellent, which effectively suppressed particle cracking and interfacial side reactions. This work provides a new insight for the composition optimization and future design of layered Ni-rich cathode materials. [ABSTRACT FROM AUTHOR]

Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) is a promising cathode for intermediate temperature solid oxide fuel cells. However, BSCF cathode performance stability has been a challenge and its electrochemical performance deteriorates severely in the presence of Cr 2 O 3 -forming metallic interconnect. We demonstrate that LaCoO 3-δ (LC) coating on BSCF cathode can not only enhance BSCF electrochemical performance, but also effectively improve the BSCF performance stability. In this study, LC-coated BSCF-Gd 0.1 Ce 0.9 O 1.9 (LC@BSCF-GDC) cathode is prepared through a solution impregnation method and systematically characterized. EIS, XRD, Raman, SEM and EDS tests with and without SUS430 interconnect are conducted to characterize the Cr-tolerance. The results show that BSCF-GDC cathode is susceptible to Cr poisoning while LC@BSCF-GDC cathode has significantly enhanced tolerance to Cr poisoning. Single cells with LC@BSCF-GDC cathode achieve higher peak power density and smaller polarization resistance values than single cells with BSCF-GDC cathode. Furthermore, significant improvement of performance stability under a constant current load has been achieved for single cells with LC@BSCF-GDC cathode. This work provides a new solution for solving BSCF cathode performance stability. [ABSTRACT FROM AUTHOR]

Lithium magnesium silicate (LMS) exhibits strong adsorbability, cohesiveness, suspensibility, chemical stability and good cation exchangeability, which was chosen in this work to modify Li 2 ZnTi 3 O 8 (LZTO) by simply mixing LZTO in LMS colloidal solution, followed by sintering at 750 °C for 5 h. The uniform LMS coating on LZTO particles gives rise to the marked enhancement in electrochemical performance of LZTO. The LMS-coated LZTO with a LMS/LZTO mass ratio of 0.015 achieves a high reversible capacity of 236.3 mAh g−1 at 100 mA g−1, which also demonstrates outstanding rate performance, attaining capacities of 243.3, 217.2, 200.5, 183.5, 140.4 and 269.8 mAh g−1 at the current rates of 100, 200, 400, 800, 1600 and 100 mA g−1. The appreciable performance is attributable to the uniform LMS coating for protecting LZTO against the direct contact with the electrolyte to refrain from the side reactions, enhancing the Coulombic efficiency in the initial cycle, improving electronic and ionic conductivities to weaken polarization by the interaction between LMS and electrolyte. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Na 3 V 2 (PO 4) 2 F 3 is considered to be a prospective candidate cathode for sodium ion batteries owing to its high operating voltage and excellent structural stability. However, the cycle performance together with rate capability of Na 3 V 2 (PO 4) 2 F 3 has been restrained on account of its low electronic conductivity. In this work, a series of carbon-coated Na 3 V 2 (PO 4) 2 F 3 samples were fabricated by utilizing a facile one-step carbothermal reduction method. The well crystallized Na 3 V 2 (PO 4) 2 F 3 /C showed good capacity performance where it delivered an initial discharge capacity of 112.3 mAh g−1 at 1C rate with a high retention of 89.7% after 100 cycles. Even at the current rate of 8C, it could give a capacity of 64 mAh g−1. The cycle stability of Na 3 V 2 (PO 4) 2 F 3 /C at the high temperature of 55 °C was also demonstrated. Besides, the Na 3 V 2 (PO 4) 2 F 3 /C showed good long-term durability, of which the capacity loss averaged 0.0264% per cycle at 2C rate at room temperature. Furthermore, the electrochemical impedance spectroscopy well explained the difference about the electrochemical performance of different Na 3 V 2 (PO 4) 2 F 3 /C samples. More importantly, Na 3 V 2 (PO 4) 2 F 3 /C is of great competence to serve as cathode for future sodium ion batteries applied in energy storage systems, and this simple one-step carbothermal reduction strategy to get Na 3 V 2 (PO 4) 2 F 3 /C will make contributions to accelerating this process. [ABSTRACT FROM AUTHOR]

Abstract In terms of the unique features of good suspensibility in water, superior absorbability, adhensivity, cation exchangeability and rapid ion diffusion channels, lithium magnesium silicate (LMSO) might be an appropriate modifier for Li 4 Ti 5 O 12 (LTO) by simply forming coating on LTO particles. According to a series of comparative experiments performed under various conditions, when the mixture of LTO and LMSO was roasted at 700 °C to form LMSO-coated LTO, the rate properties were significantly boosted (attaining cycling capacities of 160.2, 157.8, 155.8, 151.3 and 145.5 mAh g−1 with multiplying current density from 0.1 to 1.6 A g−1). Upon cycling at 0.5 A g−1 for 900 cycles, a capacity of 140.6 mAh g−1 was maintained. Compared to the pristine LTO, the markedly boosted rate properties and cyclability are ascribed to the LMSO coating for suppressing grain aggregation and growth, the optimized Li+ and electron transfer in electrolyte by interacting with LMSO, the enhanced electronic conductivity of LTO resulted from superficial co-doping of Mg2+ and Si4+, the meliorated ionic conductivity associating with the Li+ diffusion channels and cation exchangeability of LMSO, as well as the diminished polarization after the modification by LMSO. [ABSTRACT FROM AUTHOR]

Lithium-Sulfur (Li-S) technology has emerged as an alternative for the current market dominating lithium-technology for certain applications. In this work, pouch cells were produced using a straightforward protocol with PEDOT-coated sulfur particles as active material in the positive electrode. 1.45 Ah Li–S pouch cells consisting of five double-side coated cathodes and six lithium metal foil anodes, were designed and assembled. The obtained gravimetric energy density was 400 Wh/kg at a current density of 0.167 mA/mg sulfur i.e., C/10. The cell showed a limited loss of capacity until C-rate of C/2.5 with an energy retention superior to 80%, but dropped to 26% at 1C rate. In addition, the cell retained 70% of the initial capacity after 50 cycles at C/10. It was observed an initial activation period during which contact resistance drops due to the enhancement in the contact area for the sulfur/electrolyte and sulfur/carbon interfaces. The cell aging dynamics followed a two-step scenario with an initial limited capacity fading of -6.98 mAh/cycle (-0.5%/cycle) until the 30th cycle that was later doubled to -15.57 mAh/cycle (-1.1%/cycle). Electrochemical investigations suggest a transitory regime ruled by Fick's second law at the surface of the electrodes with the appearance and growing of a third plateau during the successive galvanostatic discharges. This phenomenon was attributed to an insufficient Li-ion transport inside the electrolyte, becoming continuously more limiting with extended cycling, and caused by the reactivity of a standard ether-based electrolyte with the Li-metal electrode. Electrochemical impedance spectroscopy (EIS) of the fully charged cells reveals a non-monotonic evolution of the cell impedance during the extended cycling tests. The ohmic resistance increases during the first twenty cycles suggest an increase of the polysulfide concentration in the electrolyte, which are thereafter stabilized for the remaining cycles. [ABSTRACT FROM AUTHOR]

Abstract Garnet-type Li 7 La 3 Zr 2 O 12 solid electrolytes were commonly prepared by two steps solid-state reaction method, which undergoes high temperature over 1000 °C and thus inevitable for lithium volatilization and formation of secondary phases. Here, we propose a new intergrain architecture engineering of a solution method, to avoid high temperature sintering for preparing lithium halide (LiX) coated garnet-type solid electrolytes, which contain Al and Ta co-doped Li 7 La 3 Zr 2 O 12 (Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , LLZTO) synthesized at 900 °C with cubic structure. Owing to the increased relative density, the improved formability, and the altered ion transport mode from point to face conduction by LiX coating on LLZTO grains, LiX-coated LLZTO samples demonstrate a good Li dendrite suppression ability and a high ionic conductivity that is three orders of magnitude higher than pristine LLZTO. In another way, this result demonstrates the critical role of the grain boundaries on the ion transport for oxide superionic conductors. The present coating method provides a new strategy to prepare brittle solid electrolytes avoiding high temperature sintering. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

The reduction mechanism of Cr(III) depends on the nature of the complexing agent present in electroplating solutions. In pure water solutions and without any other additives, Cr (III) is complexed with water molecules, creating a stable [Cr(H 2 O) 6 ] 3+ complex. [Cr(H 2 O) 6 ] 3+ can be reduced to Cr(0) in two steps via a chromium(II) intermediate species. However, this reduction is not quantitative, and the Cr(0) coating is difficult to grow. The destabilization of the [Cr(H 2 O) 6 ] 3+ complex via the addition of an organic complexing agent allows the formation of a reducible Cr(III) complex. The different complexes obtained with the addition of oxalate, formate or acetate were characterized by UV–visible spectroscopy and HPLC-ICP/AES. The nature of the ligand, the [Cr]/[L] ratio and the pH of the solution influence the chemical mechanism of the Cr(III) reduction. Independently of the complex nature, the reduction of Cr(III) to Cr(0) occurs in one step with the three studied complexing agent. Moreover a more quantitative reduction can be obtained by using an organic complexing agent, low [Cr]/[L] ratios and a pH of approximately 3.5. [ABSTRACT FROM AUTHOR]

The effects of feeding sequence of reactants on the properties of a MgAl layered double hydroxide (LDH) coating on Mg alloy are reported herein for the first time. Based on the X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra, MgAl-LDH coatings were successfully obtained with different feeding sequences. However, characterizations of scanning electron microscopy (SEM) and electrochemical methods show that the surface morphologies and corrosion resistance of the MgAl-LDH coatings are dependent upon the feeding sequence. Furthermore, the MgAl-LDH coatings were modified in an 8-quinolinol (8HQ) solution by a facile soaking measurement. Energy dispersive X-ray spectroscopy (EDS) maps and X-ray photoelectron spectroscopy (XPS) spectra demonstrate the effective adsorption of 8HQ layer on the MgAl-LDH primer. The high-resolution N 1s XPS spectra manifest the existence of chemisorption owing to formation of a complex chelate, (bis (8-hydroxyquinolinato) magnesium, Mg(HQ) 2 ), between 8HQ anions and dissolved Mg 2+ . The modified MgAl-LDH coatings, which are named as 8HQ@MgAl-LDH coatings in the body text, show significant enhancement in corrosion resistance and remains excellent corrosion protection even exposure to a NaCl aqueous solution for one month. The mechanism of corrosion inhibition for the 8HQ@MgAl-LDH coatings is proposed finally, which mainly includes the increase in water contact angles, Cl − and CO 3 2− anion-exchangeability, and redeposition of Mg(HQ) 2 precipitation. These findings of this study provide some valuable insights into the corrosion protection mechanism of the MgAl-LDH coatings and the designment of a highly corrosion resistant coating on Mg alloy and other lightweight alloys. [ABSTRACT FROM AUTHOR]

Carbon and aluminum oxide co-coated Na 3 V 2 (PO 4 ) 2 F 3 cathode material has been successfully prepared via a wet chemistry method. The effects of the hybrid layer coating of C and Al 2 O 3 on crystalline structure, morphology and electrochemical performance have been investigated. It is found that C and Al 2 O 3 co-coating can stabilize the structure and improve the conductivity of NVPF. As a cathode material for sodium-ion batteries, the co-coated NVPF electrode shows a significant enhancement in rate capability and cycling performance, i.e., compared with bare NVPF, C-coated NVPF and Al 2 O 3 -coated NVPF, the NVPF/C-Al electrode delivers the highest capacity of 122.8 mAh g −1 with a superior capacity retention ratio of 95.6% after 100 cycles at 1 C. This enhancement in cycling performance and rate capability can be ascribed to the protective effect of this hybrid coating layer of C and Al 2 O 3 on NVPF from electrolyte attack and the facilitated electron/ion transmission caused by the hybrid coating layer. This modification method of co-coating with electronic conductor C and sodium ionic conductivity Al 2 O 3 provides an effective way to improve the electrochemical properties of NVPF and other cathode materials with low electron/ion conductivity for sodium/lithium ion batteries. [ABSTRACT FROM AUTHOR]

LaNiO 3 thin film coated Li-rich cathode Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 material is fabricated for the first time using the facile sol-gel process. Morphology, structure and battery cycle performance of the LaNiO 3 -coated Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 is characterized by a series of tests. LaNiO 3 coating was synthesized by the sol-gel process and uniformly covered powder surface. By coating proper amount of LaNiO 3 , the initial Coulombic efficiency, discharge capacity, rate capability and cycle performance are significantly improved, while the charge transfer resistance reduces. The initial Coulombic efficiency of 3 wt% LaNiO 3 -coating samples reaches the maximum of 70% and 65% at 0.1 C and 1 C rates, respectively. The 3 wt% LaNiO 3 -coating electrode has the highest initial charge/discharge capacity of 405.4/285.1 mAh g −1 at 0.1 C rate (1 C = 250 mA g −1 ), while 5 wt% LaNiO 3 -coating delivers the maximum value of 264.1/165.1 mAh g −1 at 1 C. The cycling performance profiles demonstrate that at 1 C rate, the 3 wt% LaNiO 3 -coated electrode exhibits higher discharge specific capacity of 207.6 mAh g −1 and cyclic stability of 190.3 mAh g −1 92% capacity retention after 50 cycles compared with pristine and other content LaNiO 3 . The film resistance and charge transfer resistance both decrease after coating with LaNiO 3 . LaNiO 3 is an efficient modifier to enhance electrochemical performance of Li-rich cathode materials. [ABSTRACT FROM AUTHOR]

In this work, we propose a novel and delicate strategy to significantly boost the supercapacitive performance of graphite felt (GF)@Co 2 (OH) 2 CO 3 hybrid via a facile Ni−P electrodeposition on the pre-hydrothermally generated GF@Co 2 (OH) 2 CO 3 (denoted as GF@Co 2 (OH) 2 CO 3 @Ni−P). Electrochemical measurements show that the areal specific capacitances of the resulting GF@Ni−P, GF@Co 2 (OH) 2 CO 3 and GF@Co 2 (OH) 2 CO 3 @Ni−P are 118, 1022 and 1360 mF cm −2  at a current density of 1 mA cm −2 . Besides, 72.8% of specific capacitance can be maintained upon rising the current density from 1 to 20 mA cm −2 for GF@Co 2 (OH) 2 CO 3 @Ni−P, far higher than 47.0% for GF@Co 2 (OH) 2 CO 3 . More strikingly, the assembled all-solid-state flexible symmetric supercapacitor GF@Co 2 (OH) 2 CO 3 @Ni−P//KOH//GF@Co 2 (OH) 2 CO 3 @Ni−P delivers high energy densities of 46.8 Wh kg −1  at a power density of 0.5 kW kg −1 , and 20.7 Wh kg −1  at elevated 5.0 kW kg −1 , surpassing most of the reported analogues. Moreover, the device holds 92.9% capacitance retention after 2500 cycles at a current density of 10 mA cm −2 . Such substantially enhanced electrochemical performance of GF@Co 2 (OH) 2 CO 3 @Ni−P owes to the improvement of the electronic conductivity by the Ni−P coating and the reinforced synergic effect contributing to the capacitance between the active Co 2 (OH) 2 CO 3 and Ni species including Ni−P and Ni−OH species. To the best of our knowledge, this is the first report on the coating of Ni−P onto inorganic metal compounds for energy-storage/conversion systems. [ABSTRACT FROM AUTHOR]

Mechanochemically coating over-lithiated layered oxide with the multi-functional VOPO 4 is studied by using that VOPO 4 is capable of accommodating lithium ions that are reversibly inserted/extracted at 3.8 V vs. Li/Li + and exerts a surface-stabilizing effect. The impregnation with VOPO 4 relieves the characteristic irreversible problems of over-lithiated layered oxide, since the initial fully delithiated structure of VOPO 4 provides extra lithium storage sites and thus compensates for the unavoidable loss of irreversible charging capacity of VOPO 4 during the first cycle. Interestingly, VOPO 4 loadings below 1 wt. % improves cycleability, whereas higher loadings result in unfavorable kinetic hindrance. Additionally, VOPO 4 -coated samples exhibit enhanced thermal stability due to featuring reduced decomposition exothermicity and increase thermal runaway onset temperature. [ABSTRACT FROM AUTHOR]

WO 3 -coated Li 1.2 Ni 0.2 Mn 0.6 O 2 cathode materials have been synthesized by using co-precipitation method along with a liquid-evaporation coating process. Investigations via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) reveal that a WO 3 layer is uniformly distributed on the surface of bulk Li 1.2 Ni 0.2 Mn 0.6 O 2 . After coating appropriate amount of WO 3 , the Li-rich cathode materials exhibit improved electrochemical performance. In particular, the 2 wt% WO 3 coated sample (WO 3 -0.02 LLNMO) can deliver an initial discharge capacity of 252.2 mA h g -1 with a low irreversible capacity loss of 44.6 mA h g -1 and remarkable cycling stability of 97% capacity retention after 100 cycles at a current density of 52 mA g −1 . This is mainly due to the effects of the WO 3 coating layer which can suppress the initial activation of Li 2 MnO 3 and improve the stability of surface structure of Li-rich materials by protecting it from corrosion by HF and other side reactions. [ABSTRACT FROM AUTHOR]

The corrosion behavior of electrodeposited binary Fe-Mo and ternary Fe-Mo-P coatings on mild steel substrates as cathodes was investigated in the simulated electrolyte for chlorate production, containing 300 g L −1 of NaCl and 4 g L −1 of K 2 Cr 2 O 7 at 80 °C. Electrochemical noise measurements (ENM), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and scanning reference electrode technique (SRET) were used in this investigation under open circuit potential (OCP) in the simulated shutdown conditions of the chlorate production industry (decay). A filiform corrosion was observed on the surface of all electrodes and in the case of mild steel, a number of pitting sites were also detected. The ternary cathode (Fe 54 Mo 30 P 16 ) containing the highest phosphorous content showed the best resistance to corrosion compared to other coatings and mild steel. Using the ENM technique, a decrease of 67% of the corrosion rate was measured for the Fe 54 Mo 30 P 16 coating compared to Fe 53 Mo 47 after 72 h of decay, whereas mild steel showed 6 times more corrosion compared to the Fe 54 Mo 30 P 16 electrode. The addition of phosphorous to the Fe 53 Mo 47 alloy promoted resistance to corrosion. The corrosion resistance of ternary alloys of Fe-Mo-P were improved with the increase of phosphorous content from 9 to 16 at.%. According to LPR and EIS measurements, the Fe 54 Mo 30 P 16 showed 56%–60% less corrosion compared to the binary Fe 53 Mo 47 electrode. [ABSTRACT FROM AUTHOR]

A simple wet chemical process followed by high temperature calcination has been successfully used to coat Li-ion conductive Li 4 Ti 5 O 12 on the surface of Ni-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 . Physicochemical characterization results indicate that a Li 4 Ti 5 O 12 with a thickness of about 2–3 nm was uniformly distributed on the surface of microspheres, without inducing significant change of the structure and morphology. Electrochemical test results show that proper content of Li 4 Ti 5 O 12 coating layer can greatly improve the cycling performance and rate capability of Ni-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 for the improved Li + ions diffusion rate and suppressed side reactions between electrode and electrolyte. Notably, the 1  wt % Li 4 Ti 5 O 12 coated sample exhibits excellent cycling stability with the capacity retention of 75.86% at 1 C after 170 cycles when cycled between 2.7 and 4.3 V at 25 °C, while that is only 39.40% for bare LiNi 0.8 Co 0.1 Mn 0.1 O 2 . [ABSTRACT FROM AUTHOR]

Ti/IrO 2 -RuO 2 -SiO 2 anodes were prepared using a sol-gel route, followed by thermal decomposition. X-ray diffraction (XRD), field emission-scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM) analysis and voltammetric charges calculation were performed to explore the surface properties of the coating. The electrochemical behavior of the anodes were investigated by cyclic voltammetry (CV), linear sweep voltammogram (LSV), Tafel lines and electrochemical impedance spectroscopy (EIS) measurements. The long-term stability of the anodes were evaluated using accelerated life test (ALT). It indicated that the compositions of the coating are rutile-type IrO 2 , RuO 2 and IrO 2 -RuO 2 solid solution. SiO 2 existed in an amorphous state in the ternary oxide coating. The IrO 2 -RuO 2 -SiO 2 ternary oxide coatings with compact structure and a large amount of acerose crystals of the IrO 2 -RuO 2 solid solution dispersing were detected by FESEM analysis. The generation of the acerose crystals significantly increased the surface area that increased the electrocatalytic activity of the coating. The active surface area of the coating was “outer” active surface dominated. The rate-determining step of the coating for oxygen evolution reaction in sulphuric acid solution can be regarded as the rearrangement of the intermediate. An increase of Ru content can improve the electrocatalytic activity, however, decrease the service lifetime of the anodes. The anode with a molar ratio of Ir:Ru:Si = 9:21:70 is most suitable for OER due to its high electrocatalytic activity, a certain lifetime and low cost. [ABSTRACT FROM AUTHOR]

As a part of understanding of iron and steel passivity, the dissolution rate of magnetite has been studied in anaerobic borate buffer at 25 °C between −0.5 and −0.75 V/SHE. The dissolution rates have been estimated from weight loss measurements. Linear weight losses in time have been obtained corresponding to constant dissolution rates. Nevertheless the rates depended on potential according to a Butler-Volmer law. Another Butler-Volmer law has been obtained for the steady-state cathodic current density flowing through the magnetite layer and ending by the proton reduction step. For both, the quantitative Butler-Volmer parameters have been estimated from the experiments. The cathodic feature of the electrochemical dissolution rate for magnetite was confirmed but the electron balance analysis has shown that this dissolution did not involved electrons as mentioned in the literature. One possible mechanism is proposed in which the kinetics of the proton reduction step tunes the outer voltage drop at the magnetite-solution interface and this voltage drop steers the kinetics of the dissolution rate. [ABSTRACT FROM AUTHOR]

We demonstrate a novel and universal strategy to significantly boost electrochemical performances of conducting polymer-based flexible supercapacitors via the relatively facile electrodeposition of Mo Ni P compounds. The fabricated Mo Ni P@polyaniline (PANI)@carbon fiber cloth (CFC) sandwiched hybrid, for instance, delivers 94.6% of specific capacitance retention from 1 to 40 mA cm −2 and 92.3% of specific capacitance retention at a high current density of 40 mA cm −2 after 2000 cycles, much greater than 56.8% and 58.3% for the uncoated PANI@CFC with Mo Ni P, respectively. With increasing the numbers for repeatedly alternate coating PANI and Mo Ni P layer by layer, the specific capacitances rise almost linearly. Simultaneously, the capacitance retentions maintain high levels at 40 mA cm −2 after 2000 cycles. A remarkable decrease in the charge transfer resistance and a markedly enhanced hydrophilicity with coating Mo Ni P on the surface of PANI@CFC can be found, which can greatly facilitate the electron and electrolyte ion transfer processes and thereby bring with it improved supercapacitive performance. Likewise, the supercapacitive performances of polypyrrole and poly(3,4-ethylenedioxythiophene) can be significantly enhanced in comparison with their Mo Ni P uncoated counterparts. [ABSTRACT FROM AUTHOR]

Lithium rich oxides have over recent years attracted significant attention as materials able to exhibit high electrical capacity, despite, they exhibit poor rate capability and unstable cycling performance. In this paper, layered lithium rich oxide, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 is prepared by solvothermal method and then it is protected by a coating consisting of spinel Li x Mn 1.5 Ni 0.5 O 4 giving rise to a series of spinel/layered heterostructured materials. The results conrfim that the presence of spinel coating offers the 3D pathways for the diffusion of lithium ions and assures long-lasting performances of the resulting cathode materials. In particular the heterostructured materials modified with 2 wt% Li x Mn 1.5 Ni 0.5 O 4 amount exhibits the highest specific capacity (over 264 mAh g −1 at current density of 40 mA g −1 , comparing to 237 mAh g −1 for the pristine layered structured material), excellent initial coulombic efficiency (82%), optimal cycling performance (capacity retention of 94% after 100 cycles at current density of 200 mA g −1 ) and outstanding rate capability with enhanced lithium diffusion coefficient (7.13 × 10 −13 cm −1 s −1 of 2 wt% coating amount is much higher than that of 4.23 × 10 −13 cm −1 s −1 for pristine material electrode). The finding reported in this work provides a novel insight into the design and preparation of high-performance spinel/layered heterostructured materials. [ABSTRACT FROM AUTHOR]

An unprecedentedly high electronic conductivity of 0.27 S cm −1 is achieved by depositing 0.56 wt% crystalline RuO 2 on LNMO via a wet-chemical route. Systematic assessment of the electrochemical performance of bare and RuO 2 -coated LNMO electrodes unambiguously demonstrates that the high electronic conductivity of RuO 2 enables significant enhancement in rate capability. These improvements are dramatic for the electrodes in which extremely low amounts of carbon additives are included and/or the loading amount is high. This finding highlights the importance of electronic conduction in composite electrodes, not only for high power but also for high energy density. The RuO 2 -coated LNMO electrode with 1 wt% carbon additives exhibits a high capacity of 100 mA h g −1 at 1C in the range 3.0–5.0 V (vs. Li/Li + ). This result is in sharp contrast to the negligible capacity exhibited by the bare LNMO electrode. In addition, the chemical/electrochemical stability of the RuO 2 coating under repeated cycling is confirmed, explaining the observed improvement in durability of the RuO 2 -coated LNMO over the bare LNMO. [ABSTRACT FROM AUTHOR]

In this paper, carbon coated Li 5 Cr 9 Ti 4 O 24 is prepared by using cystine as carbon source, which results in the formation of carbon co-doped with nitrogen/sulfur (CNS) coating layer after pyrolysis. Compared with carbon free Li 5 Cr 9 Ti 4 O 24 , the resulting Li 5 Cr 9 Ti 4 O 24 @CNS exhibits enhanced lithium storage capability. Cycled at 500 mA g −1 , it can be found that carbon free Li 5 Cr 9 Ti 4 O 24 can only deliver the reversible capacity of 97.8 mAh g −1 with capacity retention of 80.7% after 200 cycles. In contrast, Li 5 Cr 9 Ti 4 O 24 @CNS can maintain the reversible lithium storage capacity of 111.4 mAh g −1 with capacity retention of 91.9% after 200 cycles. This improvement is attributed to the introduction of nitrogen/sulfur dual-doped carbon coating layer, which significantly enhances the electronic/ionic conductivity and reduces the charge-transfer resistance of Li 5 Cr 9 Ti 4 O 24 . Hence, Li 5 Cr 9 Ti 4 O 24 @CNS may be a promising anode candidate for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Aluminum cobalt oxide-coated LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode materials are synthesized via a wet-coating method. The surface coating of the LNMO with cobalt aluminum oxide (CoAl 2 O 4 ) does not alter its spinel structure, but greatly affects its thermostability. The complete, thin cobalt aluminum oxide coating layer strongly adheres to the host material and possesses a great thermal stability and electrochemical resistance, and it is not damaged in acid or alkali environments. The CoAl 2 O 4 coating layer in this work successfully inhibits the dissolution of transition metal ions and maintain the stability of the LNMO structure. This CoAl 2 O 4 coating layer also hold back the HF scavenger of the spinel structure in the electrolyte, which leads to enhanced electrochemical properties, especially at high temperatures. Furthermore, the coated LNMO exhibits an obviously improved thermostability compared with bare LNMO. [ABSTRACT FROM AUTHOR]

The surface oxidation of TiAlN High Power Pulsed Magnetron Sputtering (HPPMS) hard coatings was investigated using a combined electrochemical and electron spectroscopic approach. The reversible and irreversible surface redox reactions as well as the resulting surface electronic properties were investigated by means of Cyclic Voltammetry (CV) and Electrochemical Impedance Analysis (EIS). X-ray Photoelectron Spectroscopy (XPS) of the TiAlN near-surface region as oxidised in air after deposition revealed a duplex surface film consisting of oxynitridic TiAl(O,N) covered by a shallow Al rich oxide layer. Complementary EIS revealed metallic conductivity of this TiAl(O,N) phase. A detailed microscopic model of the electrochemical oxidation process highlighting the importance of O interstitials for the oxidation process is presented. The electrochemical oxidation induced by CV resulted into a transition from metallic to n-type semiconducting properties of the surface oxide film. As disclosed by XPS and XPS sputter profiling, a complex multi-layered film was formed comprising segregated a-(TiO 2 ) x (Al(OH) 3 ) y located on top of a more ordered electrochemically inactive oxide film. Further, an intermediary nitrogen doped but segregated a-(TiO 2 ) x (Al(OH) 3 ) y :N phase was also observed. The results are of high importance for understanding the electrochemical oxidation and corrosion resistance of these hard coatings. [ABSTRACT FROM AUTHOR]

Zinc oxide wrapped sulphur/carbon nanotubes (ZnO@S/CNT) and nickel hydroxide wrapped sulphur/carbon nanotubes (Ni(OH) 2 @S/CNT) nanocomposites are prepared using a simple, low cost and scalable ball-milling method. As the cathodes in Li-S batteries, the as-prepared ZnO@S/CNT composite illustrates a superior high initial capacity of 1663 mAh g −1 at a charge/discharge rate of 160 mA g −1 , and maintains a reversible capacity at approximately 942 mAh g −1 after 70 cycles. While for Ni(OH) 2 @S/CNT composites, its initial capacity is also as high as 1331 mAh g −1 , but a poorer cycling stability is presented. When the charge/discharge current is increased to 1600 mA g −1 , a high reversible capacity of 698 mAh g −1 after 200 cycles still can be obtained for the ZnO@S/CNT composite, far better than that of Ni(OH) 2 @S/CNT composites. The better cycling performance and high discharge capacity can be attributed to the strong interactions between ZnO and S x 2− species, which is verified by the density functional theory (DFT) calculation result that the ZnO exhibits a higher adsorption energy for Li 2 S 8 than the Ni(OH) 2 . [ABSTRACT FROM AUTHOR]

Conventionally, hydrothermal treatment was often used to modify the TiO 2 surface prior to the growth of hydroxyapatite (HA) that is one of the most important implant biomaterials. In this work, a simple pre-immersion of the obtained TiO 2 in a weak base, instead of the conventionally high pressure-temperature hydrothermal pre-treatment, was conducted prior to the growth of HA. Firstly, anatase TiO 2 coatings with porous surfaces were produced by plasma electrolytic oxidation with optimized processing parameters. X-ray diffraction patterns and field-emission microscopy reveal that the anatase TiO 2 films with porous surfaces were produced by plasma electrolytic oxidation. Subsequently, the films were pre-immersed in 0.1–2 M K 2 HPO 4 solutions for only 10 min. Fourier transform infrared spectroscopy shows that the OH functional groups were generated after such pre-immersion, which could enhance significantly the growth of a single phase of HA in simulated body fluid (SBF). Growth mechanisms of HA via the pre-immersion treatment and soaking in SBF have been proposed. Moreover, the proliferation rate and attachment of the MG-63 osteoblast cells were greatly enhanced on the obtained HA compared to that without the immersion pre-treatment from the MTT assay and morphology analyses. This simple immersion pre-treatment evidently provides an easy route for the growth of HA and has great potential for biomedical applications. [ABSTRACT FROM AUTHOR]

In this work, spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) hollow microspheres are synthesized by an impregnation method using microsphere MnO 2 as both the precursor and template. To enhance the electrical conductivity of LNMO, metal Al was employed for the first time as a coating material for LNMO. Though an Electron-beam Vapor Deposition approach, the surface of LNMO can be easily coated by a tight layer of Al nanoparticles with adjusted thickness. Further annealing the Al-coated sample at 800 °C in air, the Al 3+ -doped LNMO can be obtained. The effects of Al-coating and Al 3+ -doping on the sample morphology and structure are investigated by SEM, TEM, XRD and FT-IR. The electrochemical properties of Al-coated LNMO and Al 3+ -doped LNMO are measured with comparison of bare LNMO by charge/discharge tests and electrochemical impedance spectroscopy (EIS). The results show that both Al-coating and Al 3+ -doping can greatly enhance the cycle performance and rate capability of LNMO. Especially for Al-coated LNMO, it shows the lowest battery impedance due to the existence of conductive Al coating layer, thus delivers the best rate performance among the three. The physical coating procedure used in this work may provide a new facile modification approach for other cathode materials. [ABSTRACT FROM AUTHOR]