Low Electrochemical Performance Research Articles

Isovalent Co-Substitution of Iron and Titanium into Single-Crystal NMC622

Substitutional Li[Ni0.6Mn0.2Co0.2]O2 oxides (known as NMC622) were made by all-dry synthesis with Fe and Ti substituting Co and Mn, respectively. The substitutions were performed in three series, Fe substitution for Co, Ti substitution for Mn, and Fe and Ti co-substitution for Co and Mn, according to the formula Li(Ni0.6Mn0.2−y Co0.2−x Fe x Ti y )O2. The resulting oxides were evaluated as cathode materials for Li-ion batteries. Fe-substitution for Co resulted in increased intersite mixing, resulting in increased polarization and capacity fade. Ti-substitution for Mn also resulted in increased intersite mixing, but the mixing was due to Ti3+ in the Li-layer. As a result, Ti-substituted NMCs had improved capacity retention and reduced polarization. These effects were independent of each other, so that Ti could partially offset the negative aspects of Fe-substitution. Additionally, layered Mn-free Li(Ni0.6Ti0.2Co0.2)O2 (NTC622) was produced as an endmember of this series for the first time with low intersite mixing and superior electrochemical performance in comparison to previous reports. These results demonstrate benefits of all-dry Ti-substitution in NMC and the all-dry synthesis method as an avenue towards new cathode composition discovery.

Exploiting CO2 laser to boost graphite inks electron transfer for fructose biosensing in biological fluids

The possibility to print electronics by means of office tools has remarkedly increased the possibility to design affordable and robust point-of-care/need devices. However, conductive inks suffer from low electrochemical and rheological performances limiting their applicability in biosensors. Herein, a fast CO2 laser approach to activate printed carbon inks towards direct enzymatic bioelectrocatalysis (3rd generation) is proposed and exploited to build biosensors for D-fructose analysis in biological fluids.The CO2 laser treatment was compared with two lab-grade printed transducers fabricated with solvent (SB) and water (WB) based carbon inks. The use of the laser revealed significant morpho-chemical variations on the printed inks and was investigated towards enzymatic direct catalysis, using Fructose dehydrogenase (FDH) integrated into entirely lab-produced biosensors. The laser-driven activation of the inks unveils the inks' direct electron transfer (DET) ability between FDH and the electrode surface. Sub-micromolar limits of detection (SB-ink LOD = 0.47 μM; WB-ink LOD = 0.24 μM) and good linear ranges (SB-ink: 5–100 μM; WB-ink: 1–50 μM) were obtained, together with high selectivity due to use of the enzyme and the low applied overpotential (0.15 V vs. pseudo-Ag/AgCl). The laser-activated biosensors were successfully used for D-fructose determination in complex synthetic and real biological fluids (recoveries: 93–112%; RSD ≤8.0%, n = 3); in addition, the biosensor ability for continuous measurement (1.5h) was also demonstrated simulating physiological D-fructose fluctuations in cerebrospinal fluid.

Experimental and theoretical investigation of silicon-based carbon composite electrode for high performance Li-ion capacitors

Lithium-ion capacitors (LICs) have garnered significant attention in recent years due to their ability to overcome the shortcomings of lithium-ion batteries (LIBs) and supercapacitors (SCs). Silicon (Si) stands out as a superior anode material for LICs due to its compelling attributes, including a high theoretical specific capacity (4200 mAh/g) and a low de-lithiation potential. Nevertheless, the inherent challenges of Si, such as low electrical conductivity and significant volume expansion (300 %), contribute to low electrochemical performance. To address this issue, a conductive carbon layer is introduced on Si using a simple and scalable approach. The resulting architecture, known as carbon-encapsulated Si (Si/C), not only improves electrical properties by enhancing Li+ diffusion but also mitigates volume expansion, leading to enhanced capacity and cyclic stability. Theoretical findings based on density functional theory (DFT) support these enhancements, confirming improved interactive properties at an atomic scale, including low binding energy and accelerated charge transfer kinetics (higher valence charge transfer) between the Si/C electrode and Li ions. As a result, the ‘binder-free’ and flexible Si/C electrode exhibits a notable initial discharge capacity (3450 mAh/g at 0.05 C) with improved rate capability (3010 mAh/g at 0.1 C). When employed as an anode in LICs, the Si/C electrode exhibits outstanding performance, boasting a large energy density (222.29 Wh/kg), high power density (25 kW/kg), and superior cyclic stability (81.3 % over 10,000 cycles). These findings highlight the potential of the Si/C electrode as a formidable candidate for advanced energy storage applications.

A biospecies-derived genomic DNA hybrid gel electrolyte for electrochemical energy storage.

Intrinsic impediments, namely weak mechanical strength, low ionic conductivity, low electrochemical performance, and stability have largely inhibited beyond practical applications of hydrogels in electronic devices and remains as a significant challenge in the scientific world. Here, we report a biospecies-derived genomic DNA hybrid gel electrolyte with many synergistic effects, including robust mechanical properties (mechanical strength and elongation of 6.98 MPa and 997.42%, respectively) and ion migration channels, which consequently demonstrated high ionic conductivity (73.27 mS/cm) and superior electrochemical stability (1.64 V). Notably, when applied to a supercapacitor the hybrid gel-based devices exhibit a specific capacitance of 425 F/g. Furthermore, it maintained rapid charging/discharging with a capacitance retention rate of 93.8% after ∼200,000 cycles while exhibiting a maximum energy density of 35.07 Wh/kg and a maximum power density of 193.9 kW/kg. This represents the best value among the current supercapacitors and can be immediately applied to minicars, solar cells, and LED lightning. The widespread use of DNA gel electrolytes will revolutionize human efforts to industrialize high-performance green energy.

Integrated Textile Supercapacitors Enhanced with Energy‐Absorbing Spacer Fabrics and Ti3C2Tx MXene

AbstractThe rapid development of wearable electronics requires energy storage devices capable of withstanding both static and dynamic deformations. The versatility of textile supercapacitors renders them promising candidates, but their low electrochemical performance especially under mechanical deformation, poses many limitations for practical use. In this study, MXene‐based textile supercapacitors are designed and fabricated using hierarchical spacer fabrics as the skeleton to provide robust mechanical support and stable performance. Ti3C2Tx MXene is adopted as the current collector and active material for the spacer fabric supercapacitor, resulting in an impressive areal capacitance of 415 mF cm−2 with a MXene loading of 4.2 mg cm−2. Remarkable stability and durability are achieved in the form of three‐dimensional (3D) textile supercapacitors, even under both static and dynamic deformations. The compressive behaviors of these supercapacitors can be easily adjusted (e.g., from 10 to 168 KPa at 50% compression) by altering the spacer fabric structure, demonstrating their energy‐absorption (damping of kinetic energy) capability and their potential to meet the requirements of various wearable applications.

Hierarchically porous carbon nanosheets derived from Bougainvillea petals with “pores-on-surface” structure for ultrahigh performance Zinc-ions hybrid capacitors

Due to the outstanding electrochemical performance, high safety coefficient, controllable reaction system and low production cost, Zinc-ion hybrid capacitors (ZIHCs) is considered as a new generation of promising energy storage technology, which even seem as a suitable choice for Medical application. However, to produce ideal carbon-base cathode material with low cost and high electrochemical performance still face challenge. Here, we report a ZIHCs’ cathode based on Bougainvillea petal-derived porous carbon nanosheets (Carbonized Bougainvillea activated at 850 °C, CB-3-850). CB-3-850 derived from Bougainvillea petals exhibit extremely an ultrahigh discharge capacity of 239.1 mAh g−1 at 0.5 A g−1 (from 0 V to 1.8 V) and an excellent electrochemical stability at 20 A g−1 (90 %, 10,000 cycles). In addition, ultrahigh energy density (213.4 Wh kg−1) and high power density (14.8 kW kg−1) are realized in CB-3-850. Special “pores-on-surface” structure and ultrathin nanosheet-like morphology of CB-3-850 not only provide a high specific surface area that for more Zn2+ and SO42+ absorbed on its surface but also enable ions across the one nanosheet directly to reach other carbon-sheets units, which realize a fast kinetic process of ions storage and higher capacity. The excellent performance of the Zinc-ion capacitor can be also attributed to N and O doping that strongly interacted with Zn2+ during the charge/discharge process. Finally, natural Bougainvillea petal just contains simple non-metal elements like C, N and O, exhibit high biocompatibility.

Bio-based anode material production for lithium–ion batteries through catalytic graphitization of biochar: the deployment of hybrid catalysts

Producing sustainable anode materials for lithium-ion batteries (LIBs) through catalytic graphitization of renewable biomass has gained significant attention. However, the technology is in its early stages due to the bio-graphite's comparatively low electrochemical performance in LIBs. This study aims to develop a process for producing LIB anode materials using a hybrid catalyst to enhance battery performance, along with readily available market biochar as the raw material. Results indicate that a trimetallic hybrid catalyst (Ni, Fe, and Mn in a 1:1:1 ratio) is superior to single or bimetallic catalysts in converting biochar to bio-graphite. The bio-graphite produced under this catalyst exhibits an 89.28% degree of graphitization and a 73.95% conversion rate. High-resolution transmission electron microscopy (HRTEM) reveals the dissolution–precipitation mechanism involved in catalytic graphitization. Electrochemical performance evaluation showed that the trimetallic hybrid catalyst yielded bio-graphite with better electrochemical performances than those obtained through single or bimetallic hybrid catalysts, including a good reversible capacity of about 293 mAh g−1 at a current density of 20 mA/g and a stable cycle performance with a capacity retention of over 98% after 100 cycles. This study proves the synergistic efficacy of different metals in catalytic graphitization, impacting both graphite crystalline structure and electrochemical performance.

An industrial mixed rare-earth oxide fuel cell with low cost and high electrochemical performance

Rare-earth oxides determine the commercialization and development of solid oxide fuel cells (SOFCs) for all the types, still remining challenges of high cost and low electrochemical performance. Here, we propose an industrial mixed rare-earth oxide fuel cell using the state-of-the-art industrial lanthanum-praseodymium-cerium (La-Pr-Ce, LCP) oxide electrolyte as a proof-of-concept, achieving low-cost and high electrochemical performance. The rare-earth oxides, La2O3, CeO2, PrO2 and LCP are prepared and studied by oversimplified solid reaction experiments with density functional theory (DFT) calculations. The LCP is simplified as La, Pr doped CeO2, in which the effects of rare-earth elements doping are concluded as follows: firstly, the Ce4+/Ce3+ redox pairs can be slightly suppressed by La, Pr co-doping; secondly, the bandgap of LCP is decreased to 2.01 eV with enhanced electron conductivity of 7.4 × 10−5 S cm−1, which may originate from Pr-doping. The power density output of industrial mixed rare-earth oxide fuel cells with La2O3, CeO2, PrO2 and LCP electrolytes achieve 630 mW cm−2, 639 mW cm−2, 469 mW cm−2 and 797 mW cm−2 at 500 °C, respectively, indicating that the LCP electrolyte presents ascendant performance output with the ionic conductivity of 0.248 S cm−1. The industrial mixed rare-earth oxide fuel cells not only broaden the exploit avenue for industrial mixed rare-earth oxides, but also unravel the roadblock for the industrialization of SOFCs at low temperatures below 500 °C.

Exploring Battery Materials for Ca Batteries

Rechargeable calcium (Ca) batteries have the prospects of high energy, low-cost and sustainability. Ca metal has a low reduction potential of -2.9 V vs. NHE (close to that of lithium -3.0 V)) and a high capacity, and thus the voltage and energy density of Ca batteries is potentially comparable with lithium-ion batteries. However, divalent Ca-ions and reactive Ca metal strongly interact with cathode materials and electrolyte solutions, leading to high charge-transfer barriers at the electrode-electrolyte interfaces and consequently low electrochemical performance. Herein, we will present the recent progress in the development of stable calcium tetrakis(hexafluoroisopropyloxy) borate Ca[B(hfip)4]2 (hfip = CH(CF3)2) electrolytes and the search for suitable cathode materials. We will discuss the interfacial properties of Ca anodes in liquid electrolytes and the chemistry of sulfur conversion electrodes in Ca batteries. References Li, O. Fuhr, M. Fichtner, Z. Zhao-Karger, Towards stable and efficient electrolytes for room-temperature rechargeable calcium batteries.Energy Environ. Sci. 12, 3496 (2019).Li, Z. M. Fichtner, Z. Zhao-Karger, Rechargeable Calcium–Sulfur Batteries Enabled by an Efficient Borate-Based Electrolyte. Small 16, 1–6 (2020).Zhao-Karger, Y. Xiu, Z. Li, A. Reupert, T. Smok, M. Fichtner, Calcium-tin alloys as anodes for rechargeable non-aqueous calcium-ion batteries at room temperature, Nature Comm. 13, 3849 (2022).

The Effect of Conductive Additive Morphology and Crystallinity on the Electrochemical Performance of Ni-Rich Cathodes for Sulfide All-Solid-State Lithium-Ion Batteries

Sulfide electrolyte all-solid-state lithium-ion batteries (ASSLBs) that have inherently nonflammable properties have improved greatly over the past decade. However, determining both the stable and functional electrode components to pair with these solid electrolytes requires significant investigation. Solid electrolyte comprises 20–40% of the composite cathode electrode, which improves the ionic conductivity. However, this results in thick electrolyte that blocks the electron pathways in the electrode, significantly lowering the electrochemical performance. The application of conductive carbon material is required to overcome this issue, and, hence, determining the carbon properties that result in the most stable performance in the sulfide solid electrolyte is vital. This study analyzes the effect of the cathode conductive additive’s morphology on the electrochemical performance of sulfide electrolyte-based ASSLBs. Carbon black (CB) and carbon nanotubes (CNTs), which provide electron pathways at the nanoscale and sub-micron scale, and carbon nanofiber (CNF), which provides electron pathways at the tens-of-microns scale, are all tested individually as potential conductive additives. When the CNF, with its high crystallinity, is used as a conductive material, the electrochemical performance shows an excellent initial discharge capacity of 191.78 mAh/g and a 50-cycle capacity retention of 83.9%. Conversely, the CB and the CNTs, with their shorter pathways and significantly increased surface area, show a relatively low electrochemical performance. By using the CNF to provide excellent electrical conductivity to the electrode, the polarization is suppressed. Furthermore, the interfacial impedance across the charge transfer region is also reduced over 50 cycles compared with the CB and CNT composite cells. These findings stringently analyze and emphasize the importance of the morphology of the carbon conductive additives in the ASSLB cathode electrodes, with improvements in the electrochemical performance being realized through the application of long-form two-dimensional crystalline CNFs.

2D Germanane‐MXene Heterostructures for Cations Intercalation in Energy Storage Applications

AbstractHeterostructures offer an exceptional possibility of combining individual 2D materials into a new material having altered properties compared to the parent materials. Germanane (GeH) is a 2D material with many favorable properties for energy storage and catalysis, however, its performance is hindered by its low electrical conductivity. To address the low electrochemical performance of GeH, a heterostructure of GeH and Ti3C2Tx is fabricated. The Ti3C2TX is a layered material belonging to the family of MXenes. The resulting heterostructure (GeMXene) at a defined mass ratio of GeH and Ti3C2Tx shows superior capacitive performance that surpasses that of both pristine materials. The effect of the size of cations and anions for intercalation into GeMXene in different aqueous salt solutions is studied. GeMXene allows only cation intercalation, which is evidenced by the gravimetric electrochemical quartz crystal microbalance (EQCM) technique. The capacitive performance of the GeMXene is compared in neutral, acidic, and alkaline electrolytes to determine the best electrochemical performance. This unleashes the potential use of GeMXene heterostructure in different electrolytes for supercapacitors and batteries. This work will pave the way to explore the heterostructures of other 2D materials such as novel MXenes and functionalized germanane for highly energy‐storage efficient systems, and beyond.

Monovalent ion doping to enhance the performance of cobalt-free Sm0.5Sr0.5FeO3-δ cathode for YSZ fuel cells

Solid oxide fuel cells (SOFCs) are energy conversion devices that can solve the energy crisis and environmental pollution, but the low electrochemical performance at intermediate temperatures is still an urgent problem to be addressed. In this work, we investigate the effect of K and F doping on the performance of conventional cobalt-free cathode SSF. XRD demonstrates that SSF, SSKF, SSFF, and SSKFF each display a cubic perovskite structure. Additionally, HT-XRD reveals that SSF, SSKF, and SSFF exhibit exceptional thermal stability, while SSKFF produces the impurity phase Sr3Fe2O7 during the test. XPS suggests that the improvement in SSF performance, resulting from F and K doping, can be largely attributed to the increase in adsorbed oxygen content, which enhances the ORR catalytic activity. The O2-TPD outcomes indicate that F and K doping stimulate the formation of oxygen vacancies at higher temperatures, thus promoting ORR catalytic activity. Experimentally, the electrochemical impedance spectra results indicate that both K and F doping led to a reduction in the value of polarization resistance, which decreased by over 20% at 800 °C. Regarding the output performance, both K and F doping resulted in a substantial increase in the output power from 670.05 to 825.88 and 796.76 mW·cm−2 respectively, at 800 °C. However, co-doping with F and K led to a notable reduction in polarization impedance and output power, possibly due to the formation of heterogeneous phases during testing. The results indicate that enhancing the electrochemical performance of SSF can be achieved through the doping of K cations and F anions, but co-doping leads to a decreased performance.

Engineering Lung-Inspired Flow Field Geometries for Redox Flow Batteries with Stereolithography 3D Printing

Redox flow batteries are a promising electrochemical technology for low-cost, scalable and long-duration energy storage, but their energy market penetration is hampered by elevated costs1,2. One effective strategy is to increase the overall efficiency of the electrochemical stack. At the core of the electrochemical cells, the design of the flow fields—which distribute the electrolyte through the porous electrodes—determines, in combination with the electrode microstructure, the performance of the system3. To date, current designs are inspired on fuel cell technologies but have not been engineered for redox flow cells where single-phase reactive flows are sustained4.In this work, we tailor lung-inspired flow field geometries for carbon paper electrodes using stereolithography 3D printing5,6. We propose two new lung-inspired geometries—with two and three channel levels—and compare them to a baseline interdigitated flow field. A two-step process based on stereolithography 3D printing followed by the application of a conductive coating is used to manufacture these complex flow field geometries. We employ a suite of electrochemical (i.e., polarization and electrochemical impedance spectroscopy) and fluid dynamic (pressure drop measurement) techniques together with numerical modelling to elucidate flow architecture-performance relationships. We find that lung-inspired structural patterns homogenize the electrolyte distribution into the electrode, accessing a larger electrode reaction area. These fractal geometries can outperform traditional interdigitated flow fields, providing a more favourable balance between low pressure drop and high electrochemical performance (Figure 1). In this talk, I aim to leverage lung-inspired flow field geometries as a promising prospect for engineering advanced flow cell architectures for emerging electrochemical devices. References 1 E. Sánchez-Díez, J. Power Sources, 2021, 23.2 L. F. Arenas, C. Ponce de León and F. C. Walsh, J. Energy Storage, 2017, 11, 119–153.3 R. M. Darling and M. L. Perry, J. Electrochem. Soc., 2014, 161, A1381–A1387.4 C. R. Dennison, E. Agar, B. Akuzum and E. C. Kumbur, J. Electrochem. Soc., 2016, 163, A5163–A5169.5 J. Marschewski, L. Brenner, N. Ebejer, P. Ruch, B. Michel and D. Poulikakos, Energy Env. Sci, 2017, 10, 780–787.6 M. P. Browne, E. Redondo and M. Pumera, Chem. Rev., 2020, 120, 2783–2810. Figure 1

Sulfurized poly(o-phenylenediamine) as a novel high-performance solid-phase conversion sulfur cathode

The combination of sulfurized polymer cathode and ester-type electrolyte can realize the solid-phase conversion of sulfur cathode, which is a promising solution of the dissolution issue of Li–S batteries. In this regard, sulfurized polyacrylonitrile (SPAN) is the most famous material and few attempts have been made to challenge it in the past two decades. Herein, we report sulfurized poly(o-phenylenediamine) (SPoPDA) as its supplement or alternative for rechargeable lithium batteries. Compared with SPAN, SPoPDA shows higher ability to covalently bond with sulfur (from ∼50 to ∼60 wt%), similar reversible capacity (∼600 mAh g−1), better cycling stability (with only 2% loss of charge capacity during 100 cycles), and faster reaction kinetics. The molecular structures and electrochemical reaction mechanisms of them have been quantitatively analyzed, and the electrode structure variation of SPoPDA during discharge–charge process has been thoroughly investigated. This work provides not only a novel sulfurized polymer cathode material with low cost, easy synthesis, and high electrochemical performance, but also clearer mechanism understanding of solid-phase conversion sulfur cathode, which are of significant importance for the development of Li–S batteries towards practical application.

NTO laminated graphite felt as high-performance negative electrode for vanadium redox flow batteries

In recent years, vanadium redox flow batteries (VRFBs) have attracted global interests owing to their advantages of large scale, high safety and long-term cyclability. Nevertheless, the unsatisfactory kinetics of carbon-based anodes limits the commercial application of VRFBs. Especially, graphite felt (GF) as a representative anode material, has critical disadvantage of poor electrolyte wettability due to its hydrophobic surface. This limitation of interfacial properties between the electrode and electrolyte causes inefficient charge transportation, which leads to low electrochemical performance with poor cycle stability. To improve the surface properties of GF anodes for VRFB, we introduce a lamination layer of Nb-doped TiO2 (NTO) to a heat-treated graphite felt (HGF) via ultrasonic spray pyrolysis deposition. The NTO laminated HGF offers hydrophilic surface with several advantages of high catalytic activity, high electrical conductivity, and high specific surface area. As an anode material, the hybrid structure of the NTO lamination layer on the HGF demonstrates synergistic effects, thus enabling superior energy storage performance compared with other electrodes. Especially, the NTO-HGF anode shows an energy efficiency of 82.03%, which is 6.2% higher than that of pristine GF. We demonstrate that the introduction of an NTO lamination layer can be a prospective candidate for improving the VRFB anodes performance.

An ultrafast rechargeable and high durability lithium metal battery using composite electrolyte with the three-dimensional inorganic framework by Li6.4La3Zr1.4Ta0.6O12 surface functionalization

The liquid electrolyte used in traditional lithium-ion batteries has risks of leakage, combustion and explosion. Solid electrolyte is one of the effective strategies to solve the safety problems of lithium-ion batteries. And the use of solid electrolytes makes it possible to use lithium metal as an anode to achieve higher energy densities. At present, the main factors restricting the performance improvement of all-solid-state lithium batteries are the low electrochemical performance of electrolytes and poor solid-solid interface contact. The composite electrolyte has the advantages of both inorganic materials and polymers, but its electrochemical performance is still not up to the requirements of use. In situ synthesis of LaRuO3 with perovskite structure on the surface of Li6.4La3Zr1.4Ta0.6O12(LLZTO) induces the formation of Li2Zr2O7 while introducing defects. The Li2Zr2O7 phase "welds" inorganic particles into three-dimensional(3D) inorganic framework, increasing the reaction sites between inorganic fillers and polymers. Compared with the primitive sample, the ionic conductivity of the modified electrolyte is increased by an order of magnitude at room temperature, wherein the lithium-ion conductivity of the composite electrolyte with 3% LaRuO3 is as high as 6.06 × 10−4 S cm−1. At 5C, the discharge specific capacity of LiFePO4 | [email protected] 3% LRO | Li can reach 114.6 mAh g−1; After 400 cycles, the discharge specific capacity remains at 129.6 mAh g−1. Under the same conditions, the discharge specific capacities of the unmodified samples are only 92.4 mAh g−1 and 35 mAh g−1. The high rate discharge performance of solid-state lithium metal battery supports the high torque output of motor, which improves the acceleration performance of electric vehicles or ships. The high capacity and excellent cycle performance of solid-state lithium metal battery can significantly extend the driving range and service life of electric vehicles.

Octahedral V2O5 derived Au-decorated disordered rock salt as high-rate and long-life anode materials for Lithium-ion storage

V2O5 is a kind of promising electrode material in Li-ion batteries because of its low cost, high specific capacity, and abundant resources, and it can convert into several LixV2O5 phases during the initial Li-insertion progress. Depending on the electrochemical activity of V2O5 at a low voltage region, a disordered rock salt (LixV2O5) anode is synthesized by the electrochemical in-situ methods. Nevertheless, the low electronic conductivity and electrochemical performance limit its utilization. Herein, Au is employed as an additive to enhance the Li-storage performance of LixV2O5. The electrochemical performances of V2O5 and V2O5/Au composites are systematically investigated; compared with V2O5, V2O5/Au composite possesses excellent initial discharging and charging capacities of 2, 572.8/395.6 mAh g−1, and after 4, 000 cycles, a reversible discharging and charging specific capacity of 229.8/229.5 mAh g−1 could be remained at the current density of 0.5 A g−1. More interestingly, V2O5/Au composite shows a high-rate capacity of 114.7 mAh g−1 even at 5.0 A g−1 after 10, 000 cycles. The electrode kinetic studies demonstrate that Au can enhance the electronic conductivity of V2O5, the initial discharging and CV curves reveal the phase inversion mechanisms of V2O5/Au composites during initial discharging progress. These data provide a fire-new method to enhance the electrochemical properties of LixV2O5.

Nanowires-Assembled TiO2 Nanorods Anchored on Multilayer Graphene for High-Performance Anodes of Lithium-Ion Batteries.

Multilayer graphene (MLG) prepared via ultrasonic exfoliation has many advantages such as its low-cost and defect-free nature, high electronic conductivity, and large specific surface area, which make it an apt conductive substrate for TiO2 composites. To synthesize graphene/TiO2 hybrids, traditional methods that greatly depend on the chemical bond of oxygen-containing functional groups on graphene with titanium cations are not applicable due to the absence of these functional groups on MLG. In this work, a facile chemical method is developed to directly deposit TiO2 on the MLG surface without the introduction of chemically active groups. With this method, four types of TiO2 materials, that is pure anatase TiO2 nanoparticles, a mixture of anatase TiO2 nanoparticles and rutile TiO2 nanoflowers, pure rutile TiO2 nanoflowers, and pure rutile TiO2 nanorods, are homogeneously anchored on the MLG surface by controlling the amount of HCl in the reactant. Interestingly, the rutile TiO2 nanorods in the TiO2/MLG composite are assembled by many TiO2 nanowires with an ultra-small diameter and ultra-long length, which provides a better synergetic effect for high performances as LIB anodes than other composites. A specific capacity of 631.4 mAh g−1 after 100 cycles at a current density of 100 mA g−1 is delivered, indicating it to be a valuable LIB anode material with low cost and high electrochemical performances.

Dual-Use of Seawater Batteries for Energy Storage and Water Desalination.

Seawater batteries are unique energy storage systems for sustainable renewable energy storage by directly utilizing seawater as a source for converting electrical energy and chemical energy. This technology is a sustainable and cost-effective alternative to lithium-ion batteries, benefitting from seawater-abundant sodium as the charge-transfer ions. Research has significantly improved and revised the performance of this type of battery over the last few years. However, fundamental limitations of the technology remain to be overcome in future studies to make this method even more viable. Disadvantages include degradation of the anode materials or limited membrane stability in aqueous saltwater resulting in low electrochemical performance and low Coulombic efficiency. The use of seawater batteries exceeds the application for energy storage. The electrochemical immobilization of ions intrinsic to the operation of seawater batteries is also an effective mechanism for direct seawater desalination. The high charge/discharge efficiency and energy recovery make seawater batteries an attractive water remediation technology. Here, the seawater battery components and the parameters used to evaluate their energy storage and water desalination performances are reviewed. Approaches to overcoming stability issues and low voltage efficiency are also introduced. Finally, an overview of potential applications, particularly in desalination technology, is provided.

Electrochemical performance of MoO3-RuO2/Ti in H2SO4 electrolyte as anodes for asymmetric supercapacitors

Based on the corrosion and low decomposition voltage of acid solutions, many electrodes are limited in the fields of supercapacitors. MoO3 has a wide potential window from -1.0 to 0.8 V in acid solution in theory. But there are very few reports of MoO3 used as anode due to its poor cycle stability and low electrochemical performance under a negative potential in most electrolyte solutions. The MoO3-RuO2/Ti was prepared by thermal decomposition. The phase structure, pore size, microstructure and capacitive characteristics of the MoO3-RuO2/Ti with different content of RuO2 were analyzed in detail by XRD, SEM, EDS, XPS, BET and electrochemical tests. The amorphous RuO2 was evenly distributed in MoO3. Remarkably, a high surface area and total pore volume were achieved by adding 5mol% RuO2 into MoO3, which resulted in a specific capacity of 639 C g–1 at 1A g–1. The poor cycle stability and electrochemical performance of MoO3 under a negative potential were greatly improved by adding RuO2. MoO3-RuO2/Ti used as anode in H2SO4 electrolyte was firstly discussed. The working voltage of MoO3-RuO2/Ti for anode was -0.35 to 0 V and had an excellent specific electrochemical performance. Asymmetric supercapacitor (ASC) was constructed using the MoO3-RuO2/Ti as anode and the IrO2-ZnO/Ti as cathode in H2SO4 electrolyte, which could be run under the potential range from 0 to 1.5 V. When the power density of asymmetric supercapacitor was 932 W kg–1 and 6580 W kg–1, the energy density was 80.5 Wh kg–1 and 57.4 Wh kg–1, respectively. Asymmetric supercapacitor with the MoO3-RuO2/Ti as anode and the RuO2-ZnO/Ti as cathode was also successfully assembled.