Mass Loading Levels Research Articles

Ti─O─C Bonding at 2D Heterointerfaces of 3D Composites for Fast Sodium Ion Storage at High Mass Loading Level.

3D composite electrodes have shown extraordinary promise as high mass loading electrode materials for sodium ion batteries (SIBs). However, they usually show poor rate performance due to the sluggish Na+ kinetics at the heterointerfaces of the composites. Here, a 3D MXene-reduced holey graphene oxide (MXene-RHGO) composite electrode with Ti─O─C bonding at 2D heterointerfaces of MXene and RHGO is developed. Density functional theory (DFT) calculations reveal the built-in electric fields (BIEFs) are enhanced by the formation of bridged interfacial Ti─O─C bonding, that lead to not only faster diffusion of Na+ at the heterointerfaces but also faster adsorption and migration of Na+ on the MXene surfaces. As a result, the 3D composite electrodes show impressive properties for fast Na+ storage. Under high current density of 10mAcm-2, the 3D MXene-RHGO composite electrodes with high mass loading of 10mgcm-2 achieve a strikingly high and stable areal capacity of 3mAhcm-2, which is same as commercial LIBs and greatly exceeds that of most reported SIBs electrode materials. The work shows that rationally designed bonding at the heterointerfaces represents an effective strategy for promoting high mass loading 3D composites electrode materials forward toward practical SIBs applications.

Enhanced synergistic effect of NiCo sulfide nanorod arrays with high mass loading on carbon cloth for hybrid supercapacitors: The role of compositional regulation

Achieving an enhanced synergistic effect and controlling the morphology of active materials to facilitate electrolyte access are crucial for the design of high-mass-loading electrode. In this work, NiCo sulfide nanorod arrays were grown on a carbon cloth (CC) substrate via a two-step hydrothermal deposition strategy. The compositional effect was employed to modify the growth behavior, hierarchical morphology, and synergistic effect of the as-obtained electrodes. The contents of Ni-S and Co-S species and the resistance nature of the electrodes can be optimized by adjusting the Co/Ni feed ratio. The optimized Ni1.5Co1.5S4/CC electrode with a high mass loading (5.54 mg cm−2) comprises vertical nanorod arrays with open channels for electrolyte access, and exhibits a high capacity of 711 C g−1 at 2 A g−1 (3.95 C cm−2 at 10 mA cm−2) with good cyclic stability. The as-assembled Ni1.5Co1.5S4/CC//activated carbon cloth (ACC) hybrid supercapacitor delivers a high areal capacity of 1.96 C cm−2 at 5 mA cm−2 with excellent rate performance and achieves a high energy density of 0.49 mWh cm−2 at a power density of 4.5 mW cm−2. These achievements represent a promising concept for the practical design and regulation of NiCo sulfide electrodes at high mass loading levels.

Boosting the Sodium-Ion Transport and Surface Pseudocapacitance of a SnO2 Nanoflower at a High Mass Loading Level for High Areal Capacity and Fast Sodium-Ion Storage

Boosting the Sodium-Ion Transport and Surface Pseudocapacitance of a SnO₂ Nanoflower at a High Mass Loading Level for High Areal Capacity and Fast Sodium-Ion Storage

Holey Graphene/Ferroelectric/Sulfur Composite Cathodes for High-Capacity Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have attracted considerable interest as next-generation high-density energy storage devices. However, their practical applications are limited by rapid capacity fading when cycling cells with high mass loading levels. This could be largely attributed to the inferior electron/ion conduction and the severe shuttling effect of soluble polysulfide species. To address these issues, composites of sulfur/ferroelectric nanoparticles/ho ley graphene (S/FNPs/hG) cathodes were fabricated for high-mass-loading S cathodes. The solvent-free and binder-free procedure is enabled using holey graphene as a unique dry-pressable electrode for Li-S batteries. The unique structure of the holey graphene framework ensures fast electron and ion transport within the electrode and affords enough space to mitigate the electrode's volume expansion. Moreover, ferroelectric polarization due to FNPs within S/hG composites induces an internal electric field, which effectively reduces the undesired shuttling effect. With these advantages, the S/FNPs/hG composite cathodes exhibit sustainable and ultrahigh specific capacity up to 1409 mAh/gs for the S/BTO/hG cathode. A capacity retention value of 90% was obtained for the S/BNTFN/hG battery up to cycle 18. The high mass loading of sulfur ranging from 5.72 to 7.01 mgs/cm2 allows maximum high areal capacity up to ∼10 mAh/cm2 for the S/BTO/hG battery and superior rate capability at 0.2 and 0.5 mA/cm2. These results suggest sustainable and high-yielding Li-S batteries can be obtained for potential commercial applications.

High Mass Loading 3D‐Printed Sodium‐Ion Hybrid Capacitors

AbstractSodium‐ion hybrid capacitors (SIHCs) have been regarded as one of the promising energy devices thanks to its low cost and compromise between energy density and power density, yet remain a challenge towards practical levels of mass loading (>10 mg cm−2). Herein, the fabrication of a 1D core–shell structure is reported with N‐doped porous carbon encapsulating ZnV2O4 nanofibers (ZnV2O4NFs@N‐PC), which features an open framework and favorable properties for facilitating ion diffusion, mass transportation, and electron transfer, enabling it to perform impressively for sodium ions storage. A 3D printed SIHC is conceptually proposed by coupling the 3D printed ZnV2O4NFs@N‐PC anode with a 3D printed active carbon cathode, which can deliver a high energy/power density of 145.07 Wh kg−1/3677.1 W kg−1 with a durable cycling lifespan. It is demonstrated that the 3D printed SIHC, even at a high mass loading of up to 16.25 mg cm−2, can release a high areal energy/power density of 1.67 mWh cm−2/38.96 mW cm−2, outperforming most of the SIHCs developed so far. The present work sheds light on the role of the design of electrode materials and verifies the promise of 3D‐printed technology for next‐generation electrochemical energy devices.

Effects of In Situ Remediation on Copper Distribution and Soil Aggregate Adsorption–Desorption Characteristics in Smelter-Impacted Soil

To evaluate the effect of in situ chemical remediation on copper (Cu) immobilisation and migration, in situ chemically remediated soils from a smelter-impacted field were partitioned into four aggregate size fractions and their Cu adsorption characteristics were investigated. The results indicate that the highest Cu concentration occurred in the <0.053 mm size fraction, while the highest Cu mass loading was obtained in the 0.25–2 mm size fraction (39.9–42.5%). However, in situ remediation increased the Cu mass loading levels in the >0.25 mm aggregates. A pseudo-second-order model was used to fit the adsorption process obtained in kinetic experiments, while the data from isothermal experiments were described using the Freundlich model. The fastest adsorption rate was observed in the <0.053 mm fraction, and the adsorption capacity of the soil aggregates improved after combined in situ remediation. The amount of Cu2+ adsorbed increased with increasing pH. The <0.053 mm fraction exhibited lower desorption compared with the other fractions at low pH values. In addition, all particle size aggregates treated with apatite and Elsholtzia splendens had the lowest desorption rates at different pH values.

Strong anti-stacking structure formation in graphene materials obtained by chemical liquid deposition

The porous graphene derived from the chemical liquid deposition (CLD) methodology using waste tire pyrolysis oil (WTPO) as carbon precursor possesses the hexagon-like microarchitecture decorated with abundant mesoporous structure, good non-stacking property and excellent amphipathic property. The developed technique provides the strong anti-stacking behavior to graphene as compared to the conventional chemical vapor deposition (CVD). The outstanding lubricating function of WTPO and strong London dispersion force between WTPO and MgO catalyst, devotes to forming the few-layered graphene with non-stacking state. As the electrode for symmetric supercapacitors, CLD-derived graphene (CLDG) not only possesses superior capacitive storage ability over those of graphene derived from CVD and commercial activated carbon under aqueous and organic electrolyte systems, but also presents excellent compatibility to gravimetric and areal capacitances even under the commercial mass loading level (10 mg cm−2). Besides, Li ion capacitor assembled with CLDG as cathode and anode delivers the satisfactory Ragone performance and ultralong cycle life. Because of the outstanding non-stacking feature and well-developed pore channels, the overall interface of CLDG electrode can be sufficiently accessed by electrolyte ions, contributing to its exceptional capacitive behavior. This work provides a feasible strategy to produce non-stacking porous graphene with high quality in terms of good monodispersion and large specific surface area via the high value-added utilization of WTPO.

High-volumetric capacitance and high-rate performance in liquid-mediated densified holey MXene film

Achieving both high-volumetric capacitance and high-rate performance in thick pseudocapacitive film materials plays a critical role in facilitating the realization of large-scale electrochemical energy storage. However, MXene (Ti3C2Tx), as a two-dimensional material with a high aspect ratio, is blocked by the industry problem of nanosheets self-stacking when assembled into dense films, which would induce extremely poor ionic mobility and significant attenuation of thick electrode performance. Herein, we create uniform in-plane nanopore defects in MXene nanosheets, and introduce nonvolatile liquids with different water contents, in which the interlaminar structure of holey MXene film can be accurately controlled by the capillary compression generated during evaporation. More importantly, the residual nonvolatile liquids effectively maintain the wettability of MXene surface, making it is easy to obtain compact pseudocapacitive film materials with pore structure connectivity, and allows ions to rapidly transport. The results demonstrate that the liquid-mediated densified holey MXene film can still present high-volumetric capacitance and high-rate performance at the actual mass loading level (>10 mg cm−2), which is of great significance for promoting the advancement of MXene materials from the theoretical elucidation to practical application.

Analysis of the Effect of Particle Shape on Pore Structure

Market requirements for lithium-ion batteries are gradually increasing as they expand their applications from small electronic devices to large EVs and ESSs. Various active materials, binders, and conductive materials could be used to make batteries. In manufacturing electrodes, the microstructure of each porous electrode will vary depending on the size and shape of the particles used.1 Many studies show that the microstructure of lithium-ion battery electrodes affects cell resistance, cycle life, and rate capabilities.In this study, electrodes with various mass loading levels and composite densities were fabricated using single crystal and secondary particle NCM cathode active materials. Two major parameters of the porous electrode, porosity and tortuosity, were obtained. Mercury intrusion porosimetry was used to measure porosity. Tortuosity was obtained from Bruggeman’s relationship,2,3 using electrochemical impedance spectroscopy (EIS). We compared porosity and tortuosity values with the SEM image of each electrode. It was confirmed that the pore structure can be well maintained in the single crystal NCM based electrode due to the high stiffness of the active material.References Harris, Stephen J., and Peng Lu. The Journal of Physical Chemistry C 13 (2013): 6481-6492.Landesfeind, Johannes, et al. Journal of The Electrochemical Society 7 (2016): A1373-A1387.Bruggeman, Von DAG. Annalen der physic 7 (1935): 636-664.

Average cometary ion flow pattern in the vicinity of comet 67P from moment data

ABSTRACT Average flow patterns of ions around comet 67P detected by the RPC-ICA instrument onboard Rosetta are presented both as a time series and as a spatial distribution of the average flow in the plane perpendicular to the comet – Sun direction (Y–Z plane in the coordinate systems used). Cometary ions in the energy range up to 60 eV flow radially away from the nucleus in the Y–Z plane, irrespective of the direction of the magnetic field, throughout the mission. These ions may however be strongly affected by the spacecraft potential, the uncertainty due to this is briefly discussed. Inside the solar wind ion cavity and in the periods just before and after, the cometary pick up ions moving antisunward are deflected against the inferred solar wind electric field direction. This is opposite to what is observed for lower levels of mass-loading. These pick up ions are behaving in a similar way to the solar wind ions and are deflected due to mass-loading. A spatial asymmetry can be seen in the observations of deflected pick up ions, with motion against the electric field primarily within a radius of 200 km of the nucleus and also in the negative electric field hemisphere. Cometary ions observed by RPC-ICA typically move in the antisunward direction throughout the mission. These are average patterns, full-resolution data show very much variability.

Three-Dimensional SiC/Holey-Graphene/Holey-MnO2 Architectures for Flexible Energy Storage with Superior Power and Energy Densities.

Although nanostructured materials have recently enabled a dramatic improvement of the current energy-storage units in portable electronics with enhanced functionality, it is still challenging to provide a cost-efficient solution to attain the ultrahigh energy and power densities of supercapacitors (SCs) since nearly arbitrary electrodes are limited to the thinner porous structure with de facto rather low mass loading (∼1 mg cm-2) because of the huge limitations of pronounced impaired ion transport in subnanometer pores in thicker compact electrodes. In this contribution, we report the fabrication of a macro/mesoporous hybrid hierarchical nanocomposite SiC/holey-graphene/holey-MnO2 (SiC/HG/h-MnO2) with tailored porosity by knitting together the quasi-aligned single-crystalline doped 3C-SiC nanowire array and in situ surface-reduced holey graphene framework into a three-dimensional quasi-ordered structure, which enables the mass growth of ultrathin h-MnO2 nanosheets at approximately practical levels of mass loading. The produced synergistically favorable interconnected porous architecture allows for the highly efficient electron transfer and rapid ion transport up to interior surfaces of the network. Remarkably, the all-solid-state flexible asymmetric supercapacitors (ASCs) made with SiC/HG/h-MnO2 and SiC/graphitic carbon (GC) nanoarrays are mechanically robust and show a high areal capacity (0.32 mWh cm-2) and a high rate capability (280 mW cm-2) at ultrahigh mass loading (6.5 mg cm-2), much higher than most of previous superior SCs in aqueous or gelled electrolytes and thus offer an entirely new prototype of textile-based ASCs, which represents a critical step toward practical applications for various portable electronics.

Coupling Topological Insulator SnSb2 Te4 Nanodots with Highly Doped Graphene for High-Rate Energy Storage.

Topological insulators have spurred worldwide interest, but their advantageous properties have scarcely been explored in terms of electrochemical energy storage, and their high-rate capability and long-term cycling stability still remain a significant challenge to harvest. p-Type topological insulator SnSb2 Te4 nanodots anchoring on few-layered graphene (SnSb2 Te4 /G) are synthesized as a stable anode for high-rate lithium-ion batteries and potassium-ion batteries through a ball-milling method. These SnSb2 Te4 /G composite electrodes show ultralong cycle lifespan (478 mAh g-1 at 1 A g-1 after 1000 cycles) and excellent rate capability (remaining 373 mAh g-1 even at 10 A g-1 ) in Li-ion storage owing to the rapid ion transport accelerated by the PN heterojunction, virtual electron highways provided by the conductive topological surface state, and extraordinary pseudocapacitive contribution, whose excellent phase reversibility is confirmed by synchrotron in situ X-ray powder diffraction. Surprisingly, durable lifespan even at practical levels of mass loading (>10 mg cm-2 ) for Li-ion storage and excellent K-ion storage performance are also observed. This work provides new insights for designing high-rate electrode materials by boosting conductive topological surfaces, atomic doping, and the interface interaction.

Significance of iron compounds in chemical and electro‐oxidation treatment of sugar industry wastewater: Batch reaction

AbstractIndustrialization plays a major role in a nation's growth. However, with an increase in industrial activities, pollution levels are also increasing. Among all industries, the sugar‐processing industry is one that requires large amounts of water to process the sugar, and, consequently, it discharges large amounts of water as effluent. Highly polluted wastewater brings changes to the physicochemical characteristics of the surrounding environment. Iron compounds have had a significant impact when they are used in wastewater treatment in various applications, including when they are used to minimize the pollution levels in sugar industry wastewater (SIWW). To minimize the pollutant levels from SIWW, iron compounds have been key for uses in treatments involving chemical and electro‐oxidation. Two different methodologies of electrocoagulation and chemical coagulation have been used to treat SIWW. In electrocoagulation, an iron plate is used as an electrode material under specific operating conditions. Ferrous sulfate and ferric chloride have been used as chemical coagulants at various pH and mass loading levels. The use of iron metals shows an 82% reduction in chemical oxygen demand (COD) and an 84% reduction in color at the optimum condition of pH 6, an electrode distance of 20 millimeters, and a current density of 156 square centimeters. As a chemical coagulant, iron salt (ferrous sulfate) provides a reduction of 77% COD and a 91% reduction of color at pH 6 and a 40‐millimole mass loading. Electrochemical treatment using iron was found to be suitable to treat SIWW. The sludge generated after treatment can be burned or composted with the possible recovery of some of the treatment costs.

Additive-Assisted Novel Dual-Salt Electrolyte Addresses Wide Temperature Operation of Lithium-Metal Batteries.

In this study, self-synthesized lithium trifluoro(perfluoro-tert-butyloxyl)borate (LiTFPFB) is combined with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to formulate a novel 1 m dual-salt electrolyte, which contains lithium difluorophosphate (LiPO2 F2 ) additive and dominant carbonate solvents with low melting point and high boiling point. The addition of LiPO2 F2 into this novel dual-salt electrolyte dramatically improves cycleability and rate capability of a LiNi0.5 Mn0.3 Co0.2 O2 /Li (NMC/Li) battery, ranging from -40 to 90 °C. The NMC/Li batteries adopt a Li-metal anode with low thickness of 100 µm (even 50 µm) and a moderately high cathode mass loading level of 10 mg cm-2 . For the first time, this paper provides valuable perspectives for developing practical lithium-metal batteries over a wide temperature range.

Remarkable enhancement in the electrochemical activity of maricite NaFePO4 on high-surface-area carbon cloth for sodium-ion batteries

The electrochemical reversibility of maricite NaFePO4 is highly dependent on the rational design of the nanostructure. We propose, for the first time, an effective strategy of applying an acid-etched carbon cloth (eCC) as the substrate to be loaded with NaFePO4@C and significantly enhance the electrochemical activity of the maricite. The electrochemical test results show that the NaFePO4@C loaded on eCC exhibits a much higher reversible capacity (142 mAh g−1 at 0.1 C) than that (107 mAh g−1 at 0.1 C) of the material loaded on an Al current collector. Moreover, compared to that of the untreated carbon cloth (CC), NaFePO4@C loaded on eCC shows a superior rate performance and ultralong cycling lifetime at high mass loading levels. The excellent electrochemical performance of the NaFePO4@C-eCC electrode benefits from the regular grooves on the surface of the eCC, which provide a significantly larger surface area that is favorable to NaFePO4@C strongly and uniformly binding onto the carbon fibers. The self-supporting electrode configuration, that is, without the addition of an inactive binder and conductive additives, facilitates fast ion/electronic transport and reduces the aggregation of the NaFePO4@C particles. This work is expected to provide a new route for achieving high electrochemical activity in NaFePO4.

Facile and scalable preparation of 3D SnO2/holey graphene composite frameworks for stable lithium storage at a high mass loading level

A binder-free 3D SnO2/holey graphene composite framework electrode with high mass loading shows superior Li+ storage performance.

Surface Gradient Ti-Doped MnO2 Nanowires for High-Rate and Long-Life Lithium Battery.

Cryptomelane-type α-MnO2 has been demonstrated as a promising anode material for high-energy Li-ion batteries because of its high capacity and intriguing [2 × 2] tunnel structure. However, applications of MnO2 electrode, especially at high current rates and mass active material loading, are limited by the poor mechanical stability, unstable solid electrolyte interphase layer, and low reversibility of conversion reactions. Here, we report a design of homogeneous core-shell MnO2 nanowires (NWs) created by near-surface gradient Ti doping (Ti-MnO2 NWs). Such a structurally coherent core-shell configuration endowed gradient volume expansion from the inner core to the outer shell, which could effectively release the stress of the NW lattice during cycling and avoid pulverization of the electrode. Moreover, the gradiently doped Ti is able to avoid the Mn metal coarsening, reducing the metal particle size and improving the reversibility of the conversion reaction. In this way, the Ti-MnO2 NWs achieved both high reversible areal and volumetrical capacities (2.3 mA h cm-2 and 991.3 mA h cm-3 at 200 mA g-1, respectively), a superior round-trip efficiency (Coulombic efficiency achieved above 99.5% after only 30 cycles), and a long lifetime (a high capacity of 742 mA h g-1 retained after 3000 cycle at 10 A g-1) at a high mass loading level of 3 mg cm-2. In addition, the detailed conversion reaction mechanism was investigated through in situ transmission electron microscopy, which further evidenced that the unique homogeneous core-shell structure could largely suppress the separation of core and shell upon charging and discharging. This new NW configuration could benefit the design of other large-volume-change lithium battery anode materials.

Generalized 3D Printing of Graphene-Based Mixed-Dimensional Hybrid Aerogels.

Graphene-based mixed-dimensional materials hybridization is important for a myriad of applications. However, conventional manufacturing techniques face critical challenges in producing arbitrary geometries with programmable features, continuous interior networks, and multimaterials homogeneity. Here we propose a generalized three-dimensional (3D) printing methodology for graphene aerogels and graphene-based mixed-dimensional (2D + nD, where n is 0, 1, or 2) hybrid aerogels with complex architectures, by the development of hybrid inks and printing schemes to enable mix-dimensional hybrids printability, overcoming the limitations of multicomponents inhomogeneity and harsh post-treatments for additives removal. Importantly, nonplanar designed geometries are also demonstrated by shape-conformable printing on curved surfaces. We further demonstrate the 3D-printed hybrid aerogels as ultrathick electrodes in a symmetric compression tolerant microsupercapacitor, exhibiting quasi-proportionally enhanced areal capacitances at high levels of mass loading. The excellent performance is attributed to the sufficient ion- and electron-transport paths provided by the 3D-printed highly interconnected networks. The encouraging finding indicates tremendous potentials for practical energy storage applications. As a proof of concept, this general strategy provides avenues for various next-generation complex-shaped hybrid architectures from microscale to macroscale, for example, seawater desalination devices, electromagnetic shielding systems, and so forth.

Efficiency of Electrodynamic Dust Shield at Dust Loading Levels Relevant to Solar Energy Applications

In this study, laboratory measurement of dust removal efficiency of electrodynamic dust shield (EDS) prototypes was carried out using a real-world dust at mass loading levels relevant to solar energy applications. A removable dielectric cover method was employed to gravimetrically determine the dust removal efficiency. Three EDS prototypes with the same electrode configuration but different areas were used. The results suggest that scale-up does not negatively affect the EDS dust removal efficiency. However, the EDS dust removal efficiency decreased with decreasing dust loading, and it dropped significantly when the total dielectric cover thickness increased from 0.27 to 0.37 mm. Much of the persistent dust consisted of particles μ m, but these small particles constitute a large fraction of dust in the field. Depositing dust through a mesh sieve led to unnatural apparent size distribution, due to particle agglomeration. Future EDS studies need to use dust deposition methods that better simulate natural dust accumulation.

Three-Dimensional Holey-Graphene/Niobia Composite Architectures for Ultrahigh-Rate Energy Storage

Nanostructured electrode materials have shown considerable promise for electrochemical energy storage with ultrahigh energy density or powder density. However, such performance was often achieved in electrodes with rather low mass loading (e.g., ~1 mg cm-2 or less), which cannot be readily scaled to electrodes having practical levels of mass loading (e.g., > 10 mg cm-2) due to ion diffusion limitations in thicker electrodes. As a result, the scaled areal capacity or current density of these nanostructured electrodes rarely exceeds those of today’s Li-ion batteries. To sustain the same gravimetric capacity and current density in thicker electrodes with 10 times greater mass loading (e.g., 10 vs. 1 mg cm-2) requires to deliver 10 times more charges over 10 times longer distance, which represents a fundamental scientific challenge in electrode architecture design rather than a simple engineering scaling matter. Herein we report the design of a three-dimensional (3D) holey-graphene/niobia (Nb2O5) composite for ultrahigh-rate energy storage at practical levels of mass loading (>10 mg cm-2). The highly interconnected graphene network in the 3D architecture provides excellent electron transport properties, while its hierarchical porous structure facilitates rapid ion transport. By systematically tailoring the porosity in the holey graphene backbone, charge transport in the composite architecture is optimized to deliver high areal capacity and high-rate capability at high mass loading, which represents a critical step forward towards practical applications.