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Prussian blue (PB) and its analogues (PBAs) are promising cathode materials for sodium ion batteries (SIBs) because of their wide diffusion tunnels for sodium ions. However, water molecules typically contained within PB structures have been hypothesized to undermine their stability and rate performance. Here we report that zeolite water molecules in PB structures may induce the formation of Na2CO3 as one of the main components in SEI layer on the surface of PB materials. From PB samples containing zeolite water synthesized via a solvothermal method at different temperatures, a specific capacity of 113 mAh g−1 is demonstrated at 10 mA g−1, with a capacity retention of 75% at 1000 mA g−1. Cycling tests reveal a capacity loss of only 1.2% after 100 cycles at 200 mA g−1. It is suggested that Na2CO3 contained in the SEI layer not only protects the electrode materials from side reactions with the electrolyte, but also facilitates quick charge transfer at the interfaces, leading to improved electrochemical performances.
Pd-coated manganese dioxide catalysts (Pd@MnO2) were synthesized by depositing Pd on the surface of β-MnO2 nanorod particles in aqueous solutions at room temperature. TEM, XRD and electrochemical characterizations indicated that the MnO2 nanorods were successfully coated with Pd particles when the Pd weight percentage was more than 4.6%. The activities of the Pd@MnO2 catalysts for oxygen reduction reaction (ORR) were investigated using a rotating disk electrode (RDE) and a rotating ring-disk electrode (RRDE). The ORR onset potentials on the Pd@MnO2 catalyst shifted positively for more than 250mV compared with the MnO2 catalyst without Pd coatings. Both the ORR onset potentials and the limiting current density obtained by the RDE measurements on the Pd@MnO2 catalysts were close to those on the Pd black catalyst. The mass activity of the Pd@MnO2 catalysts (normalized by Pd mass) was 2.5 times higher than that of the Pd black catalyst. Based on the Tafel slopes of the Pd@MnO2 catalysts (which is about 60mVdec−1 at low overpotentials), and based on the fact that the activation energies of the Pd@MnO2 catalysts are very close to the activation energies of the Pd catalysts, one may conclude that the small amount of Pd coating provides the primary ORR activity of the Pd@MnO2 catalysts.
Three-dimensional (3D) a-Fe2O3@graphene aerogel (a-Fe2O3@GA) composites with an a-Fe2O3 content as high as 54wt% were prepared via a gas-liquid interfacial assembly method. It was found that the a-Fe2O3 nanoparticles were well dispersed and embedded into the 3D porous structure of graphene aerogel (GA). Compared with that (SBET =82m2 g−1) of pristine a-Fe2O3, the resulting composites exhibited much higher specific surface area (SBET =261m2 g−1). The composites used as anode materials for lithium ion batteries maintained a high reversible capacity of 745mAhg−1 at a current density of 100mAg−1 or more than 240mAhg−1 at a current density of 2000mAg−1 after 100 cycles, and exhibited superior stable electrochemical cycling performance and excellent rate capability. The superior electrochemical performances were attributed to the synergistic effects of the unique 3D porous structure of the composites with high contents of well dispersed a-Fe2O3.
The layered oxide compounds xLi2MnO3·(1 − x)LiMO2 (M = Ni, Mn, Co) are of great interest as positive electrode materials for high energy density lithium-ion batteries. In-situ neutron diffraction was carried out to compare the structural changes between the classical layered compound Li[Ni1/3Mn1/3Co1/3]O2 (x = 0) and lithium-excess layered compound Li[Li0.2Ni0.18Mn0.53Co0.1]O2 (x = 0.5) during electrochemical cycling. In this work, lab made pouch cells were built for the in-situ study and graphite was used as the anode material. Irreversible structural change of Li[Li0.2Ni0.18Mn0.53Co0.1]O2 during first charge (4.7 V)/discharge cycle (2.0 V) was indicated by dynamic changes in lattice d-spacing, while the Li[Ni1/3Mn1/3Co1/3]O2 showed completely reversible structural evolution between 4.4 V and 2.5 V. Ex-situ neutron powder diffraction was performed on both pristine and chemically delithiated lithium-excess layered compounds to better understand the irreversible structure change.
Parasitic reactions between Li metal and electrolytes need to be mitigated in Li-metal batteries. Here, the authors report the use of a fluorinated orthoformate-based electrolyte, leading to a monolithic solid–electrolyte interphase and subsequently a high-performance Li-metal battery.
The key challenge in fabricating three-dimensional (3D) microbatteries is the achievement of high-aspect-ratio electrodes to ensure dramatic improvement in the surface-to-volume ratio and charge/discharge rates without a corresponding increase in overall volume. In this work, we present the design of a novel 3D-interlaced microbattery (3D-IMB) for high-energy-density applications. 3D-interlaced structures have been fabricated on a silicon substrate provided with arrays of interlaced micro-containers of anode and cathode materials separated by a porous-silicon wall. Etching of the interlaced structure was performed by photolithography and dry reactive ion-etch process. The nanoporous separator (membrane) between the micro-containers was formed by a metal-assisted anisotropic wet-etching process. Different etching solutions, containing hydrogen peroxide, hydrofluoric acid and ethanol, were tested in order to obtain the proper pore-size in the inter-container partitions. Cycling tests of Li/MoO x S y thin-film planar microbatteries with interlaced porous-silicon structures showed stable electrochemical behavior.
Charge transport in a Nafion® membrane incorporating zinc(II) phthalocyanine (ZnPc) was studied using spectrocyclic voltammetry (SCV) and potential-step chronocoulospectrometry (PSCCS) techniques. The visible absorption spectra of the membrane depended on the ZnPc concentration in the membrane, showing the formation of the ZnPc dimer. The equilibrium constant between the monomer and dimer of ZnPc in the membrane was calculated as 75 M−1. It was found that the charge transport occurs by two processes; the first process was considered to be the charge injection from the electrode to the ZnPc present in close proximity to the electrode, and the second one, bulk charge transport in the membrane. The apparent rate constant for the presumed charge injection was estimated as 1.6×10−2 s−1. The bulk charge transport in the membrane was analyzed as a combination of a physical displacement of ZnPc and charge hopping between them considering the equilibrium between the monomer and dimer of ZnPc. This analysis shows that the charge transport takes place by physical displacement of the ZnPc monomer and not by charge hopping, and that the contribution of the dimer to the charge transport is negligible. The first order rate constant (k p) of the physical displacement of the ZnPc monomer was estimated as 3.3×10−3 s−1. The saturated fraction of the oxidized ZnPc in the membrane decreased with the ZnPc concentration in the membrane because of the bulk charge transfer decreased by the formation of the ZnPc dimer.
Aims Type 2 diabetes, hyperinsulinemia, and insulin resistance are associated with cognitive impairment. Experimental studies indicate that insulin signaling in the brain is related to cognitive performance. Here we evaluated whether insulin-related variables contribute to the variance in cognitive performance among individuals with type 2 diabetes. Methods A total of 806 individuals with type 2 diabetes (mean age 62±8years, HbA1c 6.9±1.1%) completed a neuropsychological test battery. Insulin-related variables evaluated were: fasting plasma insulin, C-peptide, and the Homeostasis Model Assessment (HOMA2-IR; in individuals without insulin treatment; n=641). The unadjusted coefficient of determination (R2), obtained from multiple linear regression analyses, was used to estimate the proportion of variance in cognition explained by insulin-related variables. Results Sex, age, and educational level together explained 18.0% (R2) of the variance in memory function, 26.5% in information processing speed, and 22.8% in executive function and attention. Fasting insulin, C-peptide, or HOMA2-IR did not increase the explained variance (maximum ΔR2 0.3%, P≥0.14). Similar results were obtained when insulin-related variables were added to models that additionally included glycemic control, cardiovascular risk factors, and depression. Conclusions Our results show that measures of peripheral insulin resistance are unrelated to cognitive performance among individuals with adequately controlled type 2 diabetes.
Highly crystalline, size-controlled Zn2SnO4 nanoparticles are synthesized by hydrothermal synthesis using two different mineralizers, viz., inorganic Na2CO3 and organic tert-butyl amine. The shape and surface properties of the two types of nanoparticles are totally different owing to the structure-directing abilities and the radicals in the mineralizers, even though both types of nanoparticles show a defect-free and highly crystalline structure. Na2CO3 induces faceted planar morphologies with negative surface charges, whereas tert-butyl amine induces roughly spherical shapes with positive surface charges; these changes have been analyzed by SEM, TEM, and zeta potential measurements. Electrochemical tests performed on these two types of nanoparticles indicate a capacity that gradually fades up to the 20th cycle due to the inevitable structural irreversibility. However, the specific discharge/charge capacities of both Zn2SnO4 anodes become almost constant after 20 cycles, and at 40th cycle, the specific discharge capacities of both nanoparticles are 521.4mAhg−1 for nanoparticles synthesized using tert-butyl amine and 448.0mAhg−1 for nanoparticles synthesized using Na2CO3 with Coulombic efficiencies higher than 96%. Such an excellent cycling stability and reversibility against lithium insertion/extraction can be attributed to the improved pulverization/agglomeration resistances of these materials, resulting from the surface residual charges, i.e., the repulsive forces between like-charged nanoparticles.
Vanadium redox flow batteries (VRFBs) have attracted considerable attention for potential use in the development of large-scale energy storage systems. However, the commercialization of VRFBs is still challenging because of their various overpotentials, which are due to the poor reversibility and electrochemical activity of graphite felt (GF) electrodes. In this study, we fabricated a NiO-decorated GF electrode that exhibited a clear electrocatalytic effect on the V2+/V3+ and VO2+/VO2 + redox reactions. Vanadium ions preferentially attached to each NiO site because of strong electrostatic affinity to the local negatively charged O2− species. In particular, a significant amount of NiO bound to graphite by replacement of hydrogen from the hydroxyl groups with nickel ion, leading to an increase in the ratio of carboxyl groups to hydroxyl groups. The increase in the number of carboxyl groups also improved the VRFB performance, since the carboxyl functional group on GF surface acts as effective catalyst for the vanadium redox reactions. Furthermore, NiO nanoparticles enhanced the mass-transfer property of vanadium ions by the increased area and hydrophilicity of the electrode surface. To optimize the electrode structure for high electrochemical performance, the crystallinity and morphology of the NiO catalyst on GF were controlled via the operating temperature and precursor concentration. When optimized NiO/GF300 was applied to VRFBs, it exhibited high energy efficiency (74.5%) at a high current rate (125 mA cm−2), compared with GF without the catalyst (55.4%). Moreover, NiO-decorated GF exhibited durability and stability in acidic electrolyte during long-term operation for 300 cycles.
The galvanostatic growth of PbSO4 on Pb in H2SO4 was studied using scanning electron microscopy and in situ transmission X-ray microscopy (TXM). Images from the TXM are used to investigate the effects of sodium lignosulfonate on the PbSO4 formation and the initial growth of the PbSO4 crystals. Sodium lignosulfonate is shown to retard, on average, the growth of the PbSO4 crystals, yielding a film with smaller crystals and higher crystal densities. In addition, results from experiments with and without sodium lignosulfonate indicate an increase in the nucleation rate of the PbSO4 crystals when the oxidation current is applied, which was attributed to an increase in the supersaturation of the electrolyte. Furthermore, an analysis of the growth rates of individual, large crystals showed an initial rapid growth which declined as the PbSO4 surface coverage increased. It was concluded that the increase in PbSO4 provides additional sites for precipitation and reduces the precipitation rate on the existing crystals. Finally, the potential-time transient at the beginning of oxidation is suggested to result from the relaxation of a supersaturated solution and the development of a PbSO4 film with increasing resistance.
As lithium ion cells age, they experience power and energy fade associated with impedance rise and capacity loss, respectively. Identification of key aging parameters in lithium ion battery models can validate degradation hypotheses and provide a foundation for State of Health (SOH) estimation. This paper develops and simplifies an electrochemical model that depends on two key aging parameters, cell resistance and the solid phase diffusion time of Li+ species in the positive electrode. Off-line linear least squares and on-line adaptive gradient update processing of voltage and current data from fresh and aged lithium ion cells produce estimates of these aging parameters. These estimated parameters vary monotonically with age, consistent with accepted degradation mechanisms such as solid electrolyte interface (SEI) layer growth and contact loss.
This investigation focuses on the preparation of polypyrrole composite films, Ppy/Al2O3/Al, used as solid-state capacitor with electrochemical polymerization in the presence of DBSA, co-dopant and co-solvent. The parameters of the solid-state capacitor, i.e. leakage current (Lc), capacitor (Cs), dicipation factor (DF) and equivalent series resistance (ESR), were measured in this study. The surface morphology and compositions of the prepared Ppy/Al2O3/Al electrolyte were examined using SEM and EDS, respectively. Further, for 3C of electricity passed, the values of Lc, Cs, DF and ESR of the Ppy/Al2O3/Al capacitor prepared with 2-NSNa and DBSA as a co-dopant were measured to be 0.029±0.005μAcm−2, 688.8±8.28nFcm−2, 14.35±5.63% and 18.63±3.48Ω. Further, the parameters both of R ox and R ppy are 135.5 and 7.047Ω.
State of charge (SoC) is an important parameter for li ion battery (LiB) cells, and its estimation should be done online as its continuous operation before recharge depends on its SoC. While Coulomb counting method (also called Coulometry) is useful to estimate the SoC online, its accuracy depends on the value of its initial maximum capacity. Presently, this capacity is obtained by the periodic discharge of the cell fully but this can introduce damage to the cell and shorten its lifespan. In this work, an electrical model is developed for LiB cells based on the principle of electrochemistry from its discharge curve (i.e. the change in terminal voltage over time within a discharge cycle). This model is able to compute the internal parameters of a cell, including its maximum initial capacity at the beginning of each discharge cycle. With the internal parameters computed, it can also produce its Nyquist plot and the plot is found to agree well with its experimental electrochemical impedance spectroscopy (EIS) spectra. With this model, the status of a LiB cell and its maximum charge capacity can be determined in real time.
A series of LiNi0.5Co0.5− x Ti x O2 (0⩽ x ⩽0.5) are prepared by a tartaric acid-assisted sol–gel technique. The phase formation process is observed by TG–DTA. It is found that the target product appears at a temperature higher than 400°C and completes to phase formation at 700°C. The crystal structure and morphology are characterized by XRD, SEM and Raman spectroscopy. XRD patterns show that the as-prepared sample transforms from hexagonal structure into cubic structure with the increase of Ti content in LiNi0.5Co0.5− x Ti x O2. Raman spectra also demonstrate the successive substitution of Ti for Co in the structure with band blue-shift phenomenon. SEM images confirm that the as-prepared sample exhibits narrow and regular particles with the size between 0.5 and 1.5μm. The apparent particle size of sample starts to decrease with x ⩽0.1, and the gradually increases by introducing Ti dopant with higher content (x ⩾0.15). The electrochemical behavior of the sample displays different characteristics after Ti substitution. It is found that the initial working potential increases with the increase of Ti doping content. As a result, the initial lithium storage capacity for trace Ti-doped sample is higher than that delivered by the pristine one. The decrease of reversible capacity for high degree Ti-doped sample is ascribed to the electrochemical inactivity of the cubic compound in the sample. Therefore, trace Ti doping is beneficial to achieve promising cathode material for lithium-ion batteries.
Solar photovoltaic trees (SPVT's) are chosen as an alternative option for electricity generation due to numerous benefits (especially in land utilization, urban infrastructure, and landscaping). Currently, SPVT's are available in many designs, and one among them is the novel phyllotaxy pattern. Technically, SPVT's seem to be more reliable and cost-effective. The expected average lifetime of the photovoltaic (PV) modules used in SPVT's is around 25 years. Once, the lifetime is over, these SPVT's must undergo a waste management process, and the scope for recycling is very high. Even though the scope for PV waste recycling is very high, many recyclers face the problems especially in estimating material recovery potential. In this paper, thermal and chemical treatments based end-of-life (EOL) method is used to estimate the material recovery potential from the phyllotaxy pattern-based SPVT. Initial estimations on the total embodied materials of the SPVT system is evaluated based on the components material fraction. Next, under the applied EOL management method, material recovery potential is estimated as per the material (aluminum, copper, glass, silver, and steel). Lastly, a few limitations with this EOL method are highlighted, and presented results aim to serve as useful data for the recyclers to have decisions.
Carbon nanobeads (CNBs) were prepared by reacting cyclohexachlorobenzene with dispersed sodium metal at 200°C for 4h. The CNBs prepared in this manner formed uniform nanobeads, with sizes ranging from 100 to 300nm. Heating resulted in a reduction in the size of the CNBs, and improvements in their degree of crystallinity. The nanosized carbon materials considerably increased the surface area of the powder, reducing the distance of the intercalation/deintercalation pathway, substantially improving the charge capacity of the lithium ion battery at a high charging rate. The charge capacity of CNBs was found to be 238mAhg−1, while that of commercial MCMB reached only 36mAhg−1, when the charging rate was 1C (372mAhg−1). As the charging rate was further increased to 2C (744mAhg−1) and 3C (1116mAhg−1), the charge capacities of CNBs dropped to 173 and 111mAhg−1, respectively. The cyclic performance of the CNBs was measured and found to be significantly improved in comparison to other carbonaceous materials, for up to 100 cycles. Although cyclic performance did result in a gradual reduction in capacity, the CNBs still greatly exceeded the capacity of MCMB. These results clearly demonstrate the potential role of CNBs as anodes for high capacity Li ion batteries for use in the automobile industry.
Publisher Summary This chapter reviews the idealized types of reactors used for industrial purposes. The chapter discusses the properties and applications of such reactors in the chemical process industries. A reactor is a piece of equipment in which the feedstock is converted to the desired product. Reactors are chosen such that they meet the requirements imposed by the reaction mechanisms, rate expressions, and the required production capacity. Other parameters that must be determined to choose the correct type of reactor are reaction heat, reaction rate constant, heat transfer coefficient, and reactor size. Reactors that are free of the effect of the macrokinetic properties are classified as: batch isothermal perfectly stirred reactor, batch adiabatic perfectly stirred reactor, semi-batch perfectly stirred reactor, continuous isothermal perfectly stirred reactor flow reactor, continuous adiabatic perfectly stirred flow reactor, continuous isothermal plug flow reactor, and continuous adiabatic plug flow reactor. This chapter also reviews the multiphase reactors such as the fixed and fluidized beds.
Biomass-derived carbon materials have aroused widespread concern as host material of sulfur to enhance electrochemical performances for lithium–sulfur batteries. Herein, goat hair, as a low-cost and eco-friendly precursor, is employed to fabricate cauliflower-like in-situ nitrogen, oxygen and phosphorus tri-doped porous biomass carbon (NOPC) by a facile activation with H3PO4 and carbonization process. The morphology and microstructure of NOPC can be readily tuned by altering pyrolysis temperature. The as-prepared NOPC matrix material carbonized at 600 °C possesses 3D hierarchical porous structure, high specific surface area (535.352 m2 g−1), and appropriate pore size and pore size distribution. Encapsulating sulfur into the NOPC depends on a stem-melting technology as cathode materials of Li–S batteries. Due to the synergistic effect of special physical structure and inherent tri-doping of N, O and P, electrons and ions transfer and utilization of active sulfur in the materials are improved, and the shuttle behaviors of soluble lithium polysulfides are also mitigated. Consequently, the S/NOPC-600 composite exhibits excellent electrochemical performance, giving a high initial discharge capacity of 1185 mA h g−1 at 0.05 C and maintaining a relatively considerable capacity of 489 mA h g−1 at 0.2 C after 300 cycles. Our work shows that a promising candidate for cathode material of Li–S batteries can be synthesized using low-cost and renewable biomass materials by a facile process.
Different sizes of layered CoOOH were synthesized by the molten-salt-assisted method at different temperatures. X-ray diffraction and scanning electron microscope studies reveal that CoOOH grew at (003) with increasing temperature, and its size can reach dozens of microns. X-ray absorption near edge structure and XPS studies demonstrate that the Co valence state of CoOOH-750 is trivalent, and X-ray Absorption Fine Structure shows that it had a higher symmetry and lower disorder degree, indicating that CoOOH-750 has higher crystallinity and Co3+. The results of electrochemical tests show that CoOOH-750 exhibited the best oxygen-evolution-reaction (OER) catalytic activity.
Next-generation high-energy batteries will require a rechargeable lithium metal anode, but lithium dendrites tend to form during recharging, causing short-circuit risk and capacity loss, by mechanisms that still remain elusive. Here, we visualize lithium growth in a glass capillary cell and demonstrate a change of mechanism from root-growing mossy lithium to tip-growing dendritic lithium at the onset of electrolyte diffusion limitation. In sandwich cells, we further demonstrate that mossy lithium can be blocked by nanoporous ceramic separators, while dendritic lithium can easily penetrate nanopores and short the cell. Our results imply a fundamental design constraint for metal batteries (“Sand's capacity”), which can be increased by using concentrated electrolytes with stiff, permeable, nanoporous separators for improved safety.