Electrodes For Secondary Batteries Research Articles

Synergistic Effect of a Dual-Salt Liquid Electrolyte with a LiNO3 Functional Additive toward Stabilizing Thin-Film Li Metal Electrodes for Li Secondary Batteries.

Li metal thickness has been considered a key factor in determining the electrochemical performance of Li metal anodes. The use of thin Li metal anodes is a prerequisite for increasing the energy density of Li secondary batteries intended for emerging large-scale electrical applications, such as electric vehicles and energy storage systems. To utilize thin (20 μm thick) Li metal anodes in Li metal secondary batteries, we investigated the synergistic effect of a functional additive (Li nitrate, LiNO3) and a dual-salt electrolyte (DSE) system composed of Li bis(fluorosulfonyl)imide (LiTFSI) and Li bis(oxalate)borate (LiBOB). By controlling the amount of LiNO3 in DSE, we found that DSE containing 0.05 M LiNO3 (DSE-0.05 M LiNO3) significantly improved the electrochemical performance of Li metal anodes. DSE-0.05 M LiNO3 increased the cycling performance by 146.3% [under the conditions of a 1C rate (2.0 mA cm-2), DSE alone maintained 80% of the initial discharge capacity up to the 205th cycle, whereas DSE-0.05 M LiNO3 maintained 80% up to the 300th cycle] and increased the rate capability by 128.2% compared with DSE alone [the rate capability of DSE-0.05 M LiNO3 = 50.4 mAh g-1, and DSE = 39.3 mAh g-1 under 7C rate conditions (14.0 mA cm-2)]. After analyzing the Li metal surface using scanning electron microscopy and X-ray photoelectron spectroscopy, we were able to infer that the stabilized solid electrolyte interphase layer formed by the combination of LiNO3 and the dual salt resulted in a uniform Li deposition during repeated Li plating/stripping processes.

Rational construction of ternary ZnNiP arrayed structures derived from 2D MOFs for advanced hybrid supercapacitors and Zn batteries

Exploiting nickel-based phosphide electrodes for next-generation high-performance supercapacitors and secondary batteries with high security has attracted great attentions. Herein, we fabricated binderless ZnNiP electrode based on Ni metal-organic framework and the optimized Zn-doping process, which achieved high electrochemical performance both in hybrid supercapacitor and Zn battery. Encouragingly, the addition of Zn source and the phosphating process make a component synergy with enhanced electronic conductivity, enriched electrochemical active centers and redox reactions. The ZnNiP-0.5 with sturdy construction exhibits a remarkable specific capacity and a good cycling stability in alkaline electrolyte. When assembled to hybrid supercapacitor, the installation delivers a maximum energy density of 67.4 Wh kg−1, a maximum power density of 15.9 kW kg−1, and outstanding cycling performance (88% retention after 10 000 cycles). Additionally, the fabricated Zn battery could achieve discharge voltage of~ 1.9 V, with an admirable energy density of 529.58 Wh kg−1 and also shows the excellent durability (capacity retention of 91.6% after 3000 cycles). This work offers a feasible route and provides a certain guiding significance for the reasonable design of binder-free electrodes with delicate structures and compositions, which may inspire new significative findings of building electrodes for high-security hybrid supercapacitors and alkaline batteries.

NiCoS/carbon black based bifunctional air electrode for Zn-air secondary batteries

Nickel cobalt sulfide bifunctional catalysts were synthesized on a carbon black (CB) catalyst support through hydrothermal and solvothermal methods for the oxygen reduction (ORR) and evolution reactions (OER) in secondary rechargeable Zn-air batteries. It was found that NiCo2S4/CB was more suitable to be synthesized using ethylene glycol as the dispersing agent than water, and had better ORR/OER catalytic activities than the NiCoS composites with other Ni/Co ratios. In particular, NiCo2S4 showed significantly enhanced electrocatalytic activities when incorporated with CB to form NiCo2S4/CB, with superior ORR/OER electrocatalytic activities compared to NiCo2O4/CB. Even though, the ORR electrocatalytic activity was lower compared to Pt/C, NiCo2S4/CB showed a significantly superior OER activity (~ 0.75 V @ 10 mA cm−2), demonstrating better overall bifunctional characteristics towards the ORR and OER. The NiCo2S4/CB based bifunctional air electrode in a Zn-air single cell exhibited a higher stability (≤1.0 V charge/discharge plateau separation for 400 cycles) and longer cycle life (>500 cycles) than Pt/C (~ 250 cycles), and so has potential commercial viability.

Recent applications of the liquid phase plasma process

In this paper, the principle and application of plasma are briefly described, and in particular, the principle and practical application for plasma generated in liquid are introduced. Also, the research results of water treatment, synthesis of metal nanoparticle, synthesis of visible light-responsive photocatalyst, synthesis of energy material, and hydrogen gas production, which were tested using liquid phase plasma, are introduced. Various water pollutants were treated and hydrogen gas was produced using the strong chemical oxidizing species and ultraviolet rays in the plasma field generated in the reactant aqueous solution during the liquid phase plasma (LPP) process. The effects of plasma discharge conditions, dissolved oxygen concentration, pH value, photocatalytic behavior, as well as the properties of organic solutions on the LPP reaction were investigated experimentally and reported. Based on these previous studies, metal nanoparticles were synthesized using hydrogen atom radicals as well as the numerous electrons in the plasma field generated during the LPP process. Additionally, these studies indicate that visible light-responsive photocatalysts can be obtained when metal nanoparticles are precipitated in TiO2. They also provide evidence that metal nanoparticles can be precipitated in various carbon materials for application as electrodes in secondary batteries and supercapacitors. Therefore, the LPP process has been successfully applied in various fields given that it can be easily and conveniently used, and presently it is being applied in several new fields and many possibilities for its future application are expected.

Monoclinic and Orthorhombic NaMnO2 for Secondary Batteries: A Comparative Study

In this manuscript, we report a detailed physico-chemical comparison between the α- and β-polymorphs of the NaMnO2 compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic α-NaMnO2 shows larger reversible capacity exceeding 175 mAhg−1 at 10 mAg−1.

Analytical solution of piggyback stacked dual transmission line model as an equivalent circuit of electrode for solid-electrolyte lithium ion secondary batteries

Analytical solution of piggyback stacked dual transmission line model as an equivalent circuit of electrode for solid-electrolyte lithium ion secondary batteries

Cetrimonium bromide assisted formation of antimony alloy nanorods for use as an anode in lithium-ion and sodium-ion full-cells

Practical application of antimony alloy based electrodes in alkali-ion secondary batteries are viable due to their low-cost and widespread abundance. Employing unique nanostructuring strategies is vital for significantly improving their electrochemical performance while simultaneously addressing their inherent drawbacks. In this study, we report a simple microwave-hydrothermal approach for preparing antimony and tin-antimony alloy nanorods for the first time. Detailed X-ray diffraction and transmission electron microscopy measurements reveal that the preferential adsorption of cetrimonium bromide molecules on the (110) planes of the precursor alloy nanoparticles results in the formation of self-assembled nanorods with an average aspect ratio of 6. When mixed with nitrogen-doped graphene flakes, these nanorods deliver reversible discharge capacities of 500 mAh g−1 and 350 mAh g−1 at the end of 200 cycles in Li+ and Na+ half-cell configurations, respectively. When coupled with a LiNi0.5Mn1.5O4 cathode, the resulting Li+ full-cell delivers a nominal working voltage of 4.3 V, a high energy density of 344 Wh kg−1full-cell, and an 87.5% capacity retention after 200 cycles. Similarly, when coupled with a Prussian blue analog cathode, the resulting Na+ full-cell also delivers a nominal working voltage of 2.5 V, an energy density of 250 Wh kg−1full-cell, and an 82.5% capacity retention after 100 cycles.

High Rate Performance of Zinc-Nickel Secondary Battery Using Robust Zinc Electrode

A zinc rechargeable battery is one of the most promising candidates of next-generation energy storage devices with some merits such as a high energy density and a low-cost material, although no zinc has been used as the negative electrode for secondary uses. This is because some dendrites are generated on the zinc electrode during charge, which causes an internal short circuit. Our recent work [1] has developed a new zinc electrode that can operate at 1 C in alkaline aqueous solutions for 5,500 cycles or more, during which the charge and discharge voltages were stable and the initial capacity was kept over 90 %. In this work, we used this robust zinc electrode in zinc-nickel secondary batteries and examined high rate performance of the cell to know the cell resistance.The new zinc electrode used a copper plate as the current collector, on which zinc had been deposited by electroplating, and was designed so that the electrolyte was separated in some parallel zones. A nickel electrode and a 6 mol/L KOH solution containing saturated ZnO were also used to fabricate a zinc-nickel cell. The cell was operated at room temperature and the cell voltages during charge and discharge were measured. The operation was carried out with the following rate pattern: 1 C (1 min.) → 2 C (2 sec.) → 1 C (1 min.) → 4 C (2 sec.) → 1 C (1 min.) → 6 C (2 sec.) → 1 C (1 min.) → 8 C (2 sec.) → 1 C (1 min.) → 10 C (2 sec.). This pattern was repeated three times during each of discharge and charge. The capacity of the zinc electrode was calculated from the weight of deposited zinc and the C rate was further determined with the electrode’s capacity. The SOC range for charge and discharge was changed to know the effects on the rate performance and the cell resistance.The discharge voltage was stable even at 10 C and changed immediately from 1 C to 10 C or vice versa. The plots of the discharge voltage and the current density showed a linear relationship, and the cell resistance ranged from 1.0 ohm cm2 to 1.2 ohm cm2 in the SOC region between 40 % and 100 %. These results suggest that it is possible for the cell to discharge at 10 C in maximum with such a low cell resistance and respond to the rate change. The charge voltage at 2 C or 4 C was almost constant in 2 sec., while that at 6C, 8C, or 10 C changed 20 mV in maximum during the short period. The charge voltage at 1 C after 10 C charge was almost the same as that before it, indicating a quick charge response to the rate change even during charge. The charge voltage was also linear to the current density, and the cell resistance was 1.2 ohm cm2 to 1.4 ohm cm2 from the Ⅰ-Ⅴ relationship which excluded the charge voltage data suggesting hydrogen evolution. From the above results, we demonstrated that the new zinc electrode worked well in the zinc-nickel secondary cell at high rate up to 10 C and responded well to a quick change in C rate without dendrite issues. This work was financially supported by DOWA TECHNO FUND of DOWA Holdings, Co., Ltd.Reference[1] T. Okumura, K. Kawaguchi, M. Morimitsu, TMS 2020, San Diego (2020).

A rod-on-tube CoMoO4@hydrogel composite as lithium-ion battery anode with high capacity and stable rate-performance

Hierarchical materials have been considered promising for secondary battery electrodes owing to their capability of accommodating volumetric change of active materials and providing short pathways for rapid transportation of ions and electrons. Herein, we present a rod-on-tube composite consisting of cobalt molybdate (CoMoO4) nanotubes coating with polyaniline (PANI) hydrogel nanorods, which exhibits a high electrochemical performance as Li-ion battery anode. The hierarchical CoMoO4@PANI is prepared through in-situ polymerizing PANI nanorods on the CoMoO4 nanotubes. The rod-on-tube structure could alleviate the volumetric change of CoMoO4 during lithiation-delithiation, and improve conductivity for electron transfer. When cycling at 0.5 A g-1, the presented CoMoO4@PANI anodes exhibit a large capacity of 805 mAh g-1 after 150 cycles along with a Coulombic efficiency of 99%, which are both exceeding those of the pristine CoMoO4. A well-recoverable rate-performance is achieved. Furthermore, the density of state (DOS) and band gap of the CoMoO4@PANI and pristine CoMoO4 are also investigated by using density functional theory (DFT) calculations.

Electrochemical Studies of the Nickel‐based Hydroxide Electrode for the Oxygen Evolution Reaction and Coulombic Efficiency of the Electrode

AbstractNickel hydroxide, Ni(OH)2 electrode material has been used as a positive electrode in commercial alkaline secondary batteries for more than 100 years. This is because Ni(OH)2 has a good high rate discharge ability performance, wide operation and storage temperature range and relatively low. However, the Ni(OH)2 positive electrode exhibits poor performance which results from (i) competitive reactions of the oxidation of the active material and evolution of oxygen. (ii) The reduced charge acceptance of Ni(OH)2 positive electrode is suspected to be related to a relatively long distance between Ni(OH)2 particles and the nearest portion of the substrate. In this study, electrodes are prepared using β‐Ni(OH)2 powder as the active electrode material, hot‐pressed onto a nickel mesh current collector. The Ni2+ in the compound β‐Ni(OH)2 material is partially substituted with Co2+ and Al3+ metals and the performance of as‐prepared materials are optimized and examined. XRD, FTIR, TG‐DTA, SEM/EDS, and ICP confirms the formation of the expected compositions. The samples with 5 wt.% Co2+, and 10 wt.% Al3+ metals are found to be the optimal compositions with promising electrochemical activities. The modification of Ni(OH)2 by the partial substitution of Co2+ and Al3+ metals for Ni2+ shows some effect on the redox peaks of Ni(OH)2 and the oxygen evolution reaction (OER). E.g. the onset for oxidation of the active material is significantly improved with partial substitution of Ni2+ by Co2+. On the other hand partial substitution of Ni2+ with Al3+ moves the onset of electrode oxidation to higher potential. In addition, the partial substitution of 10 wt.% Al3+ metal improves both discharge capacity (from 128 mAh/g to 170 mAh/g), and the coulombic efficiency (from 87 % to 93 %) of the β‐Ni(OH)2 electrode.

The influence of copper and carbon black on electrochemical behavior of nickel positive electrode

Nickel hydroxide is used as an active material in positive electrodes of secondary alkaline batteries. In alkaline batteries, the capacity of the negative electrode is greater than that of the positive electrode, hence the cell capacity is limited by the positive electrode. The practical capacity of the Ni(OH) 2 positive electrode depends on the efficiency of the conductive network connecting the Ni(OH) 2 particles with the current collector. In this study, hot-pressed-type electrodes were prepared using fiber-like β-Ni(OH) 2 powder as the active material on a nickel mesh as a current collector. The effect of carbon black as a conductive network for Ni(OH) 2 active material and the partial substitution of Cu(OH) 2 for β-Ni(OH) 2 material on the electrode performance, are examined. The carbon black powder addition improves the utilization of the active material; however it lead to a decrease in stability of the electrode. The partial substitution of Cu(OH) 2 for β-Ni(OH) 2 significantly improves the coulombic efficiency of the β-Ni(OH) 2 active material and it also increases the specific discharge capacity and enhance the stability of the electrode. These findings showed that the copper modified β-Ni(OH) 2 electrodes possessed an improved specific capacity and stability and thus may be recognized as a promising hybrid material for battery electrode applications. • The β-phase Ni(OH) 2 is formed when hydrothermal treatment is applied. • Carbon black improves specific discharge capacity but not stability. • Cu 2+ substitution improves both capacity and stability.

Understanding the Surface Film Formation on Si Electrodes in Lithium Secondary Batteries with Atomic Force Microscopy.

The solid electrolyte interphase formation on the negative electrodes of lithium secondary batteries has been considered as one of the principal issues limiting the performance of batteries. Si is an attractive electrode material for improving energy density of lithium secondary batteries because of its high specific theoretical capacity (4200 mAh g-1). However, solid electrolyte interphase formation on Si-based electrodes have not been clearly understood in spite of its significance. Herein, the solid electrolyte interphase formation on Si electrodes in electrolyte solutions containing ethylene carbonate or propylene carbonate was investigated by using in-situ atomic force microscopy. Large and irreversible capacity fade in SiO electrodes was confirmed in both electrolyte solutions through cyclic voltammetry and charge/discharge testing. The in-situ atomic force microscopy results indicated that the decomposition reaction occurred in the ethylene carbonate-based electrolyte solution at a potential of ~0.68 V, while the lithium alloying reaction occurred below 0.25 V during the first reduction process. The decomposition reaction was more vigorous and occurred at a higher potential in the propylene carbonate-based electrolyte solution, resulting in the formation of a thick solid electrolyte interphase film. These results suggest that the solid electrolyte interphase formation on Si electrodes is strongly influenced by the composition of the electrolyte solution.

Mechanical Integrity of Conductive Carbon-Black-Filled Aqueous Polymer Binder in Composite Electrode for Lithium-Ion Battery.

The mechanical stability of aqueous binder and conductive composites (BCC) is the basis of the long-term service of composite electrodes in advanced secondary batteries. To evaluate the stress evolution of BCC in composite electrodes during electrochemical operation, we established an electrochemical–mechanical model for multilayer spherical particles that consists of an active material and a solid-electrolyte-interface (SEI)-enclosed BCC. The lithium-diffusion-induced stress distribution was studied in detail by coupling the influence of SEI and the viscoelasticity of inorganic-filler-doped polymeric bonding material. It was found that tensile hoop stress plays a critical role in determining whether a composite electrode is damaged or not—and circumferential cracks may primarily initiate in BCC, rather than in other electrode components. Further, the peak tensile stress of BCC is at the interface with SEI and does not occur at full lithiation due to the relaxation nature of polymer composite. Moreover, mechanical damage would be greatly misled if neglecting the existence of SEI. Finally, the structure integrity of the binder and conductive system can be effectively improved by (1) increasing the carbon black content as much as possible in the context of meeting cell capacity requirements—it is greater than 27% and 50% for sodium alginate and the mixtures of carboxy styrene butadiene latex and sodium carboxymethyl cellulose, respectively, for composite graphite anode; (2) reducing the elastic modulus of SEI to less than that of BCC; (3) decreasing the lithiation rate.

Advances in Manufacturing Composite Carbon Nanofiber-Based Aerogels

This article provides an overview on manufacturing composite carbon nanofiber-based aerogels through freeze casting technology. As known, freeze casting is a relatively new manufacturing technique for generating highly porous structures. During the process, deep cooling is used first to rapidly solidify a well-dispersed slurry. Then, vacuum drying is conducted to sublimate the solvent. This allows the creation of highly porous materials. Although the freeze casting technique was initially developed for porous ceramics processing, it has found various applications, especially for making aerogels. Aerogels are highly porous materials with extremely high volume of free spaces, which contributes to the characteristics of high porosity, ultralight, large specific surface area, huge interface area, and in addition, super low thermal conductivity. Recently, carbon nanofiber aerogels have been studied to achieve exceptional properties of high stiffness, flame-retardant and thermal-insulating. The freeze casting technology has been reported for preparing carbon nanofiber composite aerogels for energy storage, energy conversion, water purification, catalysis, fire prevention etc. This review deals with freeze casting carbon nanofiber composite materials consisting of functional nanoparticles with exceptional properties. The content of this review article is organized as follows. The first part will introduce the general freeze casting manufacturing technology of aerogels with the emphasis on how to use the technology to make nanoparticle-containing composite carbon nanofiber aerogels. Then, modeling and characterization of the freeze cast particle-containing carbon nanofibers will be presented with an emphasis on modeling the thermal conductivity and electrical conductivity of the carbon nanofiber network aerogels. After that, the applications of the carbon nanofiber aerogels will be described. Examples of energy converters, supercapacitors, secondary battery electrodes, dye absorbents, sensors, and catalysts made from composite carbon nanofiber aerogels will be shown. Finally, the perspectives to future work will be presented.

Synthesis of Na-MnO₂ Electrodes and Its Microstructural and Electrochemical Characterization.

The batteries are portable devices that allow to storage chemical energy and provide electric current directly. Inside the batteries, one of the most used materials is Lithium, which includes a large number of applications.In recent years, the investigation of ion-Na and Na-MnO₂ batteries has been intensified as an alternative to Li-MnO₂ batteries. Lithium and sodium have many similar chemical characteristics and their low cost and the wide availability of sodium are factors that can make them more used in the future. An important concern in the increase of lithium battery production lies in the limited natural resources provided by this material, and its heterogeneous distribution in the earth's crustThis work is focused on the preparation of Na-MnO₂ electrodes for secondary batteries and the microstructural, structural, and electrochemical characterization of them. The synthesis technique was hydrothermal non-conventional type. The contributions are found in the comparison of the properties and electronic elements of the synthesized materials. The impact of this project is on the possible use of Na-MnO₂ electrodes as an alternative material to the one currently used in Li-MnO₂ batteries. Figure 1

Zeolite based gas-diffusion electrodes for secondary metal air batteries

In recent years, secondary metal air batteries have received considerable attention as promising technology for energy storage in combination with renewable energy sources. The oxidation of carbon in conventional gas-diffusion electrodes reduces the life of the secondary metal-air batteries. Replacement of the carbon-based material with zeolite is a possible solution for overcoming this problem which is the aim of this work.Zeolite is a natural or synthetic porous material which provides the necessary gas permeability. The required hydrophobicity of the electrodes is ensured by mixing the zeolite with an appropriate amount of polytetrafluoroethylene following a specially developed procedure.The experiments are performed in a home designed test cell which ensures measurements in both half-cell and full cell configuration. In this study the testing is carried out in 3-electrode homemade half-cell configuration with hydrogen reference electrode. The cell was subjected to cycling at charge/discharge current ± 2 mA/cm2 respectively.The obtained results show that the replacement of carbon with zeolite in the gas diffusion layer is a promising direction for optimization of the gas diffusion electrode.

Physical property control for innovative powder processes – Rheological control of concentrated slurry and wet granules

The manufacture of materials using slurry-based processes, such as the electrodes of Lithium ion secondary batteries and fuel cells, can be made more productive by increasing the concentration of the slurry or adopting wet granules with extremely high concentrations.Shear thickening, which is a particular issue for such highly concentrated slurries, is derived from collisions between particles, it is important to control the size, size distribution, and concentration of particles, as well as the solvent viscosity. Furthermore, the controlling of electrostatic interaction between particles and mixing of different size particles have direct impacts on shear thickening, the concentration of salt in the slurry and size and mixing ratio of particles are also important characteristics. It may be possible to control rheological behavior using these characteristics.The amount of solvent is reduced beyond the level in a concentrated slurry, the slurry changes from a so-called liquid state to a solid state of wet granules. Fully utilizing the properties of these wet granules would maximize various advantages in the production process. Flowability is the most important characteristic for use of highly concentrated wet granules. This research found that flowability is extremely low when the strain is low, but that higher wet granule concentrations flow more easily under high strain.Our latest research about rheological behavior of concentrated slurry and wet granules open up to the possibilities for ultimate form of the electrode manufacturing process might involve film-creation or forming using particles without any liquid content at all. Resolving issues such as the uniformity of the blended powder and flowability control may enable conventional slurry processes to be replaced by powder processes.

Zeolite Based Air Electrodes for Secondary Batteries

In recent years, secondary batteries received considerable attention as promising technology for energy storage in combination with renewable energy sources. The oxidation of carbon in conventional air electrodes reduces the life of secondary batteries. One possible solution for overcoming this problem is the replacement of carbon material with zeolite.Zeolite is a natural or synthetic porous material with crystalline structure which provides the necessary gas permeability. The required hydrophobicity of the electrode is ensured by mixing zeolite with an appropriate amount of polytetrafluoroethylene following a specially developed procedure. The main purpose of the present research is to discover the optimum level of hydrophobicity (impregnation) of zeolite. Moreover, appropriate amount of PTFE will ensure better mechanical stability and long charge/discharge cycle life.The results from this study show that the replacement of carbon with zeolite in the gas diffusion layer is a promising direction for optimization of the bi-functional air electrode. The relationship between the particle size and the hydrophobicity of the electrode was found. It was found that the mechanical stability and hydrophobicity of the electrode improved with the replacement of the emulsion powder. The gas permeability is maintained in the norms, which guarantees the good performance of the electrode. More than 200 charge/discharge cycles were reached.

Effect of Transitional Metals (Mn and Ni) Substitution in LiCoPO4 Olivines.

Transition metal substitution is a key strategy to optimize the functional properties of advanced crystalline materials used as positive electrodes in secondary lithium batteries (LIBs). Here we investigate the structural alterations in the olivine lattice of Mn and Ni substituted LiCoPO4 phase and the impact on performance in LIBs. X-ray diffraction (XRD) and extended X-ray absorption experiments have been carried out in order to highlight the structural alterations induced by partial substitution of cobalt by manganese and nickel. XRD analysis suggests that substitution induces an expansion of the lattices and an increase of the antisite disorder between lithium and transition metal ions in the structure. XAS data highlight negligible electronic disorder but a relevant modulation in the local coordination around the different metal ions. Moreover, galvanostatic tests showed poor reversibility of the redox reaction compared to the pure LCP sample, and this failure is discussed in detail in view of the observed remarkable structural changes.

Improving zinc porous electrode for secondary alkaline batteries: Toward a simple design of optimized 3D conductive network current collector

The internal migration of zinc within the thickness of porous composite negative electrodes for rechargeable zinc batteries causes detrimental shape change of the zinc electrode. It depends on various parameters linked to the electron conduction in the electrode: electronic percolation, conductive additives, primary current collector. This study highlights a simple solution, that drastically enhances the electrochemical performance of thick and porous zinc electrodes, by rethinking their architecture. Using a multiplicity of thin current collectors enables to create a 3D network of electronic percolation and a better repartition of the current lines within the electrode; as a result, the formation of multiple active zinc cores in the electrode volume is better controlled. This strategy allows to improve the management of zinc migration within the electrode structure, leading to minimal densification of each zinc core, and overall enables higher reversibility of zinc oxidation/reduction upon discharge/charge. It finally mitigates the initial drastic capacity fading observed on standard type calcium zincate negative electrode.