Journal of Power Sources Advances最新文献

Copper phosphide (Cu₃P) is a potentially high volumetric capacity conversion electrode for the use in Li-ion as well as in Na-ion batteries. Here, we study the lithium and sodium storage properties of Cu₃P/Carbon (Cu₃P/C) composites containing 70 wt% Cu₃P and 30 wt% carbon black. Cu₃P is prepared by reactive ball milling from the elements while in a second step Cu₃P is mixed with carbon black by non-reactive ball milling. Structure and morphology are characterized by X-ray diffraction (XRD) as well as scanning and transmission electron microscopy (SEM, TEM). The electrochemical properties are studied in Li and Na half cells with different types of electrolytes based on carbonates (EC:DMC mixture) or diglyme, with the latter clearly leading to better results such as higher capacity, better cycle life and smaller polarization. After 120 cycles, the Li-cell showed a capacity of 210 mAh g⁻¹ while around 120 mAh g⁻¹ were found for the Na cell. The contribution of the carbon black is negligible in case of the Li cell while it becomes an important factor in the Na cell. Electrode expansion/shrinkage of the electrode during cycling (“breathing”) as determined by in situ dilatometry is fairly constant in diglyme electrolytes while rapid fading is observed in carbonate electrolytes.

Calcium-metal-anode based batteries have recently gained much attention owing to their higher theoretical capacity when compared to the commercial lithium-ion cells. However, electrodeposition of metallic calcium is challenging and currently there is only a few reported organic electrolytes allowing reversible plating/stripping, including Ca(BF₄)₂ in carbonate solvents. Many of the commercial salts are sold as hydrates, which is the case of Ca(BF₄)₂, however the drying of a divalent-metal cation organic electrolyte is not trivial. Herein, several procedures for drying BF₄⁻-based electrolytes are explored and discussed. It is shown that the tetrafluoroborate anion can easily get hydrolyzed during some drying protocols producing impurities, and thus, it is necessary to prepare the salt in anhydrous conditions to ensure low water and contaminant contents. Two different synthetic routes are presented as alternatives to the commercial hydrated salt.

As battery materials increase in energy density, the likelihood of larger morphological changes during cycling increases. Current PVDF/carbon electrode matrices are ill-prepared for such materials and new battery electrode matrices are required. Typical strategies replace PVDF by aqueous binders, utilize other carbonaceous conductive additives or add small amounts of conducting polymers. In this study, we propose a class of water-processable, self-conductive electrode matrices that relies on the combination of polyelectrolyte binders with conducting polymers. By in situ polymerizing conducting polymer monomers in an aqueous solution of carboxylate-containing polymers, new electrode matrices are synthesized, in which components are intimately mixed at the nano-scale. Herein, the molecular composite polypyrrole:carboxymethyl cellulose (PPy:CMC), as a representative electrode matrix, allows the water-based electrode fabrication of carbon-additive-free electrodes. No additional binders and conductive additives are required to fabricate electrodes due to the adhesive and conductive features of PPy:CMC composites. This study paves the way for developing a promising type of electrode matrices for Li-ion batteries based on conducting polymer molecular composites that are adhesive and conductive, ensuring high-energy-density battery materials maintain active over more cycles.

Scanning Acoustic Microscopy (SAM) is shown here for the first time to be suitable for the visualization of defects like electrolyte leakage, faulty electrodes and gas accumulation inside coin and pouch battery cells. These failures are detected through the local atypical reflection of acoustic waves at faulty interfaces. Individual images are produced from the reflected wavefronts obtained at specific time delays allowing additionally information about the depth of the investigated failures. This fast and non-destructive visualization tool can be used for the quality control of battery cells during their production, contributing to a fast and economic screening of new materials or new production steps. SAM also brings a valuable contribution on the assistance in choosing representative spots of the battery for post-mortem analyses. SAM is in its infancy regarding the characterization of batteries. Fields for further development are suggested and discussed here.

Impurities in hydrogen can have a detrimental effect on the performance of polymer electrolyte membrane fuel cells (PEMFCs) used in automotive applications. However, the establishment of reliable threshold limits for each impurity is hampered by a lack of information on the distribution and speciation of impurities within the cell, including the impact of internal reactions and gas crossover. Here we describe a novel operando method for detailed investigation of the impact of impurities on a single cell PEMFC, using a combination of isotopic labelling and measurement of gas composition at the anode exhaust via Gas Chromatography – Methaniser with Flame Ionisation Detector (GC-Methaniser-FID) and Selected Ion Flow Tube – Mass Spectrometry (SIFT-MS). We demonstrate the utility of this approach in the study of the impact of internal air bleed on carbon monoxide (CO) poisoning, enabling quantification of the surface coverage of CO on the anode catalyst as a function of cathode back-pressure. This technique shows great promise as a diagnostic tool for the investigation of the impact of a wide range of impurities at stack level (e.g. hydrocarbons, ammonia, halogenated compounds).

Lithium (Li)-rich manganese (Mn)-rich oxide (LMR) cathode materials, despite of the high specific capacity up to 250 mAh g⁻¹ suffer from instability of cathode/electrolyte interfacial layer at high working voltages, causing continuous voltage decay and capacity fading, especially at elevated temperatures. In various battery systems, localized high-concentration electrolytes (LHCEs) have been widely reported as a promising candidate to form effective electrode/electrolyte interphases. Here, an optimized LHCE is studied in graphite (Gr)-based full cells containing LMR cathode, being cycled at 25, 45 and 60 °C with the reference of a conventional LiPF₆-based electrolyte. It is revealed that the LHCE can effectively suppress continuous electrolyte decompositions and mitigate the dissolution of Mn ions due to the formation of more protective electrode/electrolyte interphases on both anode and cathode, which, in turn, lead to significantly improved cycling stability and enhanced rate capability under the selected temperatures. The mechanistic understanding on the failure of the conventional LiPF₆-containing electrolyte and the function of the LHCE in Gr||LMR cells under high temperatures provides valuable perspectives of electrolyte development for practical applications of LMR cathodes in high energy density batteries over a wide temperature range.

In the past few years, developments in anion exchange membranes (AEMs) have led to a significant increase in hydroxide conductivities, ultimately yielding striking improvements in the performance of anion exchange membrane fuel cells (AEMFCs) at low operating temperatures, usually at 40–80 °C. Aside from these remarkable achievements, the literature is void of any work on AEMFCs operated at temperatures above 100 °C, despite the consensus from various models remarking that working at higher cell temperatures may lead to many significant advantages. In this work, we present the first high-temperature AEMFC (HT-AEMFC) tested at 110 °C. The HT-AEMFC exhibits high performance, with a peak power density of 2.1 W cm⁻² and a current density of as high as 574 mA cm⁻² measured at 0.8 V. This initial work represents a significant landmark for the research and development of the fuel cell technology, opening a wide door for a new field of research we call hereafter, HT-AEMFCs.

In this work we report a detailed investigation about the self-discharge of lithium-ion capacitors (LICs). To date, this process has been only marginally investigated. However,the understanding of the dynamics of the self-discharge taking place in LICs appear of importance in view of the optimization of their performance. We showed that LIC display a rather high self-discharge, comparable to that of electrochemical capacitor, and that the main responsible for this process is the positive electrode. Furthermore, we demonstrated that the use of repeated float tests is affecting the self-discharge of LICs, and that after 50–100 h at high voltage their self-discharge is significantly reduced.

Nanocomposite catalysts composed of non-precious nanoparticles anchored by modified graphene for oxygen reduction reactions (ORRs) are the emphasis of research nowadays for wide application in electrocatalyst systems. Herein, an endeavor is made to report on a one-pot synthesis method to produce a catalyst for Fe₃O₄ and Ni–NiO nanoparticles on Polydiallyldimethylammonium chloride-modified graphenes (PDDA-G). The nanocomposite is characterized by spectral measurements, using scanning electron spectroscopy (SEM), transmitting electron spectroscopy (TEM), x-ray diffractometer (XRD) and Raman spectroscopy to reveal its microstructure. Through a layer-by-layer PDDA-G investigation, a significant anchoring of nanoparticles and maintenance of the graphene with good electron transporting properties and spatial distance in nanoscale by PDDA is achieved. Additionally, the electrochemical properties of Fe₃O₄@PDDA-G and Ni–NiO@PDDA-G are demonstrated by linear scan voltammetry (LSV) with rotation disk electrode (RDE). Fe₃O₄@PDDA-G displays prominent ORR activity in 2-electron and 4-electron pathways, and better ORR mass activities than Ni–NiO@PDDA-G and commercial Pt/C. The results of this study provide a new strategy to develop material design approaches for high-performance electrocatalysts to be employed in fuel cells.

The state-of-the-art protonic ceramic electrolyte BaCe_0.7Zr_0.1Y_0.1Yb_0.1O_3-δ (BCZYYb) dense films were successfully deposited on the pre-sintered Ni(O)+BCZYYb anode substrate by recently developed rapid laser reactive sintering (RLRS) method. The separation of the deposition of dense electrolyte from the preparation of porous anode makes it possible to manufacture protonic ceramic fuel cells (PCFCs) with more desirable electrolyte and anode microstructures. The PCFC single cells prepared after introducing the cathode thin film BaCo_0.4Fe_0.4Zr_0.1Y_0.1O_3-δ (BCFZY0.1) showed OCVs of 0.94–0.97V and peak power densities of 97 mW/cm² at 600 °C and 121 mW/cm² at 600–650 °C under Air/H₂ gradient. The proton conductivity of the BCZYYb film derived the RLRS-derived single cell showed a moderate proton conductivity of 3.7 × 10⁻³S/cm at 600 °C. The higher PCFC performance can be expected by further optimization of the thickness, compositions, and/or microstructures of the component layers.