Search

• Introduces fabrication-scale solvent-free dry electrode process with PTFE binder. • Defines unit process, equipment, intermediate products, and characterization methods. • Interprets the relationship between intermediate products and cell performance. Conventional wet-electrode manufacturing encounters challenges in producing thicker electrodes due to issues related to solvent evaporation. This study introduces a novel method for fabricating solvent-free dry electrodes using polytetrafluoroethylene (PTFE) as a binder, representing a significant advancement in electrode manufacturing processes. By eliminating the use of solvents, this method not only addresses these challenges but also offers a scalable and practical solution for mass production. The process is meticulously structured into sequential unit operations, each specifically tailored for a distinct function, utilizing the distinctive fibrillation properties of PTFE. Intermediate product specifications for each phase are clearly defined, accompanied by a comprehensive analysis of both physical and electrochemical performances. This analysis highlights the influence of varying PTFE contents and properties on the microstructure of the dry electrode. Notably, the study achieves a significant breakthrough with an electrode formulation of NCM811/PTFE/carbon black (CB)/carbon nanotube (CNT) = 96/2.0/1.8/0.2, which demonstrates exceptional discharge rate capability of 80 % at a 0.5 C-rate (5 mA/cm2) under the demanding parameters of 10 mAh/cm2 and 3.8 g/cc. This approach not only enhances the microstructural properties of dry electrodes but also paves the way for environmentally friendly and efficient electrode manufacturing for future energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Modified Box-Behnken L15 matrix used to define the experimental space. • Selected experimental outputs divided on two groups: feasibility and performance. • Mono- and multi-variant analysis of six experimental outputs performed. • Derringer-Suich's desirability functions applied to find the optimum. The battery R&D process should be accelerated towards a faster transition to a greener economy. However, typical battery electrode/electrolyte optimization process is still based on heuristic trial-and-error methodology, which is simple and robust but requires multiple attempts and, as a result, is high resource-time consuming. Therefore, a holistic algorithm for the optimization of a four-component (graphite, carbon black, thickener and binder) waterborne negative electrode formulation for lithium-ion batteries is proposed to improve efficiency, spend fewer resources, and speed-up the whole process. Briefly, the experimental space of possible electrode formulations is defined using a modified Box-Behnken cube matrix L15. Each inactive component's pre-selected range of content is divided into three symmetric levels. Fifteen slurries-electrodes are prepared and comprehensively studied by different experimental methods to obtain six preliminarily selected experimental outputs divided into two groups: feasibility (slurry rheology and electrode peel resistance) and electrochemical performance in half coin cells (initial coulombic efficiency and discharge capacity under 2D discharge C-rate) and full coin cells (inverse capacity degradation slope under 2C/2D cycling protocol and inverse internal cell resistance). Finally, a multi-variant analysis of the obtained experimental data array coupled with Derringer-Suich desirability functions specially defined for each experimental output are applied to find out an optimal negative electrode formulation with the best combination of the feasibility and electrochemical performance. [ABSTRACT FROM AUTHOR]

Distinct corroded behaviour and their difference between the solution and as-prepared slurry made by Maleic acid and NMP. Once the colourless and clarify solution (Maleic acid in NMP) contact the surface of clean copper foil, the solution will turn into pale-green then blue-green in several hours, and the ordered corroded product (brick-like structure) is observed. On the other side, when slurry casted on the copper foil, the corroded product formed the sphere structure for the coordination of binder (PVDF) and conductive agent (Acetylene black). Combined with the colour change of solution and the element distribution results, It's believed that the corrosion happened when we prepared the electrode with NMP as dispersant, relevant electrochemical performance tests also proof this conclusion. [Display omitted] • A new point of view is developed for lithium storage capability of maleic acid. • The possibility of corrosion with current collector is took into consideration. • An opinion for the adaptation between dispersant and organic electrode materials. Maleic acid, as a small molecular organic compound, has been manifested to demonstrate remarkable lithium storage capability with twelve electrons transferred in the reaction. Herein, we try to understand the underlying reasons for the gradual ascent of capacity during the first several cycles by focusing on the interface between the electrode slurry and the current collector copper foil. As the results show, a chemical reaction happens when the electrode slurry contacts the copper foil and a copper-bearing compound is in-situ constructed. Further investigations reveal that the capacity is mainly contributed by the corroded product of maleic acid instead of maleic acid itself. These findings offer new insights into the electrochemical behavior of maleic acid and provide a reference for the development of organic electrode materials in the future. [ABSTRACT FROM AUTHOR]

This study demonstrates the preparation of well aligned-carbon nanotube (WA-CNT) arrays onto a carbon paper substrate with a conductive carbon-black layer by the catalyst seed-impregnated chemical vapor deposition method. The prepared WA-CNT arrays were then characterized by scanning electron microscopy for different growth temperatures, standard linear velocities of feed vapors, and ferrocene-to-xylene ratios in the feed vapors. Results indicate that the optimal WA-CNT arrays of length 40–50 μm and diameter 30–40 nm were obtained at the growth temperature range of 750–800 °C, standard linear velocity of 1.40 cm s −1 , and ferrocene-to-xylene molar ratio of 1:50–1:30. These results provide new insights into the growth mechanism of CNT arrays, which involves cross-coupling of chemical reaction and mass transfer based on reaction engineering theory. The samples prepared in the study can be used as catalyst supports in air electrodes considering their three-dimensional porous structure, approximately linear channel, controllable length and diameter distribution, and excellent CNT conductivity. Electrochemical measurement indicated that the WA-CNT arrays/carbon-black layer/carbon paper substrate composites achieved relatively high discharge capacity of 2930 mAh g −1 (CNTs) at a current density of 0.05 mA cm −2 in Li–air batteries, which far exceeded other carbonaceous materials in Li–air batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gr coating reduces the dependence of ICE of SiO x on CB content. • Gr sheets slide on the interfaces between active particles and suppress the AG damage. • SiO x @Gr/AG anodes show self-adaptive behaviors during charge–discharge process. • Self-adaptive design improves capacity retention with high volumetric capacities. Si-based materials are promising high-capacity anodes, which can improve the energy density of Li-ion batteries (LIBs) that are required for the advancement of electric vehicles. Nevertheless, the severe volume change of Si-based materials during repeated cycles limits their widespread applications in LIBs. Here, we report a durable and high-energy blended anode composed of artificial graphite (AG) and graphene (Gr)-coated SiO x (SiO x @Gr) particles. The Gr coating reduces the electrode swelling during repeated cycles and increases the initial Coulombic efficiency of SiO x. This further increases the areal capacity owing to the reduction of carbon black (CB) content to 3 wt%. The SiO x @Gr/AG blended anode exhibits excellent properties compared to the bare SiO x /AG anode. These results can be attributed to the self-adaptive behavior by Gr sheets coated on SiO x particles, which mitigates the mechanical damage on the AG particles and maintains the electron conduction pathways. Hence, the reversibility of the charge–discharge reactions improves, as revealed by Raman spectral mapping and powder flowability measurements. Furthermore, the full-cell with the SiO x @Gr/AG anode exhibits good cycling stability and high volumetric capacities over 300 cycles compared to the full-cell with the bare SiO x /AG anode and AG-only anode, demonstrating the applicability of the high-capacity Si-based anodes for LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A superior carbon black as conducting additive and LIB and NIB anodes is developed. • The superior carbon black is synthesized by amorphization and pre-lithiation/sodiation. • Electrochemical mechanism of the superior carbon black is elucidated using various analytical techniques. • The superior carbon black compensates ICE and increases the reversible capacity of anode materials. Carbon black (CB) is an inexpensive and widely used carbonaceous material. However, the reversibility between CB and Li or Na is very poor, and the initial coulombic efficiency (ICE) is so low that it cannot be used as an electrode material for rechargeable batteries. In this study, we successfully designed superior CB as a high-performance conducting additive for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) using a simple two-step strategy: amorphization and pre-lithiation/sodiation. The Li- and Na-reversible capacities of amorphized CB increased significantly from 213 to 564 mAh g−1 for LIB and from 92 to 209 mAh g−1 for NIB; however, the corresponding ICEs of 61.5% for LIB and 33.5% for NIB are poor. The poor ICEs are supplemented via pre-lithiation/sodiation in the amorphized CB, which show over 100% ICEs with high Li- and Na-reversible capacities. Specifically, the modified CB has highly reversible capacities (>500 mAh g−1 for LIB, >300 mAh g−1 for NIB) with exceptionally high ICEs (133% ICE for LIB, 160% ICE for NIB), stable reversible capacities for over 100 cycles (470 mAh g−1 for LIB, 278 mAh g−1 for NIB), fast rate capabilities with highly reversible capacities at a 3C rate (~330 mAh g−1 for LIB, ~190 mAh g−1 for NIB), and excellent cycling behavior for over 300 cycles at a 1C rate. When used as a conducting additive, this CB contributes to high electrical conductivity and increase of ICE and the reversible capacity for LIB and NIB anode materials. These results are expected to have a significant impact on LIBs and NIBs. [ABSTRACT FROM AUTHOR]