Regulating electrostatic phenomena by cationic polymer binder for scalable high-areal-capacity Li battery electrodes

Fast-Charging Lithium-Ion Batteries Enabled by Magnetically Aligned Electrodes

With the increasing popularity of electric transportation over the past several years, fast-charging lithium-ion batteries are highly demanded for shortening electric vehicles' charging time. Extensive efforts have been made on material development and electrode engineering; however, few of them are scalable and cost-effective enough to be potentially incorporated into the current battery production. Here, we propose a facile magnetic templating method for preparing LiFePO4 (LFP) cathodes with vertically aligned graphene sheets to realize fast-charging properties at a practical loading of 20 mg cm-2. Graphene sheets decorated with Fe3O4 nanoparticles can be responsive to an external magnetic field and can maintain their vertical alignment during the electrode fabrication process. The vertically aligned graphene provides the magnetized LFP electrodes (m-LFP) with simultaneously improved electron and lithium-ion transport properties, achieving 110 and 76 mA h g-1 at 3C and 4C, respectively. Furthermore, magnetized Fe3O4 (m-Fe3O4) anodes were also prepared via the magnetic templating method to vertically align the Fe3O4 nanosheets inside, which outperforms the conventional graphite anodes at a high rate of 3C. Finally, by pairing the magnetized LFP cathode and Fe3O4 anode, we demonstrate the simultaneous fast-charging properties and good cycling stability in the m-LFP||Fe3O4 full cells. This study not only provides an effective methodology for achieving vertically aligned structures which can potentially be incorporated into industrial manufacturing but also brings insightful considerations for designing scalable fast-charging energy storage systems.

Cellulose Elementary Fibrils as Deagglomerated Binder for High-Mass-Loading Lithium Battery Electrodes

Amidst the ever-growing interest in high-mass-loading Li battery electrodes, a persistent challenge has been the insufficient continuity of their ion/electron conduction pathways. Here, we propose cellulose elementary fibrils (CEFs) as a class of deagglomerated binder for high-mass-loading electrodes. Derived from natural wood, CEF represents the most fundamental unit of cellulose with nanoscale diameter. The preparation of the CEFs involves the modulation of intermolecular hydrogen bonding by the treatment with a proton acceptor and a hydrotropic agent. This elementary deagglomeration of the cellulose fibers increases surface area and anionic charge density, thus promoting uniform dispersion with carbon conductive additives and suppressing interfacial side reactions at electrodes. Consequently, a homogeneous redox reaction is achieved throughout the electrodes. The resulting CEF-based cathode (overlithiated layered oxide (OLO) is chosen as a benchmark electrode active material) exhibits a high areal-mass-loading (50 mg cm-2, equivalent to an areal capacity of 12.5 mAh cm-2) and a high specific energy density (445.4 Wh kg-1) of a cell, which far exceeds those of previously reported OLO cathodes. This study highlights the viability of the deagglomerated binder in enabling sustainable high-mass-loading electrodes that are difficult to achieve with conventional synthetic polymer binders.

Chelated Metal-Organic Frameworks for Improved the Performance of High-Nickel Cathodes in Lithium-Ion Batteries

Lithium-ion batteries have gained widespread use in various applications, including portable devices, electric vehicles, and energy storage systems. High Ni cathode, LiNixCoyMnzO2 (NCM, x≥0.8, x+y+z=1), have garnered significant attention owing to their high energy density. However, the limited Li-ion transfer rate and transition metal cross-talk to anode pose obstacles to further improvement of electrochemical performance. To tackle these challenges, metal-organic frameworks (MOFs) with chelating agents are employed as additive materials for electrode. MOFs with chelating agents offer three key attributes: (1) Effective mitigation of transition metal cross-talk to the anode, (2) Partial desolvation of Li+ ions through MOF pores, and (3) Immobilization of anions via metal sites in the MOF. Leveraging these advantages, the chelating MOF-modified NCM cathode demonstrates reduced charge transfer resistance, both in their pristine and cycled states. In addition, they exhibit significantly improved the Li-ion diffusion coefficients after 100 cycles. These findings underscore the potential of MOFs with chelating agents as promising additive materials for enhancing the performance of LIBs.

Zwitterionic Polymer Binder Networks with Structural Locking and Ionic Regulation Functions for High Performance Silicon Anodes

The silicon anode suffers from significant volume expansion, low electrical conductivity, and poor long-term cycling performance, which collectively limit its potential to replace graphite as the anode material for lithium-ion batteries. In this article, a PAA-p(HEA-SBMA) binder was prepared by an in situ thermal cross-linking method, which combines strong mechanical properties and excellent reaction kinetics. The synergy of covalent bonding, dynamic hydrogen bonding, and ionic interactions in the binder structure provides excellent mechanical strength, which effectively dissipates stresses and "locks" the entire structure. In addition, the zwitterionic monomers in the binder structure improve the transport of lithium-ions and promote lithium salt dissociation, which helps to establish a stable solid electrolyte interphase (SEI). Thanks to the structural locking mechanism and dynamic ionic regulation function, the PAA-p(HEA-SBMA) binder exhibited a long cycling performance. Even after 1000 cycles at 0.5 C, it still has a discharge capacity of 981.63 mAh g-1. The multifunctional binder designs in this work provide insights into the advancement of high energy density lithium-ion batteries.

Polymerizable Ionic Liquid-Based Gel Polymer Electrolytes Enabled by High-Energy Electron Beam for High-Performance Lithium-Ion Batteries

Polymerizable ionic liquid-based gel polymer electrolytes (PIL-GPEs) were developed for the first time using high-energy electron beam irradiation for high-performance lithium-ion batteries (LIBs). By incorporating an imidazolium-based ionic liquid (PIL) into the polymer network, PIL-GPEs achieved high ionic conductivity (1.90 mS cm-1 at 25 °C), a lithium transference number of 0.62, and an electrochemical stability exceeding 5 V. E-beam irradiation enabled rapid polymer network formation within a metal-cased battery structure, eliminating the need for initiators and improving the process efficiency. In the NCM811/PIL-GPE/Li cells, PIL-GPE (8:2) delivered an initial discharge capacity of 198.8 mAh g-1 with 82% retention at 100 cycles, demonstrating enhanced thermal stability and cycling performance compared to traditional GPEs. The demonstrated PIL-GPEs demonstrate strong potential for high-stability, high-performance LIB applications.

Three-dimensional high-aspect-ratio microarray thick electrodes for high-rate hybrid supercapacitors

Hybrid supercapacitors (HSCs) with facile integration and high process compatibility are considered ideal power sources for portable consumer electronics. However, as a crucial component for storing energy, traditional thin-film electrodes exhibit low energy density. Although increasing the thickness of thin films can enhance the energy density of the electrodes, it gives rise to issues such as poor mechanical stability and long electron/ion transport pathways. Constructing a stable three-dimensional (3D) ordered thick electrode is considered the key to addressing the aforementioned contradictions. In this work, a manufacturing process combining lithography and chemical deposition techniques is developed to produce large-area and high-aspect-ratio 3D nickel ordered cylindrical array (NiOCA) current collectors. Positive electrodes loaded with nickel-cobalt bimetallic hydroxide (NiOCA/NiCo-LDH) are constructed by electrodeposition, and HSCs are assembled with NiOCA/nitrogen-doped porous carbon (NiOCA/NPC) as negative electrodes. The HSCs exhibits 55% capacity retention with the current density ranging from 2 to 50 mA cm-2. Moreover, it maintains 98.2% of the initial capacity after long-term cycling of 15,000 cycles at a current density of 10 mA cm-2. The manufacturing process demonstrates customizability and favorable repeatability. It is anticipated to provide innovative concepts for the large-scale production of 3D microarray thick electrodes for high-performance energy storage system.

Biomimetic Transparent Slippery Surface for the Locomotion of Photocontrol Droplets and Bubbles

Directed transportation and collection of liquids and bubbles play a vital role in the survival of ecosystems. Among them, the optical response control is widely used in the fields of microfluidic chips and chemical synthesis because of its high remote operation and fast response speed. However, due to poor light transmission, the development direction of traditional near-infrared (NIR) absorbing materials in the field of visualization is limited, and there are few reports of manufacturing an operating platform that can realize the directional movement of droplets/bubbles on a single platform. Here, a transparent photo-responsive PBFS platform is prepared for droplet and bubble manipulation by coating the etched glass substrate with Prussian blue (PB) nanocubes. When near-infrared (NIR) irradiation on the PBFS platform, PB nanocubes trigger heat production by photothermal means, due to the action of Marangoni force, the surface tension on the left and right sides of the droplets and bubbles is not uniform, forming a surface tension gradient, thereby driving the movement of the droplets and bubbles. The control platform has good application potential in the field of microchemical reaction and biomedical engineering and brings new solutions to the field of transparent photothermal materials.

Regulating Anode-Electrolyte Interphasial Reactions by Zwitterionic Binder Chemistry in Lithium-Ion Batteries with High-Nickel Layered Oxide Cathodes and Silicon-Graphite Anodes

The practical application of silicon (Si)-based anodes faces challenges due to severe structural and interphasial degradations. These challenges are exacerbated in lithium-ion batteries (LIBs) employing Si-based anodes with high-nickel layered oxide cathodes, as significant transition-metal crossover catalyzes serious parasitic side reactions, leading to faster cell failure. While enhancing the mechanical properties of polymer binders has been acknowledged as an effective means of improving solid-electrolyte interphase (SEI) stability on Si-based anodes, an in-depth understanding of how the binder chemistry influences the SEI is lacking. Herein, a zwitterionic binder with an ability to manipulate the chemical composition and spatial distribution of the SEI layer is designed for Si-based anodes. It is evidenced that the electrically charged microenvironment created by the zwitterionic species alters the solvation environment on the Si-based anode, featuring rich anions and weakened Li+-solvent interactions. Such a binder-regulated solvation environment induces a thin, uniform, robust SEI on Si-based anodes, which is found to be the key to withstanding transition-metal deposition and minimizing their detrimental impact on catalyzing electrolyte decomposition and devitalizing bulk Si. As a result, albeit possessing comparable mechanical properties to those of commercial binders, the zwitterionic binder enables superior cycling performances in high-energy-density LIBs under demanding operating conditions.

In Situ Self-Reconfiguration Induced Multifunctional Triple-Gradient Artificial Interfacial Layer toward Long-Life Zn-Metal Anodes

Aqueous Zn-ion batteries featuring with intrinsic safety and low cost are highly desirable for large-scale energy storage, but the unstable Zn-metal anode resulting from uncontrollable dendrite growth and grievous hydrogen evolution reaction (HER) shortens their cycle life. Herein, a feasible in situ self-reconfiguration strategy is developed to generate triple-gradient poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PDDA-TFSI)-Zn5(OH)8Cl2·H2O-Sn (PT-ZHC-Sn) artificial layer. The resulting triple-gradient interface consists of the spherical top layer PT with cation confinement and H2O inhibition, the dense intermediate layer ZHC nanosheet with Zn2+ conduction and electron shielding, and the bottom layer Znophilic Sn metal. The well-designed triple-gradient artificial interfacial layer synergistically facilitates rapid Zn2+ diffusion to regulate uniform Zn deposition and accelerates the desolvation process while suppressing HER. Consequently, the PT-ZHC-Sn@Zn symmetric cell achieves an ultralong lifespan over 6500 h at 0.5 mA cm-2 for 0.5 mAh cm-2. Furthermore, a full battery coupling with MnO2 cathode exhibits a 17.2% increase in capacity retention compared with bare Zn anode after 1000 cycles. The in situ self-reconfiguration strategy is also applied to prepare triple-gradient PT-ZHC-In, and the assembled Zn//Cu cell operates steadily for over 8400 h while maintaining Coulombic efficiency of 99.6%. This work paves the way to designing multicomponent gradient interface for stable Zn-metal anodes.

Tailoring Electric Double Layer by Cation Specific Adsorption for High-Voltage Quasi-Solid-State Lithium Metal Batteries

The interfacial instability of high-nickel layered oxides severely plagues practical application of high-energy quasi-solid-state lithium metal batteries (LMBs). Herein, a uniform and highly oxidation-resistant polymer layer within inner Helmholtz plane is engineered by in situ polymerizing 1-vinyl-3-ethylimidazolium (VEIM) cations preferentially adsorbed on LiNi0.83Co0.11Mn0.06O2 (NCM83) surface, inducing the formation of anion-derived cathode electrolyte interphase with fast interfacial kinetics. Meanwhile, the copolymerization of [VEIM][BF4] and vinyl ethylene carbonate (VEC) endows P(VEC-IL) copolymer with the positively-charged imidazolium moieties, providing positive electric fields to facilitate Li+ transport and desolvation process. Consequently, the Li||NCM83 cells with a cut-off voltage up to 4.5 V exhibit excellent reversible capacity of 130 mAh g-1 after 1000 cycles at 25 °C and considerable discharge capacity of 134 mAh g-1 without capacity decay after 100 cycles at -20 °C. This work provides deep understanding on tailoring electric double layer by cation specific adsorption for high-voltage quasi-solid-state LMBs.

Towards Efficient Polymeric Binders for Transition Metal Oxides-based Li-ion Battery Cathodes

Transition metal oxide cathodes (TMOCs) such as LiNi0.8Mn0.1Co0.1O2 and LiMn1.5Ni0.5O4 have been widely employed in Li-ion batteries (LIBs) owing to superior operating voltages, high reversible capacities and relatively low cost. Nevertheless, despite significant advancements in practical application, TMOC-based LIBs face great challenges such as transition metal dissolution and volume expansion during cycling, which jeopardizes the future advance of high-voltage TMOCs. As a critical component of cathode, polymeric binder acts as a crucial part in maintaining the mechanical and ion/electron conductive integrity between active particles, carbon additives, and the aluminum collector, hence minimizing cathode pulverization during battery cycling. Moreover, Polymeric binder with specialized functions is thought to offer a new solution to enhancing the electrochemical stability of the TMOCs. Therefore, this review aims at providing a comprehensive summary of the ideal requirements, design strategies and recent progress of polymeric binders for TMOCs. Future design perspectives and promising research technologies for advanced binders for high-voltage TMOCs are introduced.