Binder For Anode Research Articles

A highly crosslinked polymeric binder for silicon anode in lithium-ion batteries

Silicon as the anode materials had great development prospect in lithium-ion batteries owing to its high capacity. However, during the cycling process, silicon anode’s huge volume expansion would cause the material's severe crushing and disintegration. In order to effectively limited its volume expansion, designed a new highly crosslinked binder, Synthesis of Oxidized Starch (OS) and Polyacrylic Acid (PAA) by crosslinked esterification reaction, and used to reduce the negative effects of Si electrode in the cycling process. Compared to the polyacrylic acid (PAA) binder, the crosslinked polymer binder could effectively increase the Silicon anode’s electrochemical performance. The initial specific discharge capacity and coulomb efficiency of the crosslinked polymer binder electrode were 3441.7 mA h g−1 and 62.39 %, while those of the polyacrylic acid (PAA) binder electrode were only 3526.9 mA h g-1 and 53.59 %. At the current density of 200 mA g-1 after 100 cycles, the discharge capacity and capacity retention of the electrode with the crosslinked polymer binder was 1386.2 mA h g−1 and 40.28 %, greater than those of the electrodes with polyacrylic acid (1068.1 mA h g−1/30.28 %). This solution provided a design of new crosslinked polymer binder, which could be used for the pragmatic application of the anode material with large volume variation.

Polydopamine blended with polyacrylic acid for silicon anode binder with high electrochemical performance

Polyacrylic acid (PAA) is one of the commonly used binders for Si anodes in lithium battery. However, it cannot accommodate huge volume change of the Si anodes during the lithium insertion/delithiation process, which would cause a sharp attenuation of the capacity and cycle performance of the Si-based lithium batteries. Herein, we present a polydopamine (PDA)/PAA composite binder for Si anodes in lithium batteries. This PDA-PAA binder has a three-dimensional network structure and provides a strong adhesion between the active materials and the current collector. When PDA-PAA is used for Si anode, the lithium battery demonstrates a high specific capacity of 2383 mAh g−1 at the 2C with 77.7% capacity retention after 100 cycles.

A hydrophilic poly(methyl vinyl ether-alt-maleic acid) polymer as a green, universal, and dual-functional binder for high-performance silicon anode and sulfur cathode

Binders could play crucial or even decisive roles in the fabrication of low-cost, stable and high-capacity electrodes. This is especially the case for the silicon (Si) anodes and sulfur (S) cathodes that undergo large volume change and active material loss in lithium-ion batteries during prolonged cycles. Herein, a hydrophilic polymer poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was explored as a dual-functional aqueous binder for the preparation of high-performance silicon anode and sulfur cathode. Benefiting from the dual functions of PMVEMA, i.e., the excellent dispersion ability and strong binding forces, the as-prepared electrodes exhibit improved capacity, rate capability and long-term cycling performance. In particular, the as-prepared Si electrode delivers a high initial discharge capacity of 1346.5 mAh g−1 at a high rate of 8.4 A/g and maintains 834.5 mAh g−1 after 300 cycles at 4.2 A/g, while the as-prepared S cathode exhibits enhanced cycling performance with high remaining discharge capacities of 663.4 mAh g−1 after 100 cycles at 0.2 C and 487.07 mAh g−1 after 300 cycles at 1 C, respectively. These encouraging results suggest that PMVEMA could be a universal binder to facilitate the green manufacture of both anode and cathode for high-capacity energy storage systems.

Biomass-derived polymeric binders in silicon anodes for battery energy storage applications

Recent developments in silicon anode binders derived from various biomass sources, with a focus on polymer properties and their effect on battery performance.

A mechanically robust self-healing binder for silicon anode in lithium ion batteries

Both industrious and academic research societies have considered silicon (Si) as the most promising anode for next-generation lithium ion batteries (LIBs) because silicon offers more than one order of magnitude higher capacity than conventional anode materials. However, huge volume changes and pulverization of the silicon particles during the charge/discharge processes damage the longevity of Si-based LIBs. Self-healing binders could tackle this problem by in-situ repairing the damage to the silicon anode. Herein, we synthesized a novel self-healing poly(ether-thioureas) (SHPET) polymer with balanced rigidity and softness for the silicon anode. The as-prepared silicon anode with the self-healing binder exhibits excellent structural stability and superior electrochemical performance, delivering a high discharge capacity of 3744 mAh g−1 at a current density of 420 mA g−1, and achieving a stable cycle life with a high capacity retention of 85.6% after 250 cycles at a high current rate of 4200 mA g−1. The success of this work suggests that the proposed SHPET binder facilitates fast self-healing, buffers the drastic volume changes and overcomes the mechanical strain in the course of the charge/discharge process, and could subsequently accelerate the commercialization of the silicon anode.

Epoxy and amide crosslinked polarity enhanced polysaccharides binder for silicon anode in lithium-ion batteries

Natural polysaccharides are considered to be effective binders to enhance the cycle stability of silicon anode of lithium-ion batteries. However, the poor mechanical strength and relatively low binding strength have limited its further application. Epoxy and amide groups are recognized as the organic crosslinker with high polarity, which could bring qualified mechanical and binding strength. Herein, a crosslinked copolymer konjac glucomannan-g-polyacrylamide-g-glycidyl methacrylate (KPG) has been synthesized by radical polymerization reaction and applied as an aqueous binder for silicon anode materials. The introduction of polyacrylamide (PAM) and glycidyl methacrylate (GMA) improved the mechanical strength and binding strength through their high polarity and crosslinked effect. As a result, excellent electrochemical performance (capacity of 1415 mAh g−1 after 200 cycles at 0.2 C) was obtained by using the crosslinked network binder. The lithium insertion capacity of the silicon electrode was limited to 1000 mAh g−1, which can maintain 650 cycles. This reasonable design provides a way for the manufacture and practical application of high-performance silicon-based anodes.

Locust bean gum as green and water-soluble binder for LiFePO4 and Li4Ti5O12 electrodes

Locust Bean Gum (LBG, carob bean gum) was investigated as an environmentally friendly, natural, and water-soluble binder for cathode (LFP) and anode (LTO) in lithium-ion batteries (Li-ion). For the first time, we show LBG as an electrode binder and compare to those of the most popular aqueous (CMC) and conventional (PVDF) binders. The electrodes were characterized using TGA/DSC, the galvanostatic charge–discharge cycle test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Thermal decomposition of LBG is seen to begin above 250 °C with a weight loss of about 60 wt% observed at 300 °C, which is sufficient to ensure stable performance of the electrode in a Li-ion battery. For CMC, weight loss at the same temperature is about 45%. Scanning electron microscopy (SEM) shows that the LFP–LBG system has a similar distribution of conductive carbon black particles to PVDF electrodes. The LTO–LBG electrode has a homogeneous dispersion of the electrode elements and maintains the electrical integrity of the network even after cycling, which leads to fast electron migration between LTO and carbon black particles, as well as ion conductivity between LTO active material and electrolyte, better than in systems with CMC and PVDF. The exchange current density, obtained from impedance spectroscopy fell within a broad range between 10−4 and 10−2 mA cm−2 for the LTO|Li and LFP|Li systems, respectively. The results presented in this paper indicate that LBG is a new promising material to serve as a binder.Graphic abstract

Biomass-derived fluorinated corn starch emulsion as binder for silicon and silicon oxide based anodes in lithium-ion batteries

In this work, an in situ crosslinked network is prepared as the binder of silicon (Si), Si-graphite and silicon oxide (SiO)-graphite anodes. Fluorinated hydrolyzed corn starch synthesized by emulsifier-free polymerization is mixed with equal corn starch and 0.1 mg mL−1 dopamine, consequently form reversible interactions with electrode particles and copper foil, which plays a vital role in maintaining electrode structural integrity. It is found that the electrochemical performances of Si electrodes are heavily influenced by fluorinated carbon atoms and space linker groups of perfluoroalkyl side chains in polymeric binder. Binder with poly(N-methylperfluorobutane-1-sulfonamide ethyl acrylate) side chains (SSC4SA) exhibits the best performance, which realizes an initial discharge capacity of 3801 mAh g−1 and 88.0% capacity retention at 1 A g−1 after 100 cycles. Si-graphite and SiO–graphite composite electrodes with the mass ratio of 15:73 are prepared applying SSC4SA binder. The capacity retention of composite electrodes are 58.7% and 95.6% after 200 and 500 cycles respectively, which are far superior to commercial carboxyl methyl cellulose-styrene butadiene rubber (CMC-SBR) binder based electrodes. Such simply preparation method and the understanding of design principles for silicon anode binders in molecular-level are useful for further fundamental researches and practical applications.

A self-healable polymer binder for Si anodes based on reversible Diels–Alder chemistry

Polymeric binders that interact strongly with Si can overcome a rapid capacity fading caused by its large volumetric changes (around 400%) during the charge-discharge process when Si was used as a next generation anode material in lithium ion batteries (LIBs). Among them, poly(acrylic acid) (PAA) is known to improve cell cyclability by enhancing the mechanical properties of Si through hydrogen bonding. This study added 1,6-bismaleimide (BMI) as a crosslinker to furfurylamine-functionalized poly(acrylic acid) (FPAA) and formed a 3D crosslinked polymer network based on thermal Diels–Alder (D–A) click chemistry, which was then used as a new polymer binder for the Si anode. Having the reversible nature of D–A chemistry, the crosslinked network exhibited a self-healing property. The Si electrode with the D-A-adduct binder (DA-PAA) had excellent adhesive strength with regards to Si. After 200 cycles, it recorded a reversible capacity of 1076 mAh g−1 and a high Coulombic efficiency of 99.7%, both of which were much higher than the values obtained for typical commercial binders.

Effects of water‐based binders on electrochemical performance of manganese dioxide cathode in mild aqueous zinc batteries

AbstractIn the majority of rechargeable batteries including lithium‐ion batteries, polyvinylidene fluoride (PVdF) binders are the most commonly used binder for both anode and cathode. However, using PVdF binder requires the organic solvent of N‐methyl‐2‐pyrrolidone which is expensive, volatile, combustible, toxic, and has poor recyclability. Therefore, switching to aqueous electrode processing routes with non‐toxic binders would provide a great leap forward towards the realization of ideally fully sustainable and environmentally friendly electrochemical energy storage devices. Various water‐soluble binders (aqueous binders) were characterized and compared to the performance of conventional PVdF. Our study demonstrates that the electrochemical performance of Zn/MnO2 aqueous batteries is significantly improved by using sodium carboxymethyl cellulose (CMC) binder. In addition, CMC binders offer desirable adhesion, good wettability, homogeneous material distribution, and strong chemical stability at certain pH levels (3.5–5) without any decomposition for long‐cycle life.

Partially lithiated ternary graft copolymer with enhanced elasticity as aqueous binder for Si anode

AbstractPartially lithiated ternary graft copolymers were synthesized through free radical graft polymerization of acrylic acid (AA), lithium acrylate (LiAA) and hydroxyethyl acrylate (HEA) onto polyvinyl alcohol (PVA). With optimized feeding molar ratio of AA/LiAA/HEA (2:1:2), the ternary graft copolymer with partial lithiation shows the best flexibility, elasticity and adhesion strength comparing to PVA‐g‐PAA and PVA‐g‐P(AA‐HEA) when used as aqueous binder for Si anode. The Si anode using PVA‐g‐P(AA‐LiAA‐HEA) with the optimized molar ratio of AA‐LiAA‐HEA exhibits better cycling stability and rate performance, delivering a capacity of 2265 mAh g−1 with a capacity retention of 82.4% after 200 cycles at 1A g−1. Even at a high current of 10 A g−1, the Si electrode still obtained a high capacity of 1300 mAh g−1.

Synthesis of Carboxymethyl Cellulose Form Banana Stems and its Characterization for Anode Binder of Li-Ion Battery

Banana (Musa acuminate) is one of the important fruit crop cultivated in Indonesia. Banana stems is waste biomass form banana farming which the amount is very abundant. Recently, the banana stems waste was used for animal feed, but the amount is small, mostly goes as waste. Banana stems have a high cellulose and hemicellulose content, more than 60%, which made it useful for row material of Carboxymethyl Cellulose (CMC). In this paper, we synthesized CMC from banana stems and apply it as binder in the electrodes of lithium ion battery. The steps of synthesizing CMC from banana stems started with the isolation of the cellulose, then followed by the processes of alkalization, carboxymethylation and finally the purification. FTIR spectrum shows the absorption bands at 3427 cm-1, 2928 cm-1, 1613 cm-1 and 1420 cm-1 which indicated the successfully of CMC synthesized. The presence of strong absorption bands at 1613 cm-1 and 1420 cm-1 are related to the stretching vibration of the carboxyl group (COO-) and (COO-Na). The peak absorption at around 2928 cm-1 is due to stretching vibration of all hydrocarbon constituent in CMC. While the broad absorption around 3427 cm-1 is due to the stretching vibration of the hydroxyl groups (-OH). The purity test of CMC mesh-100 is resulting the purity values of 99.84%. These results prove that CMS has actually been formed with high purity. In the application of CMC as anode binder, the best composition is 3 % CMC, where it gives the highest conductivity of 0.457 S/cm. Voltammogram cyclic measurement with a scan rate of 50 mV/s in the voltage range of -1.2 to 1.2 Volt gives the capacitance value of 18 mF.

Interconnected conductive gel binder for high capacity silicon anode for Li-ion batteries

A new design for conjugation and crosslinking combined with a conjugated polymer and its application for high capacity Li-ion battery are demonstrated. Polyfluorene (PF), poly(phenylene) (PP), with lateral substituents, namely carboxylic acids, as a potential building block for conjugation was synthesized and characterized. The synthesis was achieved through Suzuki polycondensation reaction in the presence of Pd(PPh3)4 catalyst by using dibromo benzoic acid in conjunction with dioctylfluorene-diboronic acid bis(1,3-propanediol) ester. Thermal chemical cross-linking between carboxylic acid in the polymer backbone and free hydroxyl groups in poly(vinyl alcohol) (PVA) has been performed in the presence of Si. This approach enables a polymer binder with multi-functionality providing a high electronic conductivity and good cycling stability. Overall, we report on a Si-anode with capacity of 1932 mAh/g at C/3, demonstrating the improvement of the electrode using gel polymer binder.

Synthesis of silicon anode binders with ultra-high content of catechol groups and the effect of molecular weight on battery performance

Highly adhesive binders are developed to prolong the cycle life of silicon anodes and accelerate their practical application. A series of poly(N-methacryloyl-3,4-dihydroxy-l-phenylalanine) (PMDOPA) binders, containing ultra-high content of catechol groups, are synthesized through radical polymerization and applied to silicon anodes. The ultra-high content of catechol groups endows the PMDOPA binder superior adhesive strength compared to the carboxyl groups of the polyacrylic acid (PAA) binder. As the molecular weight increases, the flexibility, solvent resistance and adhesive strength of the PMDOPA binders are all enhanced, which effectively alleviates the electrode pulverization during long-term cycling and prolongs the cycle life of batteries. Especially, the PMDOPA-20 binder, which possesses the highest molecular weight of 208 kDa among all the PMDOPA samples, exhibits the longest cycle life of 665 cycles at the current density of 840 mA g−1, even though its molecular weight is lower than PAA. This work demonstrates that both the functional adhesive group and molecular weight are crucial for binder performance, which provides a valuable reference for the future development of high-performance binders.

Ultra-efficient polymer binder for silicon anode in high-capacity lithium-ion batteries

As a highly promising anode material for high-capacity lithium-ion batteries (LIBs), the low electronic conductivity and large volume variation of silicon (Si) make the slurry-coating Si based electrode requiring high content of “inert” materials and suffering rapid capacity fading. Herein, a polyimine, synthesized via one-step condensation reaction, has been demonstrated as an ultra-efficient polymer binder that can resolve the above issues. The polyimine binder containing Si electrode delivers superior electrochemical performance: a delithiation specific capacity of 804.4 mAh g −1 with capacity retention of 82.4% after 1000 cycles at the current density of 2 A g −1 . The high efficiency of polyimine binder for Si electrode has also been demonstrated with ultrahigh weight ratio of “active” material to “inert” material (R A/I ). The electrode with 95 wt% of Si (95Si/Polyimine, R A/I = 19) reveals a reversible delithiation capacity of 2114 mAh g −1 (capacity retention ~ 80.4%) over 200 cycles at the current density of 400 mA g −1 . Even at the high current density of 2 A g −1 , a delithiation capacity of 1087.8 mAh g −1 after 500 cycles can be obtained. Molecular simulations and atomic force microscopy (AFM) indentation are utilized to investigate the ultra-efficiency of polyimine binder. With simple manufacturing process and ultra-efficient binder performance, the designed polyimine binder will be definitely meaningful in achieving low-cost and high-capacity LIBs with prolonged cycle life. An ultra-efficient polymer binder enables the slurry-coated Si electrode with unprecedented highest weight ratio of “active” materials to “inert” materials (R A/I ) and prolonged cycle life is reported. Traditional Si based electrodes always require high content of “inert” materials and suffer rapid capacity fading. A polyimine, synthesized via one-step condensation reaction, can efficiently resolve the above issues, and the electrochemical performance of Si electrodes can be significantly improved using a small amount of polyimine binder. Molecular simulations and atomic force microscopy (AFM) indentation are utilized to investigate the ultra-efficiency of polyimine binder, and the current design will be useful in achieving the Si (or Si composite) electrodes with high cost efficiency and long cycle life. • An ultra-effcient polymer binder for high-performance Si anode. • Silicon electrode with unprecedented highest weight ratio of “active/inert” materials. • Significantly improved binder performance than state-of-art binders. • Towards a cost-efficient process and energy-efficient battery via developed polyimine binder.

Ion-Cross-Linking-Promoted High-Performance Si/PEDOT:PSS Electrodes: The Importance of Cations’ Ionic Potential and Softness Parameters

PSS has been studied as a silicon-based binder due to its inherent superior electricity and electrochemical stability. However, it cannot effectively alleviate the huge volume changes of silicon during lithiation/delithiation due to its linear structure, resulting in poor cycling stability. Ion-cross-linking is a usual method to cross-link linear polymers into 3D structures. In this paper, multivalent cations of the 5th period and Group 2 cross-linked PEDOT:PSS were applied as silicon anode binders and studied systematically. It was found that the variation trend of viscosity and conductivity of PEDOT:PSS after cross-linking was consistent with that of ionic potential and softness parameters of multivalent cations. The mesostructure of a binder after cross-linking is influenced by the solubility product constant of sulfites or hydroxides of cations and the growth characteristics of crystals. An Sn4+-cross-linked binder displayed increased viscosity and electrical conductivity and higher reduced modulus and hardness due to its positive softness parameter and higher ion potential. The Si electrode with the Sn4+-cross-linked binder showed improved cycling stability (1876.4 mAh g-1 compared with 1068.4 mAh g-1 of the electrode with the pure PEDOT:PSS binder after 100 cycles) and superior rate capability (∼800 mAh g-1 at an ultrahigh current density of 8.0 A g-1).

In Ukrainian

Replacing intercalated graphite in traditional lithium-ion batteries with conversion anode material gives an advantage in increasing specific energy at a lower price. A significant drawback of is its very large swelling when saturated with lithium, with the growth of mechanical loads in the bulk of the electrode layer. Direct use of silicon, even nanoscale, is impossible without modifying the interface of the silicon | A stable cycling is shown of electrodes based on the nanocomposite Si@SiOC&C (0D E micro-3D) with a high content (9nano-S@1SiOC&C by mass), active electrically conducting additive of synthetic graphite KS6 and vinylidene fluoride polymer binder in traditional ethylene carbonate electrolyte. The effect is discussed of carbon-enriched oxycarbide (glass-like carbon) – SiOC&C, as a modifier of the silicon | interface, synthesized using polymethylphenylsiloxane, on their electrochemical behavior. Formation of structurally-integrated phase boundary in the synthesis of the composite, the high mechanical strength of the glass-like carbon, the capability of SiOC&C to set up a relatively large amount of lithium in its bulk and a low electrocatalytic activity of this material in relation to organic electrolyte allows to accommodate without cracking the volume changes of silicon, solving the problem of preventing destruction carbon coating of active nanoparticles during long-term cycles of electrodes. Glass-like carbon material can also contribute to the phase transition of the cubic α-Li 15 Si 4 , with the formation of which the volume of the original increases by 280 %, to a denser ortorombic β-Li 15 Si 4 , with a smaller increase in volume (by 210 %). Therefore, the usual vinylidene fluoride polymer binder for graphite anode of lithium-ion batteries can provide effective electrical contact between the particles of the active material and the current collector. These electrodes are effective for use in high-energy lithium-ion superbatteries.

Spider silk binder for Si-based anode in lithium-ion batteries

Silicon (Si) has attracted attention for use in lithium ion batteries due to its high theoretical capacity and its natural abundance. However, significant change in the volume of Si electrodes during repeated cycles causes dramatic capacity degradation and reduces the benefits of its attractive qualities. Here, it is reported for the first time that a derivative of natural spider silk is effective for retaining the capacity and decreasing the volume expansion of Si for use in Li-ion batteries as electrodes. Relative to the Si-electrode with polyvinylidene fluoride (SPVDF), the Si-electrode containing binder with the dissolved spider silk (SWS) cells achieved significant enhanced capacities with cycling stability during repeated cycles. The SWS electrode at 250 mA g −1 showed the discharge/charge capacities of 3642/1938 mAh g−1 at 1st cycle, 1789/1541 mAh g−1 at 2nd cycle and then reduced to 1142/1054 mAh g−1 at the 5th cycle. However, the capacities of the SPVDF electrode were 3903/2694 mAh g−1, 1455/1211 mAh g−1, and 458/435 mAh g−1. Furthermore, the discharge capacity of SWS was 333 mAh g−1 at the 38th cycle, but that of SPVDF showed 323 mAh g−1 at the 7th cycle. Such superior performance with good cycling ability may be attributed to the unique properties of spider silk: the folded crystal layer with semi-amorphous structure, the superior properties of viscosity and adhesion, and the close stacking by the protein blocks as well as the side chain R-group of crystal β-sheet. The combination of these characteristics was able to restrain the deleterious change in the volume of Si materials substantially, and to provide superior electrochemical characteristics of lithium ions.

Allylimidazolium-Based Poly(ionic liquid) Anodic Binder for Lithium-Ion Batteries with Enhanced Cyclability

An allylimidazolium-based poly(ionic liquid), poly[vinylbenzylallylimidazolium bis(trifluoromethane)sulfonylimide] (PVBCAImTFSI) was used as a binder for graphite anodes in lithium-ion batteries. T...

Microporous Binder for the Silicon-Based Lithium-Ion Battery Anode with Exceptional Rate Capability and Improved Cyclic Performance.

Silicon anodes have attracted much attention owing to their high theoretical capacity. Nonetheless, an inevitable and enormous volumetric expansion of silicon in the lithiated state restrained the development of the silicon anode for lithium-ion batteries. Fortunately, the utilization of the high-performance binder is a promising and effective way to overcome such obstacles. Herein, a polymer of intrinsic microporosity (PIM) is applied as the binder for the silicon anode, which is composed of a rigid polymer backbone, an intrinsic porous structure, and active carboxyl groups (PIM-COOH). Compared to the traditional binder, both the long-term stability and rate performance of the electrode using PIM-COOH as the binder are significantly improved. The mechanism responsible for the enhanced performance is investigated. The PIM-COOH binder provides stronger adhesion toward the current collector than the conventional binders. The unique rigid polymer backbone and porous structure of the PIM-COOH binder enable a good capability to withstand the volume change and external stress generated by the Si anode. The porous structure of the PIM-COOH binder enhances lithium-ion transportation compared to the SA binder, which improves rate performance of the silicon anode. This work provides a unique insight into design, synthesis, and utilization of the binders for lithium-ion batteries.