Experimental study on the mechanical and electrochemical properties of aqueous emulsifiable diphenylmethane diisocyanate-modified silicon-carbon composite electrodes.

Aqueous emulsifiable diphenylmethane diisocyanate (EMDI) can form strong chemical bonds with aqueous adhesives due to the large number of isocyanate (-NCO) groups, which can enhance the mechanical performance of the adhesives. Currently, sodium carboxymethyl cellulose (CMC)-styrene butadiene rubber (SBR) emulsion aqueous bonding agents are widely used in the preparation of anode materials for lithium-ion batteries (LIBs). In this study, EMDI was added to a porous silicon-carbon composite electrode prepared from CMC-SBR, and the evolution of the mechanical properties of the electrode with the EMDI content was first investigated quasi-static uniaxial tensile and interfacial strength tests.

Oxidized Starch-Reinforced Aqueous Polymer Isocyanate Cured with High-Frequency Heating.

In this research, an oxidized starch/styrene-butadiene rubber system with high capability of absorbing electromagnetic energy was adopted as the main component, the effect of oxidized starch content on the bonding and mechanical properties of aqueous polymer isocyanate (API) after high-frequency curing was evaluated, and the effect mechanisms were explored by combining thermodynamic tests and material characterization methods. Our findings revealed that the addition of oxidized starch enhanced the mechanical properties of API after high-frequency curing and the increase in the amount of oxidized starch enhanced the improvement effect of high-frequency curing on API bonding and mechanical properties. At 5 wt% oxidized starch, high-frequency curing improved API bonding properties by 18.

Investigation on the mechanical integrity of a PEO-based polymer electrolyte in all-solid-state lithium batteries.

Polyethylene oxide (PEO)-based solid polymer electrolytes (SPEs) have good ionic conductivity and flexibility, and is a key component of all-solid-state lithium batteries (ASSLBs). Therefore, the mechanical integrity of PEO-based SPEs during cell operation needs to be urgently evaluated. Here, we conducted a series of tensile and shear adhesion performance tests on PEO-LiTFSI electrolyte and LiFePO electrode adhesion samples at various temperatures and quenching rates.

Enhancing the ionic conductivity and mechanical properties of PEO-based solid electrolytes through thermal pre-stretching treatment.

Pre-stretching as a method for directing polymer crystallization offers a promising solution for addressing the limitations of solid polymer electrolytes in flexible batteries at ambient temperatures. In this study, we have investigated the ionic conductivity, mechanical behaviour, and microstructural and thermal properties of polyethylene oxide (PEO)-based polymer electrolytes with varying pre-strain levels. The results indicate that thermal stretching-induced pre-deformation can significantly increase the through-plane ionic conductivity, in-plane strength, stiffness of solid electrolytes, and cell-specific capacity.

Modeling and Simulation in Capacity Degradation and Control of All-Solid-State Lithium Battery Based on Time-Aging Polymer Electrolyte.

The prediction of electrochemical performance is the basis for long-term service of all-solid-state-battery (ASSB) regarding the time-aging of solid polymer electrolytes. To get insight into the influence mechanism of electrolyte aging on cell fading, we have established a continuum model for quantitatively analyzing the capacity evolution of the lithium battery during the time-aging process. The simulations have unveiled the phenomenon of electrolyte-aging-induced capacity degradation.

Mechanical Integrity Degradation and Control of All-Solid-State Lithium Battery with Physical Aging Poly (Vinyl Alcohol)-Based Electrolyte.

Ensuring the material durability of an electrolyte is a prerequisite for the long-term service of all-solid-state batteries (ASSBs). Herein, to investigate the mechanical integrity of a solid polymer electrolyte (SPE) in an ASSB upon electrochemical operation, we have implemented a sequence of quasi-static uniaxial tension and stress relaxation tests on a lithium perchlorate-doped poly (vinyl alcohol) electrolyte, and then discussed the viscoelastic behavior as well as the strength of SPE film during the physical aging process. On this basis, a continuum electrochemical-mechanical model is established to evaluate the stress evolution and mechanical detriment of aging electrolytes in an ASSB at a discharge state.

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.

Towards a Deeper Understanding of Creep and Physical Aging Behavior of the Emulsion Polymer Isocyanate.

Information of the relaxation behaviors of polymer film is crucial to judge the durability of emulsion polymer isocyanate (EPI) as a structural adhesive for bonding timber-based products. A sequence of tensile creep tests and free volume evaluation of the cured EPI adhesive films during isothermal condition were carried out by dynamic mechanical analysis and positron annihilation lifetime spectroscopy, respectively. It is the first time to explore the creep response and physical aging of the EPI film, as well as associated microstructural evolution.

Effect of Conductive Carbon Black on Mechanical Properties of Aqueous Polymer Binders for Secondary Battery Electrode.

To predict the cyclic stability of secondary battery electrodes, the mechanical behaviors of polymer binders and conductive composites (BCC) is of great significance. In terms of uniaxial tension, tensile stress relaxation, and bonding strength tests, the present study encompasses a systematic investigation of the mechanical properties of two typical aqueous binders with different contents of Super-S carbon black (SS) under a liquid electrolyte. Meanwhile, the microstructure of cured film and the surface morphology of the bonding interface are investigated in detail.

Revealing the Mechanical Properties of Emulsion Polymer Isocyanate Film in Humid Environments.

Knowledge of the mechanical behaviors of polymer film in humid environments is of great significance for predicting the long-term performance of emulsion polymer isocyanate (EPI) as a high-performance wood adhesive. A tri-copolymer latex was cross-linked by the general polymeric methylene diisocyanate (-MDI) and aqueous emulsified isocyanate (EMDI) at different loadings for preparing EPI. Furthermore, a series of uniaxial tension tests under different relative humidity (RH) were carried out on cured EPI samples before and after post-curing treatment, and the corresponding chemical structure, as well as the microstructure of polymers, was investigated in detail.

A Coupled Thermodynamic Model for Transport Properties of Thin Films during Physical Aging.

A coupled diffusion model based on continuum thermodynamics is developed to quantitatively describe the transport properties of glassy thin films during physical aging. The coupled field equations are then embodied and applied to simulate the transport behaviors of O₂ and CO₂ within aging polymeric membranes to validate the model and demonstrate the coupling phenomenon, respectively. It is found that due to the introduction of the concentration gradient, the proposed direct calculating method on permeability can produce relatively better consistency with the experimental results for various film thicknesses.

Analysis of lithium ion concentration and stress in the solid electrolyte interphase on the graphite anode.

One of the critical challenges in advancing lithium ion battery performance is increasing mechanical stability of the solid electrolyte interphase (SEI) layers. Our work aims at developing a mathematical model to study the lithium ion concentration and stress in the SEI on the graphite anode. The main influence factors on the SEI stress have been thoroughly investigated.

Relaxation of a hydrophilic polymer induced by moisture desorption through the glass transition.

Regarding the underlying special relaxation feature of a water-plasticized hydrophilic polymer during performance evolution with water content change, we report the water desorption kinetics and periodic creep responses of poly(vinyl alcohol) (PVA) films subsequent to rejuvenation by above-glass transition relative humidity (RH) annealing and following RH-jump at various rates. A Moisture Sorption Analyzer and a Dynamic Mechanical Analyzer are utilized to control RH and to capture data to probe the evolving relaxation towards equilibrium under two temperature-RH conditions. This result reveals an evident jump rate dependence of desorption kinetics and recoverable creep deformation.