Inorganic crosslinked supramolecular binder with fast Self-Healing for high performance silicon based anodes in Lithium-Ion batteries

Novel strategies for constructing highly efficient silicon/carbon anodes: Chemical prelithiation and electrolyte post-treatment

Chemical prelithiation is an effective method to compensate for the loss of active lithium due to the formation of solid electrolyte interface, effectively addressing the issue of low initial coulombic efficiency (ICE) in silicon/carbon (Si/C) materials. Herein, the Si/C anode is prelithiated in a 1 M lithium-phenanthrene/2-methyltetrahydrofuran (Li-Phe/2-MTHF) solution in our work, and the prelithiated Si/C anode is followed by post-treatment with commercial electrolytes containing lithium difluorobis(oxalato)phosphate (LiDFBOP). The PSi/C-L0.5, originated from the reaction between residual Li-Phe/2-MTHF and the commercial electrolyte containing 0.5 wt% LiDFBOP, possesses the artificial SEI film, which not only contains a proper amount of LiF but also is rich in Li2C2O4 and Li3P. Among them, LiF and Li2C2O4 ensures the stability of the SEI film. Simultaneously, the synergistic effect of Li3P and LiF improves its Li+ transport kinetics. Therefore, the ICE of PSi/C-L0.5 reaches 92.50 %, and almost no drop in capacity occurs after 100 cycles at 0.5 A/g. Furthermore, the capacity stays steady at about 270 mAh/g through nearly 500 cycles at 1 A/g, achieving an impressive capacity retention rate of 97.8 %, significantly outperforming un-treated Si/C. This study offers new directions for constructing SEI films with stable structures and high Li+ kinetics transport.

A Tough and Self-Healable Semi-IPN Hydrogel Binder Based on Multiple Dynamic Bonds for Si Anodes in Lithium-Ion Batteries

In recent years, hydrogels have garnered significant attention as potential binders for silicon (Si) anodes in lithium-ion batteries (LIBs), owing to their elasticity, flexibility, and adhesion properties that accommodate the substantial volume changes characteristic of Si during charge-discharge cycles. In addition, their environmental benefits are further amplified by using water as a solvent. Despite their promising attributes, conventional hydrogels frequently exhibit insufficient mechanical robustness, making them susceptible to structural degradation under the demanding conditions of battery operation. Herein, we developed a semi-interpenetrating polymer network (semi-IPN) hydrogel. By incorporating multiple dynamic bonds into the network, we achieved balanced properties between the self-healing ability and mechanical strength. This hydrogel was fabricated by combining the network of acrylic acid (AAc) cross-linked with B-N coordinated boronic ester bonds bearing a cross-linker (N-BE cross-linker) and the network of carboxymethyl cellulose (CMC). Further, metal coordination bonds between Al3+ and the skeleton of the hydrogel give robust mechanical strength and adhesion properties. The prepared hydrogel binder effectively mitigates Si's bulk expansion and promotes a more stable solid electrolyte interphase (SEI) during extended cycling, owing to the 3D structure of the hydrogel network and abundance of functional groups capable of forming hydrogen bonds with the Si anode surface. Si anodes utilizing this composite binder exhibit a reversible specific capacity of 1023.8 mAh g-1 after 300 cycles at 0.2 C, significantly outperforming conventional PVDF-binder anodes which remain only 308.3 mAh g-1 under identical conditions. This improvement in capacity retention demonstrates the superior performance of the semi-IPN hydrogel binder for Si anodes in LIBs.

Advances and future perspectives on silicon-based anodes for lithium-ion batteries

Silicon (Si)-based anode has emerged as the most promising anode material for next-generation lithium-ion batteries (LIBs) due to its high specific capacity, suitable operating potential and abundant natural reserves. Nevertheless, the drastic volume effect of Si particles during lithiation/delithiation leads to particle pulverization, electrode structure collapse, and solid electrolyte interfacial (SEI) film instability, which results in a rapid reversible capacity degradation of Si-based anodes. It is essential to deeply analyze the failure mechanism of silicon-based electrodes and explore suitable improvement methods to achieve higher capacity retention. Herein, we systematically summarize the improvement strategies for Si-based anodes, including regulating material particle size, optimizing structure and composition, and exploring new binders, along with their enhancement mechanisms. In addition, the preparation of high-performance Si-based electrodes based on newly developed 3D printing technology in recent years is discussed. Lastly, several possible directions and emerging challenges for Si anode are presented to facilitate further improvement in practical applications. Overall, this review is expected to provide basic understanding and insights into the practical application of Si-based materials in next-generation LIBs negative electrodes.

The Structural Effect of a Composite Solid Electrolyte on Electrochemical Performance and Fire Safety

In this study, we investigated the structural effect of composite solid electrolytes of Al-doped LLZO and PVDF-HFP (0D_Al-LLZO@PVDF-HFP and 1D_Al-LLZO@PVDF-HFP) on electrochemical (EC) performance and fire safety through a systematic evaluation and comparative tests. The unique structure and advantageous features of composite solid electrolytes (1D_Al-LLZO@PVDF-HFP) were highlighted by comparing controls (PVDF-HFP and 0D_Al-LLZO@PVDF-HFP) with physicochemical and electrochemical analyses and fire safety tests The structure and morphology of Al-doped LLZO/PVDF-HFP composites were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM), while their chemical functionalities and free ion clusters were examined with Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, respectively. The 1D_Al-LLZO@PVDF-HFP composite with a 1D structured Al-LLZO filler network in the PVDF-HFP matrix could effectively regulate the crystallinity of PVDF-HFP and facilitated lithium salt dissociation, resulting in a high lithium-ion transference number and ionic conductivity. As a result, the 1D_Al-LLZO@PVDF-HFP composite electrolyte with an optimized structure and low Al-LLZO content (~5.1 wt%) exhibited enhanced ionic conductivity (σ: 1.40 × 10-4 S/cm) with low interfacial resistance, broadened EC stability (voltage window: 4.75 V vs. Li/Li+), and a high lithium-ion transference number (0.75) superior to that of 0D_Al-LLZO@PVDF-HFP. In electrochemical characterizations, the 1D_Al-LLZO@PVDF-HFP-based EC cell demonstrated enhanced performance in a lithium symmetric cell (>2000 h) and full cell (LiFePO4|electrolyte|Li) of a reversible capacity of 102.7 mAh/g at 2C with a capacity retention of 85.7% over 200 cycles, better than that of a 0D_ Al-LLZO@PVDF-HFP-based EC cell. In flammability tests, Al-LLZO@PVDF-HFP demonstrated enhanced fire safety (nonflammability) compared with that of a PVDF-HFP-based electrolyte regardless of the composite structure, suggesting the importance of inorganic filler rather than their structural morphology in the composite.

Damage-Tolerant and Self-Repairing Web-Like Borate Type Binder Enable Stable Operation of Efficient Si-Based Anodes

Novel binder designs are shown to be fruitful in improving the electrochemical performance of silicon (Si)-based anodes. However, issues with mechanical damage from dramatic volume change and poor lithium-ion (Li+) diffusion kinetics in Si-based materials still need to be addressed. Herein, an aqueous self-repairing borate-type binder (SBG) with a web-like architecture and high ionic conductivity is designed for Si and SiO electrodes. The 3D web-like architecture of the SBG binder enables uniform stress distribution, while its self-repairing ability promotes effective stress dissipation and mechanical damage repair, thereby enhancing the damage tolerance of the electrode. The tetracoordinate boron ions (- BO 4 - $ - {\mathrm{BO}}_4^ - $ ) in the SBG binder boosts the Li transportation kinetics of Si-based electrodes. Based on dynamic covalent and ionic conductive boronic ester bonds, the diverse requirements of the binder, including uniform stress distribution, self-repairing ability, and high ionic conductivity, can be met by simple components. Consequently, the proposed straightforward multifunction design strategy for binders based on dynamic boron chemistry provides valuable insights into fabricating high-performance Si-based anodes.

A Robust Network Sodium Carboxymethyl Cellulose-Epichlorohydrin Binder for Silicon Anodes in Lithium-Ion Batteries

Silicon (Si), as an ideal anode component for lithium-ion batteries, is susceptible to substantial volume changes, leading to pulverization and excessive electrolyte consumption, ultimately resulting in a rapid decline in the cycle stability. Herein, a new sodium carboxymethyl cellulose-epichlorohydrin (CMC-ECH) binder featuring a three-dimensional (3D) network cross-linked structure is synthesized by a simple ring-opening reaction, which can effectively bond the Si anode through abundant covalent and hydrogen bonds to mitigate its pulverization. Benefitting from the merits of the CMC-ECH binder, the electrochemical performance is significantly enhanced compared to the CMC binder. The CMC-ECH binder is applied to Si anodes, a specific capacity of 1054.2 mAh g-1 can be maintained at 0.2 C following 200 cycles under an elevated Si mass loading of around 1.0 mg cm-2, and the corresponding capacity retention is 65.6%. In the case of the LiFePO4//Si@CMC-ECH full battery, the cycle stability exhibits a substantial enhancement compared with the LiFePO4//Si@CMC full battery. Furthermore, the CMC-ECH binder demonstrates compatibility with micron-Si anode materials. Based on the above, we have successfully developed a facilely prepared water-based CMC-ECH binder that is suitable for Si and micron-Si anodes in lithium-ion batteries.

Achievements, challenges, and perspectives in the design of polymer binders for advanced lithium-ion batteries

Energy storage devices with high power and energy density are in demand owing to the rapidly growing population, and lithium-ion batteries (LIBs) are promising rechargeable energy storage devices. However, there are many issues associated with the development of electrode materials with a high theoretical capacity, which need to be addressed before their commercialization. Extensive research has focused on the modification and structural design of electrode materials, which are usually expensive and sophisticated. Besides, polymer binders are pivotal components for maintaining the structural integrity and stability of electrodes in LIBs. Polyvinylidene difluoride (PVDF) is a commercial binder with superior electrochemical stability, but its poor adhesion, insufficient mechanical properties, and low electronic and ionic conductivity hinder its wide application as a high-capacity electrode material. In this review, we highlight the recent progress in developing different polymeric materials (based on natural polymers and synthetic non-conductive and electronically conductive polymers) as binders for the anodes and cathodes in LIBs. The influence of the mechanical, adhesion, and self-healing properties as well as electronic and ionic conductivity of polymers on the capacity, capacity retention, rate performance and cycling life of batteries is discussed. Firstly, we analyze the failure mechanisms of binders based on the operation principle of lithium-ion batteries, introducing two models of "interface failure" and "degradation failure". More importantly, we propose several binder parameters applicable to most lithium-ion batteries and systematically consider and summarize the relationships between the chemical structure and properties of the binder at the molecular level. Subsequently, we select silicon and sulfur active electrode materials as examples to discuss the design principles of the binder from a molecular structure point of view. Finally, we present our perspectives on the development directions of binders for next-generation high-energy-density lithium-ion batteries. We hope that this review will guide researchers in the further design of novel efficient binders for lithium-ion batteries at the molecular level, especially for high energy density electrode materials.

Bio-Inspired Electrodes with Rational Spatiotemporal Management for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are currently the predominant energy storage power source. However, the urgent issues of enhancing electrochemical performance, prolonging lifetime, preventing thermal runaway-caused fires, and intelligent application are obstacles to their applications. Herein, bio-inspired electrodes owning spatiotemporal management of self-healing, fast ion transport, fire-extinguishing, thermoresponsive switching, recycling, and flexibility are overviewed comprehensively, showing great promising potentials in practical application due to the significantly enhanced durability and thermal safety of LIBs. Taking advantage of the self-healing core-shell structures, binders, capsules, or liquid metal alloys, these electrodes can maintain the mechanical integrity during the lithiation-delithiation cycling. After the incorporation of fire-extinguishing binders, current collectors, or capsules, flame retardants can be released spatiotemporally during thermal runaway to ensure safety. Thermoresponsive switching electrodes are also constructed though adding thermally responsive components, which can rapidly switch LIB off under abnormal conditions and resume their functions quickly when normal operating conditions return. Finally, the challenges of bio-inspired electrode designs are presented to optimize the spatiotemporal management of LIBs. It is anticipated that the proposed electrodes with spatiotemporal management will not only promote industrial application, but also strengthen the fundamental research of bionics in energy storage.

Boron-doped three-dimensional porous carbon framework/carbon shell encapsulated silicon composites for high-performance lithium-ion battery anodes

Deleterious volumetric expansion and poor electrical conductivity seriously hinder the application of Si-based anode materials in lithium-ion batteries (LIBs). Herein, boron-doped three-dimensional (3D) porous carbon framework/carbon shell encapsulated silicon (B-3DCF/Si@C) hybrid composites are successfully prepared by two coating and thermal treatment processes. The presence of 3D porous carbon skeleton and carbon shell effectively improves the mechanical properties of the B-3DCF/Si@C electrode during the cycling process, ensures the stability of the electrical contacts of the silicon particles and stabilizes the solid electrolyte interface (SEI) layer, thus enhancing the electronic conductivity and ion migration efficiency of the anode. The developed B-3DCF/Si@C anode has a high reversible capacity, excellent cycling stability and outstanding rate performance. A reversible capacity of 1288.5 mAh/g is maintained after 600 cycles at a current density of 400 mA g-1. The improved electrochemical performance is demonstrated in a full cell using a LiFePO4-based cathode. This study presents a novel approach that not only mitigates the large volume expansion effects in LIB anode materials, but also provides a reference model for the preparation of porous composites with various functionalities.

Novel Binder with Cross-Linking Reconfiguration Functionality for Silicon Anodes of Lithium-Ion Batteries

Silicon is expected to be used as a high theoretical capacity anode material in lithium-ion batteries with high energy densities. However, the huge volume change incurred when silicon de-embeds lithium ions, leading to destruction of the electrode structure and a rapid reduction in battery capacity. Although binders play a key role in maintaining the stability of the electrode structure, commonly used binders cannot withstand the large volume expansion of the silicon. To alleviate this problem, we propose a PGC cross-linking reconfiguration binder based on poly(acrylic acid) (PAA), gelatin (GN), and β-cyclodextrin (β-CD). Within PGC, PAA supports the main chain and provides a large number of carboxyl groups (-COOH), GN provides rich carboxyl and amide groups that can form a cross-linking network with PAA, and β-CD offers rich hydroxyl groups and a cone-shaped hollow ring structure that can alleviate stress accumulation in the polymer chain by forming a new dynamic cross-linking coordination conformation during stretching. In the half cell, the silicon negative prepared by the PGC binder exhibited a high specific capacity and capacity maintenance ratio, and the specific capacity of the silicon negative electrode prepared by the PGC binder is still 1809 mAh g-1 and the capacity maintenance ratio is 73.76% following 200 cycles at 2 A g-1 current density, indicating that PGC sufficiently maintains the silicon negative structure during the battery cycle. The PGC binder has a simple preparation method and good capacity retention ability, making it a potential reference for the further development of silicon negative electrodes.

Advanced inorganic lithium metasilicate binder for high-performance silicon anode

Silicon (Si) is considered a high-capacity anode material with potential for next-generation lithium-ion batteries. However, the commercial application of Si anode is seriously hindered by huge volume variation (>300%) and limited Li+ diffusion ability. Herein, lithium metasilicate (LS), a novel inorganic binder, was innovatively developed to accommodate these challenges. Favorable compatibility is observed between the LS binder and Si nanoparticles (SiNPs) due to the existence of Si element within the LS skeleton. The interaction of the LS binder and SiNPs leads to a strong adhesion effect, enhancing the cycling stability of Si anode. The Si electrode with the LS binder presented an average discharge capacity of 2123 mAh/g at 0.84 A/g after 100 cycles. Furthermore, the presence of the Li+ transport channel within the LS binder enhances Li+ diffusion ability within Si anode. As a result, the average discharge capacity reaches 663 mAh/g at 8.4 A/g. This work thus explored new inorganic binder design approaches for Si anode, contributing to the advancement of high-performance Si anode.

Rational design of hollow Ti2Nb10O29 nanospheres towards High-Performance pseudocapacitive Lithium-Ion storage

Ti2Nb10O29, as one of the most promising anode materials for lithium-ion batteries (LIBs), possesses excellent structural stability during lithiation/delithiation cycling and higher theoretical capacity. However, Ti2Nb10O29 faces some challenges, such as insufficient ion diffusion coefficient and poor electronic conductivity. To overcome these problems, this study investigates the effect of applying nanostructure engineering on Ti2Nb10O29 and the lithium storage behaviors. We successfully synthesized hollow Ti2Nb10O29 nanospheres (h-TNO NSs) via solvothermal method using phenolic resin nanospheres as the template. The effects of using a template or not and the annealing atmospheres on the microstructures of the as-prepared Ti2Nb10O29 are investigated. Different nanostructures (porous Ti2Nb10O29 nanoaggregates (p-TNO NAs) without a template and core-shelled Ti2Nb10O29@C nanospheres (cs-TNO@C NSs)) were formed through annealing in Ar. When examined as anodes for LIBs, the h-TNO NSs electrode with hollow spherical structure displayed a better lithium storage performance. Compared to its counterparts, p-TNO NAs and cs-TNO@C NSs, h-TNO NSs electrode exhibited a higher reversible capacity of 282.5 mAh g-1 at 1C, capacity retention of 79.5% (i.e., 224.6 mAh g-1) after 200 cycles, and a higher rate capacity of 173.1 mAh g-1 at 10C after 600 cycles. The excellent electrochemical performance of h-TNO NSs is attributed to the novel structure. The hollow nanospheres with cavities and thin shells not only exposed more active sites and improved ion diffusion, but also buffered the volume variation upon cycling and facilitated electrolyte penetration. This consequently enhanced the lithium storage performance of the electrode and its high pseudocapacitive contribution (90% at 1.0 mV s-1).

Cross-linked multifunctional binder in situ tuning solid electrolyte interface for silicon anodes in lithium ion batteries

Silicon is considered as the most promising anode material for high performance lithium-ion batteries due to its high theoretical specific capacity and low working potential. However, severe volume expansion problems existing during the process of (de)intercalation which seriously hinders its commercial progress. Binder can firmly adhere silicon and conductive agent to the current collector to maintain the integrity of the electrode structure, thereby effectively alleviating the silicon volume expansion and realizing lithium-ion batteries with high electrochemical performance. In this paper, citric acid (CA) and carboxymethyl cellulose (CMC) are adopted to construct a covalently crosslinked CA@CMC binder by an easy-to-scale-up esterification treatment. The Si@CA@CMC-1 electrode material shows an impressive initial coulombic efficiency (ICE) at 82.1% and after 510 cycles at 0.5 A/g, its specific capacity is still higher than commercial graphite. The excellent electrochemical performance of Si@CA@CMC-1 can be attributed to the ester bonds formed among CA@CMC binder and silicon particles. Importantly, by decoupling in situ EIS combining XPS at different cycles, it can be further proved that the CA@CMC binder can tune the component of SEI which provide a new-route to optimize the performance of silicon.

Expired milk powder emulsion-derived carbonaceous framework/Si composite as efficient anode for lithium-ion batteries

Anodes based on silicon/carbon composites promise their commercial prospects for next-generation lithium ion batteries owing to their merits of high specific capacity, enhanced ionic and electronic conductivity, and excellent compatibility. Herein, a series of carbonaceous framework/Si composites are designed and prepared by rational waste utilization. N, P codoped foam-like porous carbon/Si composites (FPC@Si) and N, P codoped carbon coated Si composites (NPC@Si) are fabricated by utilizing expired milk powder as a carbon source with facile treatment methods. The results indicate that the porous carbon skeleton and carbon shell can improve the conductivity of Si and stabilize the solid electrolyte interfaces to avoid direct contact between active material and electrolyte. Moreover, the influence of drastic volume expansion of Si on the anode can be efficiently alleviated during charge/discharge processes. Therefore, the Si/C composite electrodes present excellent long-term cycling stability and rate capability. The electrochemical performance shows that the reversible capacity of FPC@Si and NPC@Si can be respectively maintained at 587.3 and 731.2 mAh g-1 after 1000 charge/discharge cycles under 400 mA g-1. Most significantly, the optimized Si/C composite electrodes exhibit outstanding performance in the full cell tests, promising them great potential for practical applications. This study not only provides a valuable guidance for recycling of waste resources, but also supports a rational design strategy of advanced composite materials for high-performance energy storage devices.

Three-dimensionally multiple protected silicon anode toward ultrahigh areal capacity and stability

Silicon (Si) is considered as one of the most promising candidates for next-generation lithium-ion battery (LIB) anode due to its high theoretical capacity. However, the drastic volume change of Si anodes during lithiation/delithiation processes leads to rapid capacity fade. Herein, a three-dimensional Si anode with multiple protection strategy is proposed, including citric acid-modification of Si particles (CA@Si), GaInSn ternary liquid metal (LM) addition, and porous copper foam (CF) based electrode. The CA modified supports strong adhesive attraction of Si particles with binder and LM penetration maintains good electrical contact of the composite. The CF substrate constructs a stable hierarchical conductive framework, which could accommodate the volume expansion to retain integrity of the electrode during cycling. As a result, the obtained Si composite anode (CF-LM-CA@Si) demonstrates a discharge capacity of 3.14 mAh cm^-2 after 100 cycles at 0.4 A g^-1, corresponding to 76.1% capacity retention rate based on the initial discharge capacity and delivers comparable performance in full cells. The present study provides an applicable prototype of high-energy density electrodes for LIBs.

An ultrastable sodium-ion battery anode enabled by carbon-coated porous NaTi2(PO4)3 olive-like nanospheres

NaTi₂(PO₄)₃ (NTP) is a promising anode material for sodium-ion batteries (SIBs). It has drawn wide attention because of its stable three-dimensional NASICON-type structure, proper redox potential, and large accommodation space for Na⁺. However, the inherent low electronic conductivity of the phosphate framework reduces its charge transfer kinetics, thus limiting its exploitation. Therefore, this paper proposes a material with carbon-coated porous NTP olive-like nanospheres (p-NTP@C) to tackle the issues above. Based on experimental data and theoretical calculations, the porous structure of the material is found to be able to provide more active sites and shorten the Na⁺ diffusion distance. In addition, the carbon coating can effectively improve the electron and Na⁺ diffusion kinetics. As the anode material for SIBs, the p-NTP@C olive-like nanospheres exhibit a high reversible capacity (127.3 mAh g^-1 at 0.1 C) and ultrastable cycling performance (84.8% capacity retention after 10,000 cycles at 5 C). Furthermore, the sodium-ion full cells, composed of p-NTP@C anode and Na₃V₂(PO₄)₂F₃@carbon cathode, also deliver excellent performance (75.7% capacity retention after 1000 cycles at 1 C). In brief, this nanostructure design provides a viable approach for the future development of long-life and highly stable NASICON-type anode materials.

N-Type Polyoxadiazole Conductive Polymer Binders Derived High-Performance Silicon Anodes Enabled by Crosslinking Metal Cations

The dilemma of employing high-capacity battery materials and maintaining the electrodes' electrical and mechanical integrity requires a unique binder system design. Polyoxadiazole (POD) is an n-type conductive polymer with excellent electronic and ionic conductive properties, which has acted as a silicon binder to achieve high specific capacity and rate performance. However, due to its linear structure, it cannot effectively alleviate the enormous volume change of silicon during the process of lithiation/delithiation, resulting in poor cycle stability. This paper systematically studied metal ion (i.e., Li+, Na+, Mg2+, Ca2+, and Sr2+)-crosslinked PODs as silicon anode binders. The results show that the ionic radius and valence state remarkably influence the polymer's mechanical properties and the electrolyte's infiltration. Electrochemical methods have thoroughly explored the effects of different ion crosslinks on the ionic and electronic conductivity of POD in the intrinsic and n-doped states. Attributed to the excellent mechanical strength and good elasticity, Ca-POD can better maintain the overall integrity of the electrode structure and conductive network, significantly improving the cycling stability of the silicon anode. The cell with such binders still retains a capacity of 1770.1 mA h g-1 after 100 cycles at 0.2 C, which is ∼285% that of the cell with the PAALi binder (620.6 mA h g-1). This novel strategy using metal-ion crosslinking polymer binders and the unique experimental design provides a new pathway of high-performance binders for next-generation rechargeable batteries.

In Situ Prepared Three-Dimensional Covalent and Hydrogen Bond Synergistic Binder to Boost the Performance of SiOx Anodes for Lithium-Ion Batteries

Polymer binders play an important role in enhancing the electrochemical performance of silicon-based anodes to alleviate the volume expansion for lithium-ion batteries. It is difficult for common one-dimensional (1D) linear binders to limit the volume expansion of a silicon-based electrode when combined with silicon-based particles with scant binding points. Therefore, it is necessary to design a three-dimensional (3D) network structure, which has multiple binding points with the silicon particles to dissipate the mechanical stress in the continuous charge and discharge circulation. Here, a covalent and hydrogen bond synergist 3D network green binder (poly(acrylic acid) (PAA)-dextrin 9 (Dex₉)) was prepared by the simple in situ thermal condensation of a one-dimensional liner binder PAA and Dex in the electrode fabrication process. The optimized SiO_x@PAA-Dex₉ electrode exhibits an initial Coulombic efficiency (ICE) of 82.4% at a current density of 0.2 A g^-1. At a high current density of 1 A g^-1, it retains a capacity of 607 mAh g^-1 after 300 cycles, which is approximately twice as high as that of the SiO_x@PAA electrode. Furthermore, the results of in situ electrochemical dilatometry (ECD) and characterization of electrode structures demonstrate that the PAA-Dex₉ binder can effectively buffer the huge volume change and maintain the integrity of the SiO_x electrodes. The research overcomes the low electrochemical stability difficulty of the 3D binder and sheds light on developing the simple fabrication procedure of an electrode.

Intrinsically Self-Healing Polymers: From Mechanistic Insight to Current Challenges

Self-healing materials open new prospects for more sustainable technologies with improved material performance and devices' longevity. We present an overview of the recent developments in the field of intrinsically self-healing polymers, the broad class of materials based mostly on polymers with dynamic covalent and noncovalent bonds. We describe the current models of self-healing mechanisms and discuss several examples of systems with different types of dynamic bonds, from various hydrogen bonds to dynamic covalent bonds. The recent advances indicate that the most intriguing results are obtained on the systems that have combined different types of dynamic bonds. These materials demonstrate high toughness along with a relatively fast self-healing rate. There is a clear trade-off relationship between the rate of self-healing and mechanical modulus of the materials, and we propose design principles of polymers toward surpassing this trade-off. We also discuss various applications of intrinsically self-healing polymers in different technologies and summarize the current challenges in the field. This review intends to provide guidance for the design of intrinsic self-healing polymers with required properties.