Ion Transport Channels Research Articles

Attapulgite-Reinforced Cellulose Hydrogels with High Conductivity and Antifreezing Property for Flexible Sensors.

Ionic conductive cellulose hydrogels are some of the most promising candidates for flexible sensors. However, it is difficult to simultaneously prepare cellulose hydrogels with high mechanical strength, good ionic conductivity, and antifreeze performance. In this work, a natural clay (attapulgite)-reinforced cellulose hydrogel was fabricated. Through a one-pot method, cellulose and attapulgite were dispersed in a concentrated ZnCl2 solution. The obtained hydrogel exhibited a dual network of hydrogen bonds and Zn2+-induced ionic interactions. Attapulgite serves as an inorganic filler that can regulate the hydrogen-bonding density among cellulose molecules and provides abundant channels for fast ion transport. By optimizing the attapulgite loading, a mechanically strong (compressive strength up to 1.10 MPa), tough (fracture energy up to 0.36 MJ m-3), highly ionic conductive (4.15 S m-1), and freezing-tolerant hydrogel was prepared. These hydrogels can be used for sensitive and stable human motion sensing, demonstrating their great potential for healthcare applications.

Suppressing the P2–OP4 phase transition of single-crystal P2-type Ni/Zn/Mn-based layered oxide for advanced sodium-ion batteries

P2-type layered Na0.66Ni0.26Zn0.07Mn0.67O2 (NNZM) is expected to be a competitive alternative to lithium layered oxide due to its high-energy-density, low production cost, and high-speed Na+ ion transport channels. However, it is still necessary to further improve its air stability and cycle life to meet the needs of practical applications. Single crystals with micron-scale have smaller specific surface area and greater packing density, which can improve air stability and cycle life compared to the traditional polycrystalline. Herein, single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 (SC-NNZM) is prepared by using Na2MoO4 as the molten salt. Driven by molten salt Na2MoO4, regular hexagonal prism morphology SC-NNZM with a median diameter (D50) of 7.86 μm and the (001) plane-dominated structure is obtained, larger than that (5.05 μm) of single-crystal C-NNZM without Na2MoO4, implying that specific surface area of SC-NNZM is smaller than that of C-NNZM, thereby reducing the contact area of SC-NNZM with the electrolyte, which is good for suppressing both harmful interface side-reactions and phase transitions at high voltages. Therefore, SC-NNZM exhibits 95.44 % capacity retention at 100 mA g−1 after 100 cycles, higher than C-NNZM (86.09 %). Moreover, rate capability of SC-NNZM is also higher than that of C-NNZM. This study provides a new strategy for inducing crystal plane growth that is conducive to the structure stability of single-crystal layered oxide at high voltages.

In Situ Construction of Crumpled Ti3C2Tx Nanosheets Confined S-Doping Red Phosphorus by Ti-O-P Bonds for LIBs Anode with Enhanced Electrochemical Performance.

Red phosphorus (RP) with a high theoretical specific capacity (2596 mA h g-1) and a moderate lithiation potential (∼0.7 V vs Li+/Li) holds promise as an anode material for lithium-ion batteries (LIBs), which still confronts discernible challenges, including low electrical conductivity, substantial volumetric expansion of 300%, and the shuttle effect induced by soluble lithium polyphosphide (LixPPs). Here, S-NRP@Ti3C2Tx composites were in situ prepared through a phosphorus-amine-based method, wherein S-doped red phosphorus nanoparticles (S-NRP) grew and anchored on the crumpled Ti3C2Tx nanosheets via Ti-O-P bonds, constructing a three-dimensional porous structure which provides fast channels for ion and electron transport and effectively buffers the volume expansion of RP. Interestingly, based on the results of adsorption experiments of polyphosphate and DFT calculation, Ti3C2Tx with abundant oxygen functional groups delivers a strong chemical adsorption effect on LixPPs, thus suppressing the shuttle effect and reducing irreversible capacity loss. Furthermore, S-doping improved the conductivity of red phosphorus nanoparticles, facilitating Li-P redox kinetics. Hence, the S-NRP@Ti3C2Tx anode demonstrates outstanding rate performance (1824 and 1090 mA h g-1 at 0.2 and 4.0 A g-1, respectively) and superior cycling performance (1401 mAh g-1 after 500 cycles at 2.0 A g-1).

Hierarchical graphene oxide/nano-pyramidal stainless-steel on nickel foam substrate: A flexible electrochemical sensor for arsenic compound detection

The organoarsenic compound roxarsone (ROX) is added to chicken feed to enhance nutritional value. Although organic arsenic is generally less harmful than inorganic arsenic, concerns have arisen about its potential to transform into inorganic forms when excreted in animal waste, raising environmental and human health concerns. The potential dangers of long-term ROX exposure require reliable methods for the detection of the target analyte. In the current study, fabricated nanoscale graphene oxide (GO)/stainless steel (SS) pyramidal structures on nickel foam (NF) is used as an electrode in the electrochemical detection of ROX. The proposed sensor was shown to outperform existing devices in terms of electrochemical activity, resulting in a wider linear range of detection for ROX (0.05–83.15 µM) and lower detection limit (LOD) (0.006 µM). Further, real sample analysis on water and meat samples confirmed the feasibility of the proposed GO/SS/NF sensor for the real-time detection of ROX in real-world applications. This research provides evidence to support the development of heterojunctions to improve ion transport channels and surface-active sites to promote ion mobility to enhance electrochemical responses.

Construction of MXene interlayer conductive ion transport channel by polypyrrole-coated cellulose nanofibers for ultralow voltage high-performance ionic soft actuators

Ionic soft actuators are extensively utilized in soft robotics and intelligent flexible devices due to their low-voltage actuation capability. MXene(Ti3C2Tx) has potential value as an electrode material for ionic soft actuators owing to its high conductivity and large specific surface area. However, the actuation performance of its ionic soft actuator is limited by poor extensibility and low capacitance caused by the stacking effect. Here, a high-performance ionic soft actuator with MXene\\polypyrrole-coated cellulose nanofibers (CNF@PPy) is reported. While gaining high flexibility of the electrode due to the great mechanical property of CNF, the fast conductive transport channel is constructed by doping CNF@PPy between MXene layers, which not only effectively reduces the loss of conductive properties and drastically improves the ion migration rate, but also prevents MXene from stacking and has additional chemical active sites, significantly increasing its ion storage capacity. Consequently, the actuator exhibits excellent actuation performance at the 0.5 V ultralow voltage: 0.79 % bending strain, 6 s rapid response, and 91.03 % high durability after 5 hours. Additionally, the potential for the actuating core of advanced flexible electronic devices is demonstrated by the application of flexible forceps and the flexible electronic eye.

Increased interlayer spacing N-doping Ti3C2Tx MXene-based mezzanine heterostructure for enhanced performance lithium/sodium storage

Structure of the electrode materials play a critical role in electrochemical performance for both lithium-ion batteries and sodium ion batteries. Herein, MXene modified by element doping and compositing metal–organic frameworks (MOF)-based Fe2O3@Carbon nanofibers (CNFs) with a mezzanine heterostructure, is constructed to achieve low interfacial impedance, high specific capacity stability in lithium/sodium storage processes. The prepared mezzanine heterostructure Fe2O3@C@N-Ti3C2Tx composite is highly conductive and mesoporous. During the nitrogen-doping thermal treatment process, the interlayer spacing of Ti3C2Tx MXene was increased, providing wider ion transport channels. Additionally, inert carbon atoms were transformed into electrochemically active nitrogen atoms, leading to the construction of more active centers and surface defects. The spatial confinement of N-Ti3C2Tx MXene during the electrochemical process, effectively mitigating volume expansion and maintaining structural stability upon applied as electrode materials. Benefitting from the unique 3D conductive network, the mezzanine heterostructure Fe2O3@C@N-Ti3C2Tx composite nanofibers exhibits excellent Li/Na storage performance. In LIBs, it delivers a capacity of 226 mAh/g at 10 A/g and retains 314 mAh/g after 2800 ultra-long cycles at 5 A/g. For SIBs, it exhibits a capacity of 135 mAh/g at 5 A/g and maintains 209 mAh/g after 3000 cycles at 2 A/g.

Revealing the regulation mechanism of Na3V2(PO4)2O2F crystal growth in sodium alginate solution for high-performance sodium ion batteries

Na3V2(PO4)2O2F (NVPFO) attracts tremendous attention as a cathode material for sodium-ion batteries (SIBs) because of its higher capacity and structural stability. However, its inherent poor conductivity affects rate performance and long cycle performance. Herein, a special lamellar NVPFO are successfully synthesized by sodium alginate (SA) assisted hydrothermal method. SA dissolves in water to form hydrogel, due to the specific cross-linking of SA and V4+, which restricts the crystal growth of nanoparticles. Meanwhile, a conductive carbon layer for sodium ion transport channels is constructed after carbonization. Based on multidimensional experiments and density functional theory (DFT) calculations, a mechanism for formation of special lamellar NVPFO in SA solution is proposed for the first time. The results show that special lamellar morphology shortens Na+ migration path and conductive coating facilitates electronic transmission. The optimized NVPFO@C-2 has better electrochemical performance with outstanding high rate capacity (106.8 mAh g–1 at 15 C) and long-term cyclability (99.8 mAh g−1 capacity retention of 87.1 % even after 1000 cycles at 5 C).

Se-doped cobalt-nickel sulfide hollow nanospheres with heterostructure and engineered defects as high-performance electrode for supercapacitors

Porous structures with heterogeneous interfaces and defects are an important way to enhance electrochemically active sites and facilitate electron transfer, while also improving the permeability of the electrolyte and the rate of ion transport. In this study, Se-doped cobalt-nickel sulfide (Se-CoNi2S4) hollow nanospheres with heterostructure and defects were prepared from CoNi metal-organic framework (MOF) as substrate by sequential sulfidation and selenization treatments. Notably, the hollow structure not only offers additional ion transport channels to promote rapid transfer of ions in the electrolyte but also provides an increased number of electrochemically active sites. The morphology and electrochemical performance of Se-CoNi2S4 nanospheres with different levels of Se doping were compared. From the results, Se doping not only enhances the conductivity of CoNi2S4 but also increases its charge storage capacity. As an electrode material, the synthesized Se-CoNi2S4 composite that was synthesized demonstrated a notable specific capacitance of 1260 F g−1 at 1 A g−1. Additionally, when Se-CoNi2S4 was utilized as the anode and activated carbon served as the cathode in an asymmetric supercapacitor, it achieved an energy density of 44.6 Wh kg−1 at a power density of 827 W kg−1. After undergoing 10,000 cycles, this device demonstrated exceptional cycling stability, retaining 80.2 % of its initial capacitance. Therefore, the synthesized electrode material Se-CoNi2S4 has significant potential for energy storage applications.

Asymmetric lithium supercapacitors with solid-state hybrid electrolytes containing zeolite particle and water-soluble polymer

Here we demonstrate that high-performance solid-state hybrid electrolytes are prepared via environment-friendly water-based processes of zeolite Y (Zy) particle, branched-poly(ethylene imine) (bPEI), and lithium hydroxide (LiOH). The hybrid Zy:bPEI:LiOH electrolytes (ZyPL) were successfully applied to fabricate asymmetric-type lithium supercapacitors consisting of graphite-based active electrodes and indium-tin-oxide (ITO) counter electrodes. Results showed that the ion conductivity of electrolytes was greatly dependent on the Zy content and reached the highest value (ca. 0.28 mS/cm) at Zy = 30 wt% due to the formation of interfacial ion transport channels between Zy particles and bPEI chains. The galvanostatic charging/discharging (GCD) test revealed that the ZyPL supercapacitors could deliver the highest potential of 2.28 V at Zy = 30 wt% compared to 1.86 V at Zy = 0 wt%. In particular, the ZyPL supercapacitors, after charging at 0.1 mA/g, exhibited a long-lasting high-potential level of > 1.0 V at Zy = 30 wt% compared to 0.5 V at Zy = 0 wt%. The long-term GCD cycle test disclosed that the ZyPL supercapacitors could work stably with a capacitance retention of 91.7 % even after 3000 cycles. The series connection of six ZyPL supercapacitors delivered ca. 10.94 V with consistent charging/discharging characteristics.

The collaborative effect of Ni3S2-NiO heterojunction and porous carbon network modified lithium-sulfur battery separator for effectively inhibiting polysulfides shuttle

As an important part of lithium-sulfur battery (LSB), separator not only provides ion transport channel but also plays a key role in ensuring battery safety. However, the aperture of the commercial separator polypropylene (PP) is relatively large, which cannot effectively inhibit the migration of polysulfides generated during the charging and discharging process between the positive and negative electrodes, resulting in a decrease in the cycle stability of LSB. In this work, a modified LSB separator Ni3S2-NiO@AC-4@PP is designed, which is anchored by Ni3S2-NiO heterojunction on volcanic rock-like three-dimensional porous carbon network (AC) as the functional interlayer. The AC possesses a large specific surface area and excellent electrical conductivity, creating sufficient space for the physical and chemical adsorption of insoluble polysulfides. The Ni3S2-NiO heterojunction is embedded and attached to the AC, which helps to hinder the diffusion of polysulfides and accelerate the redox reaction. It is also confirmed by density functional theory (DFT) calculation that Ni3S2-NiO heterojunction inhibited the shuttle of polysulfides through the adsorption capacity of NiO and the catalytic activity of Ni3S2. Thus, the Ni3S2-NiO@AC-4@PP battery exhibits an elevated initial specific capacity of 1027.8 mAh g−1 at 0.2C, maintaining long-term stability after 200 cycles with the capacity retention rate of 81.4 %. At the higher current density (2C), Ni3S2-NiO@AC@PP battery demonstrates durable cycle with the capacity retention rate of 91.3 %. This study proposes a new feasible strategy to obtain high-performance, low-cost modified separators by designing functional interlayers with excellent adsorption and catalytic properties.

Pd2+-coordinated polybenzimidazole membranes with fast and selective ion transport for alkaline aqueous organic redox flow battery

The advancement of aqueous organic redox-flow batteries (AORFBs) is impeded by the lack of efficient, low-resistance, and highly selective ion-conducting membranes (ICMs). Although polybenzimidazole (PBI) is one of the most promising low-cost non-fluorinated ion-conducting membranes, it remains challenging to design stable PBI membranes with fast and selective ion transport channels. Here, we engineer the chemical structure of PBI and regulate the ion transport channels to prepare highly conductive and selective Pd2+-coordinated membranes with grafting and crosslinking structures. In this design, the positively charged quaternary ammonium groups on the side chain improve the conductivity of OH−, while the continuous cross-linked network formed by ionic bonds between quaternary ammonium groups and deprotonated imidazole groups significantly enhances the membrane's mechanical properties. Furthermore, the coordination of Pd2+ with PBI and plasticization of PBI chain by trifluoroacetate anions expand the molecular free volume while inducing local contraction. Consequently, the QPBI-xPBI-Pd membrane enables fast charge carrier transport and suppresses the diffusion of active substances. The AORFBs assembled with the QPBI-10PBI-Pd membranes exhibit high coulombic efficiency (99.6 %) and energy efficiency (77.67 %) at 100 mA cm−2, maintaining excellent stability for 500 cycles. This study provides an innovative strategy to design high-performance PBI membranes for RFBs, thereby advancing the viability of RFBs in the realm of large-scale energy storage technologies.

Dual Li ion transport channels in a dynamical supramolecular solid electrolyte toward safety and high-performance Li metal batteries

The polymer based quasi-solid electrolyte (QSE), which combines the high ionic conductivity of the liquid electrolytes with the excellent mechanical flexibility of the polymer matrix, is highly desired and most promising for Li metal batteries (LMBs). However, the Li+ transfer pathways in QSE is not clear enough, and the practical applications in LMBs are also hindered by safety hazards arising from risks of mechanical damage, flammability and high voltage instability. Here, a dynamical supramolecular QSE with abundant hydrogen bonds to fabricate stable and safety LMBs, is reported. In this designed electrolyte, both thermal stability and superior interface stability with anode/cathode electrodes were achieved. Notably, the dual Li+ transport channels in QSE were investigated using in-situ FTIR technology and DFT calculations, providing insights into both the “wet” liquid phase and “dry” polymer chain channels. Benefiting from this design, the Li||NCM622 full batteries based on this QSE exhibit excellent long-term cycling stability.

Highly Tough Slide‐Crosslinked Gel Polymer Electrolyte for Stable Lithium Metal Batteries

AbstractGel polymer electrolytes (GPEs) hold great promise for the practical application of lithium metal batteries. However, conventional GPEs hardly resists lithium dendrites growth and maintains long‐term cycling stability of the battery due to its poor mechanical performance. Inspired by the slide‐ring structure of polyrotaxanes (PRs), herein we developed a dynamic slide‐crosslinked gel polymer electrolyte (SCGPE) with extraordinary stretchability of 970.93 % and mechanical strength of 1.15 MPa, which is helpful to buffer the volume change of electrodes and maintain mechanical integrity of the battery structure during cycling. Notably, the PRs structures can provide fast ion transport channels to obtain high ionic conductivity of 1.73×10−3 S cm−1 at 30 °C. Additionally, the strong polar groups in SCGPE restrict the free movement of anions to achieve high lithium‐ion transference number of 0.71, which is favorable to enhance Li+ transport dynamics and induce uniform Li+ deposition. Benefiting from these features, the constructed Li|SCGPE‐3|LFP cells exhibit ultra‐long and stable cycle life over 1000 cycles and high‐capacity retention (89.6 % after 1000 cycles). Even at a high rate of 16 C, the cells deliver a high capacity of 79.2 mAh g−1. The slide‐crosslinking strategy in this work provides a new perspective on the design of advanced GPEs for LMBs.

Single-ion-conducted covalent organic framework serving as Li-ion pump in polyethylene oxide-based electrolyte for robust solid-state Li–S batteries

Poly(ethylene oxide) (PEO)-based electrolytes are widely used for building solid-state lithium–sulfur (Li–S) batteries but suffer from poor lithium-ion (Li+) transportation kinetics. Here, a lithium-sulfonated covalent organic framework (TpPa-SO3Li) was synthesized and functionalized as a Li+ pump in a PEO-based solid-state electrolyte to fabricate robust Li–S batteries. The designed TpPa-SO3, Li with its porous skeleton and abundant lithium sulfonate groups not only provided iontransport channels but also enhanced the fast migration of Li+. The PEO composite electrolyte containing 5 %-TpPa-SO3Li exhibited a notable ionic conductivity of 6.28 × 10−4 S cm−1 and an impressive Li+ transference number of 0.78 at 60 °C. As a result, Li–Li symmetric batteries with the optimized PEO/TpPa-SO3Li composite electrolyte stably cycled for 300 h, with a minimal overpotential of only 100 mV at 0.5 mA cm−2. Moreover, the customized solid-state Li–S batteries based on PEO/TpPa-SO3Li were stable for 600 cycles at 60 oC with a high Coulombic efficiency of approximately 98 %. This study provides a promising strategy for introducing covalent-organic-framework (COF)-based Li+ pumps to build robust solid-state Li–S batteries.

Synergistic enhancement of ion/electron transport by ultrafine nanoparticles and graphene in Li2FeTiO4/C/G nanofibers for symmetric Li-ion batteries

Low-cost Fe-based disordered rock salt (DRX) Li2FeTiO4 is capable of providing high capacity (295 mA h g−1) by redox activity of cations (Fe2+/Fe4+ and Ti3+/Ti4+) and anionic oxygen. However, DRX structures lack transport channels for ions and electrons, resulting in sluggish kinetics, poor electrochemical activity, and cyclability. Herein, graphene conductive carbon network permeated Li2FeTiO4 (LFT/C/G) nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method. Ultrafine Li2FeTiO4 nanoparticles (2 nm) and one-dimensional (1D) structure provide abundant active sites and unobstructed diffusion channels, accelerating ion diffusion. In addition, introducing graphene reduces the band gap and Li+ diffusion barrier and improves the dynamic properties of Li2FeTiO4, thus achieving a relatively mild interfacial reaction and reversible redox reaction. As expected, the LFT/C/1.0G cathode delivers a remarkable discharge capacity (238.5 mA h g−1), high energy density (508.8 Wh kg−1), and excellent rate capability (51.2 mA h g−1 at 1.0 A g−1). Besides, the LFT/C/1.0G anode also displays a high capacity (514.5 mA h g−1 at 500 mA g−1) and a remarkable rate capability (243.9 mA h g−1 at 8 A g−1). Moreover, the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g−1 after 100 cycles at 50 mA g−1. This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.

Scalable Ni12P5-Coated Carbon Cloth Cathode for Lithium–Sulfur Batteries

As a better alternative to lithium-ion batteries (LIBs), lithium–sulfur batteries (LSBs) stand out because of their multi-electron redox reactions and high theoretical specific capacity (1675 mA h g−1). However, the long-term stability of LSBs and their commercialization are significantly compromised by the inherently irreversible transition of soluble lithium polysulfides (LiPS) into solid short-chain S species (Li2S2 and Li2S) and the resulting substantial density change in S. To address these issues, we used activated carbon cloth (ACC) coated with Ni12P5 as a porous, conductive, and scalable sulfur host material for LSBs. ACC has the benefit of high electrical conductivity, high surface area, and a three-dimensional (3D) porous architecture, allowing for ion transport channels and void spaces for the volume expansion of S upon lithiation. Ni12P5 accelerates the breakdown of Li2S to increase the efficiency of active materials and trap soluble polysulfides. The highly effective Ni12P5 electrocatalyst supported on ACC drastically reduced the severity of the LiPS shuttle, affected the abundance of adsorption–diffusion–conversion interfaces, and demonstrated outstanding performance. Our cells achieved near theoretical capacity (>1611 mA h g−1) during initial cycling and superior capacity retention (87%) for >250 cycles following stabilization with a 0.05% decay rate per cycle at 0.2 C.

Integration of highly sensitive large-area graphene-based biosensors in an automated sensing platform

Graphene-based biosensors, featuring exceptional electronic, mechanical, and surface properties, have emerged as frontrunners in advanced sensing technologies. However, to achieve widespread industrial adoption, advancements in the fabrication and integration of large-area graphene devices are essential. Critical parameters such as enhanced sensitivity, scalable production methods, economic viability, integration capabilities, and consistent uniformity must be meticulously addressed. In this work, we demonstrate that our ultra-clean, chemical wet transfer protocol of large-area graphene enables a scalable, smooth integration of graphene into an established assay platform for transporter protein drug discovery. Furthermore, we demonstrate sensitive detection of electrolytic buffers, varying pH, bovine serum albumin (BSA) and single-stranded DNA (ssDNA) adsorption, using our large-area graphene solution-gated field-effect transistor (SGFET) sensors, thereby proving their robust and reliable performance. The sensors’ biocompatibility and ion sensitivity, down to the picomolar range, substantiate their suitability for the investigation of electroactive transport in ion channels and membrane transporters.

Differential expression of ion channel coding genes in the endometrium of women experiencing recurrent implantation failures

Our study probed the differences in ion channel gene expression in the endometrium of women with Recurrent Implantation Failure (RIF) compared to fertile women. We analyzed the relative expression of genes coding for T-type Ca2+, ENaC, CFTR, and KCNQ1 channels in endometrial samples from 20 RIF-affected and 10 control women, aged 22–35, via microarray analysis and quantitative real-time PCR. Additionally, we examined DNA methylation in the regulatory region of KCNQ1 using ChIP real-time PCR. The bioinformatics component of our research included Gene Ontology analysis, protein–protein interaction networks, and signaling pathway mapping to identify key biological processes and pathways implicated in RIF. This led to the discovery of significant alterations in the expression of ion channel genes in RIF women’s endometrium, most notably an overexpression of CFTR and reduced expression of SCNN1A, SCNN1B, SCNN1G, CACNA1H, and KCNQ1. A higher DNA methylation level of KCNQ1’s regulatory region was also observed in RIF patients. Gene-set enrichment analysis highlighted a significant presence of genes involved with ion transport and membrane potential regulation, particularly in sodium and calcium channel complexes, which are vital for cation movement across cell membranes. Genes were also enriched in broader ion channel and transmembrane transporter complexes, underscoring their potential extensive role in cellular ion homeostasis and signaling. These findings suggest a potential involvement of ion channels in the pathology of implantation failure, offering new insights into the mechanisms behind RIF and possible therapeutic targets.

High performance CaCO3-based composites using sodium tripolyphosphate as phase controlling additive: Bamboo fiber driven high strength development

Due to the limited carbonation degree caused by the surface densification of carbonated products, the development of high-strength carbonated composites remains challenging. In this work, bamboo fiber (BFs) is utilized as a reaction reinforcing agent along with sodium tripolyphosphate (STPP) as a CaCO3 phase controlling additive to prepare high-strength bamboo fiber reinforced carbonated wollastonite composites (BFRCWs). The phase composition and microstructure are systematically investigated by multiscale physicochemical analysis, followed by the determination of macro properties and volume deformation. Results indicate that BF and STPP have a synergistic effect on the microstructural formation and macro performance of BFRCWs. STPP-treated BF (ST-BF) can serve as an internal curing agent and the porous structure of BF provides more channels for ion and CO2 transport, whereas CaCO3 phase composition and cementitious behavior is modified by STPP. The addition of ST-BF, particularly for long fibers, accelerates the carbonation reaction, resulting in an increased ratio of poorly crystalline CaCO3 and a refined pore structure. With increasing ST-BF dosage (0–3 vol%), the cementitious reaction is enhanced, but excessive fibers (3 vol%) incorporation introduces additional porosity, consequently reducing compressive strength. The desired pore structure with the optimal 2 vol% ST-BF (3–6 mm) shows the highest strength of 103.5 MPa at 28 days.

Constructing hybrid nitrogen/oxygen-rich surface and hierarchically porous in lignite-based activated carbons as supercapacitor electrode by in-situ soda ash activate strategy

Coal-based activated carbon materials have the limitations of low specific surface area and limited ion mobilization rate, restricting their practical applications. In this study, porous coal-based activated carbon electrodes were prepared via chemical activation using lignite as a precursor for electrochemical energy storage. Using response surface methodology (RSM), the optimal conditions for preparing porous lignite-based activated carbon were identified: an activation temperature of 856 °C, an activation time of 2.6 hours, and a Na2CO3-coal mass ratio of 4.1:1. The pure alkali carbonization process enriched the activated carbon's three-dimensional pore structure, creating numerous ion-transport channels. The best sample (CAC-3) achieved a surface area of 1847.3 m2 g−1. Process optimization enhanced its electrochemical performance, resulting in a specific capacitance of 219.7 F g−1 at 1 A g−1. It maintained good cycling performance after 5000 cycles in a 6 M KOH aqueous solution at a current density of 10 A g−1. In a two-electrode system, the specific capacitance was 175.3 F g−1 at a current density of 1 A g−1. This study offers new insights for advanced energy storage technologies.