Efficient Ion Transport Research Articles

Ultramicrotomy‐Assisted Fabrication of Nanochannels for Efficient Ion Transport and Energy Generation

AbstractNano‐ and angstrom‐scale channels fabricated from 2D‐layered materials provide a unique platform for studying fluidic behavior at atomic‐scale confinement, with applications in desalination, osmotic power generation, and fuel cells. While various fabrication methods exist, achieving precision, scalability, and minimal fabrication time is challenging. Ultramicrotomy‐based nanofabrication is shown here as an efficient approach to create nanofluidic membranes containing nanochannels with atomically flat walls. This approach is compatible with both bottom–up nanolaminates and top–down nanochannels, produces multiple devices from the same 2D assembly and allows swift variation of channel length. Integration of these membranes into macroscopic silicon fluidic‐chips is achieved maintaining the structural and functional properties. The robustness of the sliced membranes is demonstrated through restacked vermiculate laminates that sustain applied pressures and generate ionic streaming currents. Sliced pristine vermiculite channels exhibit charge‐selective ion transport, leading to osmotic power density (Posm/A) ranging from 9.2 to 300.4 Wm−2 under various KCl concentration gradients. Maximum conversion efficiency of 23.3% is obtained at a 100‐fold gradient, yielding Posm/A of 234.6 Wm−2. Short channel lengths sliced by ultramicrotomy contribute to high Posm/A, promising applications of miniature energy devices for pressure‐driven electricity generation and osmotic power generation.

Enhanced performance in lithium metal batteries: A dual-layer solid electrolyte interphase strategy via perfluoropolyether derivative additive

The utilization of metallic lithium at the negative electrode is regarded as the most promising approach to enhance the energy density of current lithium battery systems. However, uncontrolled lithium dendrite growth leading to instability and low coulombic efficiency (CE) hinders the practical application of metallic lithium as the negative electrode. This study unveils the synthesis of a perfluoropolyether (PFPE) derivative electrolyte additive, denoted as PPP, through reversible addition-fragmentation chain transfer (RAFT) polymerization involving 2-butylsulfanyl-thiocarbonylsulfanyl-propionic acid (PABTC), PFPE and polydioxolane acrylate (PDXLA) as precursors. This additive incorporates fluorinated segments to enhance lithium ion transport efficiency, along with organic segments to improve battery stability. It facilitates the formation of a distinctive dual-layered solid electrolyte interphase (SEI) in 1,3-dioxolane (DOL) based lithium metal batteries. The upper organic protective layer mitigates volume deformation and suppresses lithium dendrite growth, while the lower dense LiF layer enhances lithium ion transport rates, thus improving battery performance. The resulting dual-layer SEI structured LFP | DOL-PPP | Li cell exhibits a capacity retention of 94.1 % after 150 cycles. Moreover, the Li | DOL-PPP | Li cell demonstrates stable cycling performance exceeding 1800 h at 0.2 mA cm-2. This work underscores the significant potential of PFPE derivatives as electrolyte additives in the design and optimization of lithium batteries.

A biomimetic ion channel shortens the QT interval of type 2 long QT syndrome through efficient transmembrane transport of potassium ions

Potassium ion transport across myocardial cell membrane is essential for type 2 long QT syndrome (LQT2). However, the dysfunction of potassium ion transport due to genetic mutations limits the therapeutic effect in treating LQT2. Biomimetic ion channels that selectively and efficiently transport potassium ions across the cellular membranes are promising for the treatment of LQT2. To corroborate this, we synthesized a series of foldamer-based ion channels with different side chains, and found a biomimetic ion channel of K+ (BICK) with the highest transport activity among them. The selected BICK can restore potassium ion transport and increase transmembrane potassium ion current, thus shortening phase 3 of action potential (AP) repolarization and QT interval in LQT2. Moreover, BICK does not affect heart rate and cardiac rhythm in treating LQT2 model induced by E4031 in isolated heart as well as in guinea pigs. By restoring ion transmembrane transport tactic, biomimetic ion channels, such as BICK, will show great potential in treating diseases related to ion transport blockade. Statement of significanceType 2 long QT syndrome (LQT2) is a disease caused by K+ transport disorder, which can cause malignant arrhythmia and even death. There is currently no radical cure, so it is critical to explore ways to improve K+ transmembrane transport. In this study, we report that a small-molecule biomimetic ion channel BICK can efficiently simulate natural K+ channel proteins on the cardiomyocyte and cure E4031-induced LQT2 in guinea pig by restoring K+ transport function for the first time. This study found that the potassium transmembrane transport by BICK significantly reduced the QT interval, which provides a conceptually new strategy for the treatment of LQT2 disease.

Self-assembled nano-MnS@N,P dual-doped lignite based carbon as high-performance sodium-ion batteries anode

Manganese sulfide (MnS) is a suitable electrode material for use in sodium-ion batteries (SIBs) due to its high theoretical capacity and low cost. However, its practical application is still hampered by disadvantages such as large volume expansion during charging/discharging and limited cycle life. Therefore, reasonable structural design is of great importance in order to achieve an excellent sodium storage performance of the electrode materials for SIBs. Herein, nano-MnS@N,P dual-doped lignite based porous carbon (MnS@N,P-LPC) composite with a single MnS cube encapsulated in an N,P dual-doped lignite derived porous C is successfully prepared as superior anode material for SIBs. The multilayer pore structure and the combined effect of N and P dual-doping can enhance electrochemical performance by supplying more sodium storage sites. After 200 cycles at 0.1 A g−1, the composite complex produced a maximum capacity of 519 mA h g−1 and demonstrated a capacity of 392.5 mA h g−1 even at 1.6 A g−1. It exhibits outstanding cycling stability and superior rate performance. This excellent electrochemical performance is ascribed to the presence of the multilayer pore N,P dual-doped C skeleton, which effectively addresses the volume expansion of MnS particles during charging/discharging and facilitates efficient transport of ions and electrons through an effective conductive network.

Optimizing Ion Optical Design for Laser Ablation Source in Mass Spectrometry

The study focuses on optimizing a Laser Ablation Source (LAS) for use in mass spectrometry, particularly aiming to enhance transmission of ions and and determination of isotopic compositions in diverse matrices at TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN). Critical variables affecting mass spectrometer resolution, such as ion kinetic energy distribution and ion transport are optimized through LAS. The paper explores the importance of consistent initial conditions, ion transport efficiency, and ion capture for accurate and reproducible measurements. Using SIMION software, we optimized ion optical design to tackle challenges like collimating ions travelling off-axis and mass filtering. A significant part of the study is dedicated to ion optic design to enable low abundance measurement of ions of interest (e.g., 10 ions of interest out of 1014 total ions). Techniques like high voltage switching and beam shaping were explored, and the final design aims for high transport efficiency and a 4 mm effective target scan area with maximum transport efficiency. The integration of LAS with a Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF-MS) is expected to yield an analytical tool with high spatial resolution and transport efficiency for isotope abundance measurement.

Efficient ionic transport over wide temperature range in oxide enabled by interfacial reaction of molten carbonate

The development of solid oxide fuel cell (SOFC) operated at low and intermediate temperatures is limited by the poor performance of inorganic ionic conductors. Oxide-based ion conductors have attracted much attention due to their excellent stability and tunable ion conduction behavior. In this study, we propose a new approach for the construction of regulated ionic transport pathways in a composite oxide ionic conductor made of WO3/ZrO2 (WZ) and (Li0.68K0.32)2CO3. The interfacial reaction between WO3/ZrO2 and (Li0.68K0.32)2CO3 is used to enhance the interaction between the oxide and carbonate interfaces and introduce hydrophilic phases for water retention, thus achieving ultra-high ionic conductivity of the oxide/carbonate composites at low and intermediate temperatures. The optimal ionic conductor, 13WZ-30(Li0.68K0.32)2CO3 (13WZ-30C), has a superior ionic conductivity of 25.8-6.28 mS cm−1 from room temperature to 250 °C. The ion conduction mechanism of the composite is investigated. This study emphasizes the significance of interfacial chemistry regulation between oxides and carbonates for achieving superior ion conduction performance.

Carbazole-Based branched Poly(Aryl Piperidinium) membranes for Ultra-Stable anion exchange membrane fuel cells

In the technological development of anion exchange membrane fuel cells (AEMFCs), it is crucial to prepare anion exchange membranes (AEMs) with high conductivity and excellent dimensional stability. This study successfully developed highly branched poly(aryl piperidinium) AEMs by introducing 4,4′-bis(N-carbazolyl)-1,1′-biphenyl as branched linker unit into the poly(p-terphenyl piperidinium) backbone. With the introduction of the carbazole group, the plane-conjugated structure and non-rotatable properties are fully utilised, which effectively reduces the entanglement between the polymer backbones and increases the free volume of the AEMs, hence facilitates the construction of an efficient ion transport channel. The branched structure effectively reduces the water uptake of the membrane which leads to improved dimensional stability. The optimized QPCBP-TP-7 membrane exhibited high conductivity, reaching up to 151.88 mS cm−1 at 80 °C, along with excellent mechanical strength (TS = 42.51 MPa, EB = 13.32 %, wet state) and dimensional stability (SR of 22.9 % at 80 °C). Surprisingly, this membrane also exhibited favorable antioxidant properties (retaining over 97.28 % weight after 96 h in Fenton's reagent at 80 °C), and alkaline stability (retaining over 86.81 % efficacy after 1500 h in 5 M NaOH solution at 80 °C). In AEMFCs applications, the QPCBP-TP-7 membrane achieved peak power density (PPD) up to 616 mW cm−2 with the current density is 1330 mA cm−2 at 80 °C (H2-O2) and the QPCBP-TP-7 membrane remained stable and hardly degraded when operated at constant current of 0.1 A cm−2 (80 °C) over 100 h.

Synthesis and self-assembly of bottlebrush block copolymer electrolytes for solid-state supercapacitors

All-solid-state supercapacitors have attracted increasing attention in recent decades owing to rapid advancements in safe, flexible, and wearable energy storage devices. This study demonstrates a bottlebrush block copolymer electrolyte consisting of poly(styrene-b-butadiene-b-styrene)-g-poly(ethylene glycol) behenyl ether methacrylate (SBS-g-PEGBEM) (simply SgP) for all-solid-state supercapacitors. Due to the adhesive nature and robust mechanical properties of SgP film, devices can be manufactured without the need for separators or packaging. The nonpolar SBS domains serve as scaffolds within the polymer matrix, while the polar PEGBEM domains offer interactive sites for polar ionic liquids (ILs). The synergy between precisely defined nanostructures and the subsequent well-dissociated ions enhances efficient ion transport through the ionic channels. As a result, the supercapacitor with SgP/IL electrolyte exhibits remarkable electrochemical performance. This includes a wide potential window of 2.4 V, an ionic conductivity of 2.4 mS cm−1, and maximum energy density and power density of 28.1 Wh kg−1 and 3080 W kg−1, respectively. The supercapacitor also demonstrates high cycle stability with 87.7 % capacitance retention after 5,000 cycles. The positive impact of the PEGBEM side chains is investigated via molecular dynamics simulations. Thus, this study presents a novel strategy for solid-state electrolytes, offering potential advancements in next-generation energy storage devices.

Chitosan Composite Membrane with Efficient Hydroxide Ion Transport via Nano-Confined Hydrogen Bonding Network for Alkaline Zinc-Based Flow Batteries.

The development of membranes with rapid and selective ionic transport is imperative for diverse electrochemical energy conversion and storage systems, including fuel cells and flow batteries. However, the practical application of membranes is significantly hindered by their limited conductivity and stability under strong alkaline conditions. Herein, a unique composite membrane decorated with functional Cu2+ cross-linked chitosan (Cts-Cu-M) is reported and their high hydroxide ion conductivity and stability in alkaline flow batteries are demonstrated. The underlying hydroxide ions transport of the membrane through Cu2+ coordinated nano-confined channels with abundant hydrogen bonding network via Grotthuss (proton hopping) mechanism is proposed. Consequently, the Cts-Cu-M membrane achieves high hydroxide ion conductivity with an area resistance of 0.17Ωcm2 and enables an alkaline zinc-based flow battery to operate at 320mAcm-2, along with an energy efficiency of ≈80%. Furthermore, the membrane enables the battery for 200cycles of long-cycle stability at a current density of 200mAcm-2. This study offers an in-depth understanding of ion transport for the design and preparation of high-performance membranes for energy storage devices and beyond.

Anion exchange membrane based on poly(arylene ether sulfone)s functionalized with quinuclidinium-piperidinium dual cations for vanadium redox flow battery applications

Vanadium redox flow batteries (VRFBs) have gained significant interest as a prospective energy storage solution due to their scalability and extended cycle durability. The efficient functioning of VRFBs relies significantly on anion exchange membranes (AEMs), which facilitate the selective transport of ions while preventing crossover. In this study, we present a novel AEM based on poly(arylene ether sulfone)s (PAES) functionalized with dual cations (quinuclidinium-piperidinium) (DC-PAES) bearing a butyl spacer, explicitly designed for VRFB applications. The DC-PAES membrane containing dual cations separated by a butyl spacer results in a balanced combination of hydrophilicity and hydrophobicity, which enables efficient ion transport across the membrane. The DC-PAES membrane showed hydroxide conductivity of 0.085 S/cm at 80 °C, having an ion exchange capacity (IEC) of 1.42 mmol/g. The resulting DC-PAES membrane displayed low permeability (2.1 × 10−7 cm2 min−1) and high selectivity (12.3 × 105 S min cm−3) to vanadium. The performance of the AEMs fabricated for VRFB application showed better Coulombic (97.1 %), energy (90.0 %), and voltage efficiency (92.63 %) at 40 mAcm−2 higher than Nafion 117. The reported AEMs revealed excellent stability due to the steric and ring constraints of quinuclidinium and piperidinium cation, hindering the attack of oxidative species. Furthermore, the DC-PAES membrane demonstrated improved battery cycling performance lasting up to 150 cycles under in-situ conditions, making it a promising separator material for VRFB applications.

Engineering sulfur defective Bi2S3@C with remarkably enhanced electrochemical kinetics of lithium-ion batteries

Introducing the appropriate vacancies to augment the active sites and improve the electrochemical kinetics while maintaining high cyclability is a major challenge for its widespread application in electrochemical energy storage. Here, core–shell structured Bi2S3@C with sulfur vacancies was prepared by hydrothermal method and one-step carbonization/sulfuration process, which significantly improves the intrinsic electrical conductivity and ion transport efficiency of Bi2S3. Additionally, the uniform protective carbon layer around surface of composite maintains structural stability and effectively alleviates volume expansion during alloying/dealloying. As a result, the BSC-500 anode exhibits a brilliant reversible capacity of 636 mAh/g at 0.2 A/g and a long-term stable capacity of 524 mAh/g for 500 cycles at a high current density of 3 A/g in lithium-ion batteries. In addition, the assembled Bi2S3@C//LiCoO2 full cell delivered a capacity of 184 mAh/g at 1 A/g and excellent cyclability (125 mAh/g after 1000 cycles). The proposed strategy of combining sulfur vacancies with a core–shell structure to improve the electrochemical kinetics of Bi2S3 in lithium-ion batteries off the prospect for practical applications of transition metal sulfide anodes.

Reducing hydroxide transport resistance by introducing high fractional free volume into anion exchange membranes

The efficiency of ion transport in solid polyelectrolytes is significantly hindered by tight polymer chain entanglement compared to that in liquids. In this study, a series of hyperbranched poly(aryl piperidinium) anion exchange membranes (AEMs) with 1,3,5-triacetylbenzene as a branching point were synthesized. The hyperbranched structure results in weaker chain entanglement and a larger interchain correlation distance, leading to a higher fractional free volume, thereby greatly reducing ion transport resistance. Consequently, a remarkably higher OH− conductivity of the as-prepared hyperbranched AEM (296 mS cm−1) is achieved compared to that of non-hyperbranched AEMs (180 mS cm−1). Furthermore, the hyperbranched AEMs exhibit excellent fuel cell and water electrolysis performance, with a peak power density of 1.53 W cm−2 in AEMFCs and a current density of 1 A cm−2 at a voltage of 2 V in AEMWEs, respectively.

Flexible films with three-dimensional ion transport channels: Carbon nanotubes@MnO2 as interlayer spacers in porous graphene electrodes for high-performance supercapacitors

Flexible supercapacitors have a high potential for application in wearable electronics and microdevices, but their commercial appeal is limited because of low energy density. To overcoming this challenge, this paper proposes a strategy to fabricate dense films with high specific capacitance. A composite film with rapid ion diffusion channels and a high density of 0.86 g cm–3 was synthesized by combining porous graphene nanosheets (PGNs), carbon nanotubes (CNTs), and MnO2 nanosheets. The incorporation of CNTs@MnO2 between graphene layers effectively mitigated aggregation and enhanced electrolyte ion diffusion within the dense graphene structure. PGNs and CNTs synergistically established a three-dimensional pathway for efficient ion transport while optimizing electron dynamics. In 1 mol L–1 Na2SO4 electrolyte, the material exhibited a gravimetric capacitance of up to 320 F g–1 at 1 A g–1 and a volumetric capacitance reached 275 F cm–3. Furthermore, the assembled asymmetric supercapacitors, PGNs-CNTs@MnO2//PGNs-CNTs, exhibited a gravimetric energy density of up to 26.4 Wh kg–1 and a volumetric energy density of up to 22.7 Wh L–1. These findings offer insights into advancing flexible supercapacitor technology for diverse applications.

Advanced composite material for high-performance supercapacitors: integrating graphene oxide and barium chromate

Graphene oxide-based Barium chromate (BaCr2O4@GO) composites were successfully synthesized through sonication assisted by a hydrothermal process designed for supercapacitor applications. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and morphological analyses were employed to characterize the nanostructured composites. The XRD and FTIR results reveal that the GO nanoparticles are arranged in a honeycomb-like configuration. Moreover, the TEM images reveal the presence of cauliflower-like structures in the morphology of the composites, which is attributed to the effective intercalation of GO during the thermal reduction process. The electrochemical properties of the nanocomposite were compared to those reported in previous studies on metal chromite materials aimed at enhancing supercapacity applications. The analysis of Galvanostatic Charge–Discharge (GCD) data indicates a significant increase in power density values from 292 W kg−1 to 495.5 W kg−1 for the Nanocomposites. The ability to achieve a balance between enhanced power density and efficient ion transport positions the -nanocomposites as a valuable candidate for advancing the performance of supercapacitors.

Pore-structure control of porous carbon electrode materials and energy-storage performance in water-in-salt electrolytes

The pore structure of carbon-based materials and the voltage window of the electrolyte are two key factors affecting the energy density of carbon-based supercapacitors (SCs). In this paper, activated carbon materials of different pore sizes is successfully synthesized by chemical activation method by adjusting the mass ratio of ZnCl2 to sucrose, and successfully applied to construct SCs based on different electrolyte systems. As the specific surface area of the prepared porous carbon materials shows a tendency to increase and then decrease, reaching a maximum in the presence of micropores. Further summarizing the constitutive relationship between pore structure-electrochemical performance in the high-concentration electrolyte system, it is found that the normalized specific capacity is larger at smaller pore sizes, and with the increase of mesoporous proportion, the normalized specific capacity decreases and tends to be stable. In addition, the different strengths of solvation of anions and cations in the electrolyte, with the cations contributing more to the contrast, and the presence of mesopores providing ion transport channels to improve the efficiency of ion transport in porous materials, which provide directions for designing a suitable pore structure for highly concentrated salt electrolytes, as well as another way of optimizing the properties of carbon-based materials for SCs.

Mitigating Joule heating in smart nanochannels: Evaluating the efficacy of AC vs. DC fields

This study delves into the profound implications of different electric field types, namely DC and AC with a sinusoidal waveform, on ion transport within intelligent soft nanochannels, aiming to mitigate Joule heating effects. The investigation considers temperature- and concentration-dependent properties and explores their impact on ionic selectivity, rectification factor, Joule heating, and viscosity dissipation in conical soft nanochannels. Operating in both co-current and counter-current modes, the study accounts for the nanochannel's coating with a dense and strongly negatively charged polyelectrolyte layer, addressing the ionic partitioning effect. Numerically solving the Poisson-Nernst-Planck, Navier-Stokes, and energy equations, the study reveals a significant alignment of Joule heating and viscosity dissipation with ionic current, emphasizing the influence of concentration and temperature ratios. Notably, the bidirectional AC field demonstrates a remarkable 85.51% and 71.72% reduction in Joule heating in co-current and counter-current modes, respectively, compared to DC. These findings highlight the significant impact of the AC field on thermal dynamics within nanochannels. In summary, our study offers essential insights into optimizing nanofluidic systems by effectively balancing ion transport efficiency and thermal effects across various electrical field scenarios. These findings directly address the critical challenge of managing Joule heating in intelligent nanochannels, which is essential for enhancing the performance of lab-on-a-chip devices in sensitive biomedical applications.

Plasma-assisted aerogel interface engineering enables uniform Zn2+ flux and fast desolvation kinetics toward zinc metal batteries

The poor reversibility of Zn anodes induced by dendrite growth, surface passivation, and corrosion, severely hinders the practical applicability of Zn metal batteries. To address these issues, a plasma-assisted aerogel (PAG) interface engineering was proposed as efficient ion transport modulator that can simultaneously regulate uniform Zn2+ flux and desolvation behavior during battery operation. The PAG with ordered mesopores acted as an ion sieve to homogenize Zn deposition and accelerate Zn2+ flux, which is favorable for corrosion resistance and dendrite suppression. Importantly, the plasma-assisted aerogel with abundant hydrophilic groups can facilitate the desolvation kinetics of Zn2+ due to the multiple hydrogen-bonding interaction with the activated water molecules, thus accelerating the Zn2+ migration kinetics. Consequently, the Zn/Zn cell assembled with PAG-modified separator demonstrates stable plating and stripping behavior (over 1400 h at 1 mA cm−2) and high Coulombic efficiency (99.8% at 1 mA cm−2 after 1100 cycles), and the Zn||MnO2 full cell shows excellent long-term cycling stability and maintains a high capacity of 154.9 mA h g−1 after 1000 cycles at 1 A g−1. This study provides a feasible approach for the large-scale fabrication of aerogel functionalized separators to realize ultra-stable Zn metal batteries.

Reactive Carbon Capture Enables CO2 Electrolysis with Liquid Feedstocks.

ConspectusThe electrochemical reduction of carbon dioxide (CO2RR) is a promising strategy for mitigating global CO2 emissions while simultaneously yielding valuable chemicals and fuels, such as CO, HCOO-, and C2H4. This approach becomes especially appealing when integrated with surplus renewable electricity, as the ensuing production of fuels could facilitate the closure of the carbon cycle. Despite these advantages, the realization of industrial-scale electrolyzers fed with CO2 will be challenged by the substantial energy inputs required to isolate, pressurize, and purify CO2 prior to electrolysis.To address these challenges, we devised an electrolyzer capable of directly converting reactive carbon solutions (e.g., a bicarbonate-rich eluent that exits a carbon capture unit) into higher value products. This "reactive carbon electrolyzer" operates by reacting (bi)carbonate with acid generated within the electrolyzer to produce CO2 in situ, thereby facilitating CO2RR at the cathode. This approach eliminates the need for expensive CO2 recovery and compression steps, as the electrolyzer can then then coupled directly to the CO2 capture unit.This Account outlines our endeavors in developing this type of electrolyzer, focusing on the design and implementation of materials for electrocatalytic (bi)carbonate conversion. We highlight the necessity for a permeable cathode that allows the efficient transport of (bi)carbonate ions while maintaining a sufficiently high catalytic surface area. We address the importance of the supporting electrolyte, detailing how (bi)carbonate concentration, counter cations, and ionic impurities impact selectivity for products formed in the electrolyzer. We also catalog state-of-the-art performance metrics for reactive carbon electrolyzers (i.e., Faradaic efficiency, full cell voltage, CO2 utilization efficiency) and outline strategies to bridge the gap between these values and those required for commercial operation Collectively, these findings contribute to the ongoing efforts to realize industrial-scale electrochemical reactors for CO2 conversion, bringing us closer to a sustainable and closed-loop carbon cycle.

Designing a Se-intercalated MOF/MXene-derived nanoarchitecture for advancing the performance and durability of lithium-selenium batteries

Lithium-selenium batteries have emerged as a promising alternative to lithium-sulfur batteries due to their high electrical conductivity and comparable volume capacity. However, challenges such as the shuttle effect of polyselenides and high-volume fluctuations hinder their practical implementation. To address these issues, we propose synthesizing Fe-CNT/TiO2 catalyst through high-temperature sintering of an amalgamated nanoarchitecture of carbon nanotubes decorated metal–organic framework (MOF) and MXene, optimized for efficient selenium hosting, leveraging the distinctive physicochemical properties. The catalytic features inherent in the porous Se@Fe-CNT/TiO2 nanoarchitecture were instrumental in promoting efficient ion and electron transport, and lithium-polyselenide kinetics, while its inherent porosity could play a crucial role in inhibiting electrode stress during cycling. This nanoarchitecture exhibits remarkable battery performance, retaining 99.7% of theoretical capacity after 425 cycles at 0.5 C rate and demonstrating 95.8% capacity retention after 2000 cycles at 1 C rate, with ∼100% Coulombic efficiency. Additionally, the Se@Fe-CNT/TiO2 electrode exhibited an impressive recovery of 297.5 mAh/g (97.9%) capacity after undergoing 450 cycles at a charging rate of 10 C and a discharging rate of 1 C. This synergistic integration of MOF- and MXene-derived materials unveils new possibilities for high-performance and durable LSeBs, thus advancing electrochemical energy storage systems.

Overcoming the Na-ion conductivity bottleneck for the cost-competitive chloride solid electrolytes

Chloride solid electrolytes possess multiple advantages for the construction of safe, energy-dense all-solid-state sodium batteries, but presently the chlorides with sufficiently high cost-competitiveness for commercialization almost all exhibit low Na-ion conductivities of around 10−5 S cm−1 or lower. Here, we report a chloride solid electrolyte, Na2.7ZrCl5.3O0.7, which reaches a Na-ion conductivity of 2.29 × 10−4 S cm−1 at 25 °C without involving overly expensive raw materials such as rare-earth chlorides or Na2S. In addition to the efficient ion transport, Na2.7ZrCl5.3O0.7 also shows an excellent deformability surpassing that of the widely studied Na3PS4, Na3SbS4, and Na2ZrCl6 solid electrolytes. The combination of these advantages allows the all-solid-state cell based on Na2.7ZrCl5.3O0.7 and NaCrO2 to realize stable room-temperature cycling at a much higher specific current than those based on other non-viscoelastic chloride solid electrolytes in literature (120 mA g−1 vs. 12–55 mA g−1); after 100 cycles at such a high rate, the Na2.7ZrCl5.3O0.7-based cell can still deliver a discharge capacity of 80 mAh g−1 at 25 °C.