Alkaline Ion Batteries Research Articles

Mono-/Bimetallic Doped and Heterostructure Engineering for Electrochemical Energy Applications.

Designing efficient materials is crucial to meeting specific requirements in various electrochemical energy applications. Mono-/bimetallic doped and heterostructure engineering have attracted considerable research interest due to their unique functionalities and potential for electrochemical energy conversion and storage. However, addressing material imperfections such as low conductivity and poor active sites requires a strategic approach to design. This review explores the latest advancements in materials modified by mono-/bimetallic doped and heterojunction strategies for electrochemical energy applications. It can be subdivided into three key points: (i) the regulatory mechanisms of metal doping and heterostructure engineering for materials; (ii) the preparation methods of materials with various engineering strategies; and (iii) the synergistic effects of two engineering approaches, further highlighting their applications in supercapacitors, alkaline ion batteries, and electrocatalysis. Finally, the review concludes with perspectives and recommendations for further research to advance these technologies.

2D Se-Rich ZnSe/CoSe2@C Heterostructured Composite as Ultrastable Anodes for Alkaline-Ion Batteries.

2D transitional metal selenide heterostructures are promising electrode materials for potassium-ion batteries (PIBs) owing to the large surface area, high mechanical strength, and short diffusion pathways. However, the cycling performance remains a significant challenge, particularly concerning the electrochemical conversion reaction. Herein, 2D Se-rich ZnSe/CoSe2@C heterostructured composite is fabricated via a convenient hydrothermal approach followed by selenization process, and then applied as high-performance anodes for PIBs. For example, the capacity delivered by the heterostructured composite is mainly contributed to the synergistic effect of conversion and alloy/de-alloy processes aroused by K+, where K+ may highly insert or de-insert into Se-rich ZnSe/CoSe2@C. The obtained electrode delivers an outstanding reversible charge capacity of 214mA h g-1 at 1 A g-1 after 4000 cycles for PIBs, and achieves 262 mAh g-1 when coupled with a PTCDA cathode in the full cell. The electrochemical conversion mechanism of the optimized electrode during cycling is investigated through in situ XRD, Raman, and ex situ HRTEM. In addition, the heterostructured composite as anodes also displays excellent electrochemical performances for sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs). This work opens up a new window for investigating novel electrode materials with excellent capacity and long durability.

Hierarchical Ni3V2O8@N-Doped Carbon Hollow Double-Shell Microspheres for High-Performance Lithium-Ion Storage.

Transition metal oxides (TMOs) are highly dense in energy and considered as promising anode materials for a new generation of alkaline ion batteries. However, their electrode structure is disrupted due to significant volume changes during charging and discharging, resulting in the short cycle life of batteries. In this paper, the hierarchical Ni3V2O8@N-doped carbon (Ni3V2O8@NC) hollow double-shell microspheres were prepared and used as electrode materials for lithium-ion batteries (LIBs). The utilization efficiency and ion transfer rate of Ni3V2O8 were improved by the hollow microsphere structure formed through nanoparticle self-assembly. Furthermore, the uniform N-doped carbon layer not only enhanced the structural stability of Ni3V2O8, but also improved the overall electrical conductivity of the composite. The Ni3V2O8@NC electrode has an initial discharge capacity of up to 1167.3 mAh g-1 at a current density of 0.3 A g-1, a reversible capacity of up to 726.5 mAh g-1 after 200 cycles, and still has a capacity of 567.6 mAh g-1 after 500 cycles at a current density of 1 A g-1, indicating that the material has good cycle stability and high-rate capability. This work presents new findings on the design and fabrication of complex porous double-shell nanostructures.

(Digital Presentation) Hybrid Membranes Engineered from Sustainable Sources Exhibit Improved Ionic Conductivity

Ion-conducting membranes are crucial in electrochemical storage and energy conversion technologies such as fuel cells, alkaline ion batteries, and redox-flow batteries. The purpose of the membrane is to prevent direct contact between the electrodes while allowing selective ions to pass through. The characteristics of the ion-conducting membranes include excellent mechanical and thermal stability, chemical resistance, high ionic conductivity, and selectivity. Polymers and polymer-based precursors make up the majority of the materials that have been used as ion-conducting membranes. However, most polymer-based membranes have issues related to poor chemical resistance, recyclability, and thermal and mechanical stability. In addition, as more sustainable materials are being sought to create a sustainable society, new environmentally friendly and economically viable materials are in high demand. The clay-based material could be an alternative for ion-conducting applications due to its porous structure, high surface area, tunable interlayer spacing, excellent thermal and mechanical stability, and high ion conductivity. Clay minerals are primarily used in water treatment, pharmaceutics, ceramics, paints, and coating industries. Furthermore, clay minerals have been used as a filler material in energy storage and conversion system to improve the thermal stability and ion conductivity in electrodes, electrolytes, and separators.Herein, we report a novel approach to making non-polymeric hybrid clay membranes using environmentally benign materials such as clay and zwitterion (i.e., sulfobetaine). These membranes with improved ionic conductivity will find immense potential in applications in energy storage and conversion systems. Such membranes have been synthesized by intercalating sulfobetaine molecules into the interlayer spacing of the bentonite clay matrix. Sulfobetaine is a zwitterion composed of quaternary ammonium cations and sulfonate anions. Leveraging the unique structure-property features that exist in zwitterions helps to alter the interlayer spacings in the clay matrix, thereby enabling ion diffusion through the silicate layers. Furthermore, it helps in the formation of a self-supporting membrane. The functionalized membrane's crystal structure and chemical composition were investigated using XRD, XPS, and ATR-FTIR. XRD was used to identify the layered structure of the silicates in clay and the increased interlayer spacing (1.15 nm to 1.8 nm) of the hybrid clay membrane. Data from XPS and ATR-FTIR confirmed the successful functionalization of clay with sulfobetaine. Furthermore, the ionic conductivity of the hybrid clay membrane was characterized using a non-aqueous lithium electrolyte solution, and found a conductivity of . This is one of the first reports showcasing how zwitterions can impart conductivity in clay silicate motifs. It suggests an easy and novel approach to transport lithium-ion through silicate layers, thereby making it suitable for use as membranes in batteries and supercapacitors. The current study demonstrates an easy and versatile approach to developing cost-effective and eco-friendly membranes from sustainable materials such as clay, which, when functionalized, has the potential to be a highly efficient ion-conducting material with applications in energy storage, devices, and technologies.

Computational verification of conductive Be2Zn monolayer as a superior anode for alkali and alkaline ion batteries

Availability of high-performance anode materials remains a great challenge for the clean energy storage systems. Here, we predict the planar hexacoordinate Be2Zn monolayer by first-principles calculations as a highly conductive metallic conductor with all-round structural stabilities. More impressively, the material delivers ultrahigh theoretical specific capacities of 1285, 1928, 1285, and 3856 mA h g−1 for Li, Na, K, and Ca atoms, respectively, with low migration barriers of 18, 7, 4, and 119 meV as well as with favorite average open-circuit voltages of 0.346, 0.366, 0.322, and 0.151 V. Its structural reversibility at the maximum loading concentrations is jointly confirmed by ab-initio molecular dynamics simulations at the upper temperature of 400 K for commercial battery operation under normal ambient environments and subsequent energy minimization calculations. Moreover, the monolayer can tolerate heavy tensile strain up to around 20% far surpassing the structural deformations at different charging stages, which convincingly guarantees its superlative cycle stability during the charging and discharging processes. Taken together, these appealing findings show that the metallic Be2Zn monolayer has great potential to be used as a universal Li, Na, K, and Ca ion battery anode.

T-BN nanosheets as High-capacity anode for Li- and Na-Ion Batteries: An ab initio study

An allotrope of graphene named T-graphene has been reported as a promising anode material for the development of the storage capacity of alkaline ion batteries (AIBs). Herein, by first-principles calculations, we have explored the anodic properties of the boron nitride analogue of T-graphene named T-BN. We demonstrate that T-BN hosts stable ion adsorption for both Li- and Na-ion with good structural features. We also found that T-BN has a small bandgap of 1.184 eV, which naturally reduces to zero as ions are adsorbed within the nanosheet. As a result, the theoretical storage capacities are as high as 959.95 mAh/g, and 719.97 mAh/g for Li and Na adsorbed T-BN, respectively, which are much higher than commercial graphite anode. We further show that T-BN has good electrical conductivity, whether it is before and after ion adsorption. Lastly, low open circuit values indicate the superiority of this material as an appealing anode for Li- and Na-ion storage batteries.

Sub-nanometric amorphous V–O clusters without grain boundaries bonded in yolk-shell carbon nanospheres for superior sodium-ion storage

The energy density of sodium-ion batteries (SIBs) reported so far is still low, which weakens their competitiveness in practical applications. Cluster engineering and sub-nanometric design are effective strategies for rapid and efficient storage of alkaline ions. Herein, a durable yolk-shell architecture is developed via a facile self-polymerization and calcination process, in which the sub-nanometric amorphous vanadium-oxide (V–O) clusters are bonded in N-doped carbon nanospheres (A-VOxC/N–C). As a SIB anode, the composite delivers a large reversible capacity (491.6 mAh g−1 at 0.05 A g−1), high-rate capability and ultra-long cyclic stability (246.4 mAh g−1 with 96.6% capacity retention after 30000 cycles at 20.0 A g−1). In addition, the full cell also exhibits great potential for practical applications. The detailed structural characterizations and density functional theory (DFT) calculations suggest that the amorphous clusters without grain boundaries are crucial for the creation of abundant active sites and highly isotropic channels, as well as the reduction of Na-intercalation stress. The yolk-shell N–C has the structural advantages of flexible cavity, strong bonding force and large spatial constraint, which can effectively alleviate volume changes and strengthen structural stability. In view of these, this study can provide guidance for the design of sub-nanometric clusters and their potential applications in alkaline ion batteries.

Adjusting Crystal Orientation to Promote Sodium‐Ion Transport in V5S8@Graphene Anode Materials for High‐Performance Sodium‐Ion Batteries

Sodium-ion batteries (SIBs) have inspired the potential for widespread use in energy storage owing to the advantages of abundant resources and low cost. Benefiting from the layered structure, 2D-layered materials enable fast interlayer transport of sodium ions and thus are considered promising candidates as anodes for SIBs. Herein, a strategy of adjusting crystal orientation is proposed via a solvothermal method to improve sodium-ion transport at the edge of the interlayers in 2D-layered materials. By introducing surfactants and templates, the 2D-layered V5 S8 nanosheets are controlled to align the interlayer diffusion channels vertically to the surface, which promotes the fast transport of Na+ at the edge of the interlayers as revealed by experimental methods and ab initio calculations. Benefiting from the aligned crystal orientation and rGO coating, the vertical-V5 S8 @rGO hybrid delivers a high initial discharge capacity of 350.6 mAh g-1 at a high current density of 15 A g-1 . This work provides a strategy for the structural design of 2D-layered anode materials by adjusting crystal orientation, which demonstrates the promise for applications in fast-charging alkaline-ion batteries.

Insight into thermal regulation of supercapacitors via surface-engineered phase change microcapsules.

Constructing efficient thermal management system to settle the thermal runaway of energy storage devices via employing phase change microcapsules (MEPCMs) is of great significance. However, it is still a challenge that the conventional MEPCMs go against the electrochemical performance and hardly be homogenously fixed in the electrodes. In order to conquer these long-standing critical issues, we designed a novel electrochemically active double-shell phase change microcapsule by introducing polypyrrole on the surface of dense amine resin shell of the conventional inert MEPCM. The active MEPCMs@PPy are uniformly immobilized on the surface of the electrode material using reduced graphene oxide to ensure the stable and efficient operation of the flexible supercapacitor. The assembled all-solid-state supercapacitor containing MEPCMs@PPy (SCs@MEPCMs@PPy) lagged 103s to 55°C than the SCs@00 without the added phase change material. At a high temperature of 55°C and a scan rate of 50mVs-1, SCs@MEPCMs@PPy exhibits an areal specific capacitance of 110.6mAcm-2, which is higher than that of the original SCs@MEPCMs. A capacitance retention of 79.8% and coulombic efficiency of 98.4% can be reached after 3000 cycles. This study opens a new avenue for developing applicable microencapsulated phase change materials in temperature-regulated electrode systems for supercapacitors and alkaline-ion batteries.

Facile synthesis of hairbrush like FeVO4@C/CC anode material with enhanced electrochemical performance for alkaline ion batteries

Facile synthesis of hairbrush like FeVO4@C/CC anode material with enhanced electrochemical performance for alkaline ion batteries

High-performance aqueous potassium ion asymmetric supercapacitors based on tunable 2D transition metal oxides

Rechargeable aqueous potassium ion asymmetric supercapacitors are emerging as a promising alternative to lithium ion batteries due to their low cost and high safety. However, the large size of the potassium ions tends to lead to large deformations and even irreversible shattering of the active material during the insertion/extraction process. In this paper, amorphous/crystalline biphasic KxV2O5 (ac-KxV2O5) is synthesized by electrochemical deposition on three-dimensional nanoporous nickel tube collectors. The amorphous K0.25V2O5∙nH2O acts as a molecular column to maintain the large interlayer spacing of crystalline V2O5 bilayer, providing sufficient space to accommodate as much hydrated potassium ions as possible and their rapid transport, effectively alleviating structural damage to the host material. Benefiting from the large work function difference between V2O5 and MnO2, an aqueous potassium ion asymmetric supercapacitor is assembled using KxV2O5∙nH2O anode and KxMnO2∙nH2O cathode to obtain a volumetric energy of 32.7 mWh cm−3, which is superior not only to commercial energy storage devices but also to previously reported aqueous alkaline ion batteries and supercapacitors.

Embedding anatase TiO2 nanoparticles into holely carbon nanofibers for high-performance sodium/lithium ion batteries

Titanium dioxide (TiO2) has been considered as a promising anode material for alkaline ion batteries (AIBs), yet the low electrical conductivity and sluggish reaction kinetics have restricted its practical applications, while rational structure design can significantly overcome these drawbacks. Herein, we report a one-step fabrication of ultrafine anatase TiO2 nanoparticles within holely carbon nanofibers (denoted as A-TiO2 @HCNFs) via a facile electrospinning method and subsequent annealing treatment. The chemical reaction between TEOS (Si(OC2H5)4) and PVDF ((CH2CF2)n) in the precursor induces the generation of numerous holes (via 4HF + SiO2 = SiF4↑+ 2 H2O) during the carbonization process by annealing in Ar at 800 °C, leading to the formation of holely structure and the suppression of the anatase-to-rutile phase transformation. When employed as anode materials for AIBs, the A-TiO2 @HCNFs exhibit a high sodium storage capacity of 206.8 mAh g−1 at 1.0 A g−1 after 500 cycles and a superior rate performance of 188.4 mAh g−1 at 5.0 A g−1, and a lithium storage capacity is 354.0/233.9 mAh g−1 at 0.2/1.0 A g−1 after 100/500 cycles with an excellent rate performance of 145.6 mAh g−1 at 5.0 A g−1. The superior electrochemical performance is related to the unique structure with integration of ultrafine anatase TiO2 nanoparticles and holely carbon nanofibers, which bring many advantages including improved electrical conductivity, sufficient reaction sites and robust structure stability.

Graphene-mediated dense integration of Ti3C2Tx MXene monoliths for compact energy storage: Balancing kinetics and packing density

MXenes have received intensive attraction as new anode materials for alkaline-ion batteries because of their exceptional physical and chemical characteristics. Nevertheless, the extremely low packing density hinders their practical application. Herein, we report highly dense Ti3C2Tx MXene monoliths with hierarchical porous structure involving a graphene-assisted hydrothermal method followed by capillary evaporation. The packing density is as high as 1.67 g cm−3, which is 107 times larger than that of MXene aerogel. Owing to the efficient electron and ion transport pathways as well as high packing density, the MXene monoliths exhibit high gravimetric capacity (372 mAh g−1), volumetric capacity (621 mAh cm−3), and outstanding cycling stability when tested against Li. For anode of sodium-ion battery, the as-obtained Ti3C2Tx monoliths achieve a volumetric capacity of 270 mAh cm−3. Meanwhile, a charge capacity of 167 mAh cm−3 at 0.5 A g−1 can be retained after 2000 cycles with a capacity retention of 96.5 %. This strategy is effective for preparation of high volumetric MXenes-based anode materials for compact energy storage applications.

High-Entropy NASICON Phosphates (Na3M2(PO4)3 and NaMPO4Ox, M = Ti, V, Mn, Cr, and Zr) for Sodium Electrochemistry.

High-entropy materials, with complex compositions and unique cocktail characteristics, have recently drawn significant attention. Additionally, a family of sodium super ion conductors (NASICONs)-structured phosphates in energy storage areas shows a comprehensive application for traditional alkaline ion batteries and, in particular, solid-state electrolytes. However, there is no precedent in fabricating this kind of NASICON-type high-entropy phase. Here, we report the successful fabrication of two well-crystallized high-entropy phosphates, namely, Na3(Ti0.2V0.2Mn0.2Cr0.2Zr0.2)2(PO4)3 (HE-N3M2P3) and Na(Ti0.2V0.2Mn0.2Cr0.2Zr0.2)2PO4Ox (HE-NMP). The prepared materials in which the transition metals (TMs) of Ti, V, Mn, Cr, and Zr occupy the same 12c Wykoff position can form a structure analogous to R3̅c Na3V2(PO4)3 that is carefully determined by X-ray diffraction, neutron diffraction, and transmission electron microscopy. Further, their performance for sodium ion batteries and sodium-based solid-state electrolytes was evaluated. The HE-N3M2P3 might exhibit a promising electrochemical performance for sodium storage in terms of its structure resembling that of Na3V2(PO4)3. Meanwhile, the HE-NMP shows considerable electrochemical activity with numerous broad redox ranges during extraction and insertion of Na+, related to the coexistence of several TM elements. The evaluated temperature-dependent ionic conductivity for HE-NMP solid electrolyte varies from 10-6 to 10-5 S cm-1 from room temperature to 398.15 K, offering high potential for energy storage applications as a new high-entropy system.

Atomic layer deposition of alumina onto yolk-shell FeS/MoS2 as universal anodes for Li/Na/K-Ion batteries

Transition metal sulfides are regarded as a category of promising electrodes for alkaline ion batteries because of their high theoretical capacities, fast ionic conductivity and low cost, but they also face many challenges on large volume changes, sluggish kinetics and instability of solid electrolyte interphase (SEI). To tackle these issues, this work designs iron sulfide/molybdenum disulfide (FeS / MoS2) yolk-shell sphere electrodes coated by few-nanometer thick alumina film. Such alumina film is adopted to minimize side reactions, promote the formation of stable SEI, and enhance the mechanical stability of the electrode. Specifically, when used as anode materials at 100 mA g−1 in Li/Na/K-ion batteries, the coated electrode (ALD-40-E) can deliver reversible capacities of 1007, 570 and 367 mAh g−1 after 100 cycles, respectively, which are substantially larger than those of bare FeS / MoS2 electrode (ALD-0-E: 538, 311 and 213 mAh g−1) and FeS / MoS2 with direct alumina coating on powder surface (ALD-40-P: 429, 116 and 86 mAh g−1). Good electrochemical properties are mainly ascribed to the yolk-shell structure, and the alumina thin film on the electrode, which work synergistically to maintain the electrical contact, facilitate the ion/electron diffusion paths, accommodate volume change and preserve structural stability.

Ti3C2Tx MXene compounds for electrochemical energy storage

Since their discovery in 2011, MXene compounds, and in particular the Ti3C2-based phases, have gained increasing interest from researchers leading to over 2000 scientific works in 2020. The peculiar morphological, charge transport, and surface properties make the MXenes ideal materials for energy storage applications such as active material in alkaline ion batteries and supercapacitors, as conductive or buffer agent in composite electrodes for high energy applications, and as electrocatalytic materials for oxygen evolution or redox flow batteries. Among this almost endless literature, this work focuses on 5 recent articles (2019/2020) that summarize the potential of MXenes in different energy storage applications, also resuming the most promising preparatory routes regarding industrial scalability.

Voltage-Modulated Structure Stress for Enhanced Electrochemcial Performances: The Case of μ-Sn in Sodium-Ion Batteries.

Alloy-type anodes in alkaline ion batteries have to face the challenges of huge volume change and giant structure strain/stress upon cycling. Here, reducing the structure stress for advanced performances by voltage regulation is demonstrated by using microsized Sn (μ-Sn) for sodium ion batteries as a model. Density functional theory and finite element analysis indicate that Sn/NaSn3 is the crucial phase transition highly responsible for inducing surface cracks, particle aggregations, and cell failures. Eliminating this phase transition by the control of cutoff voltages successfully extends the cycle life of μ-Sn to 2500 cycles at 2 A g-1, much longer than ∼40 cycles in a regular voltage window. The specific capacity is still retained at ∼455 mAh g-1, leading to a capacity decay of only ∼0.0088% per cycle. The results provide a simple way to achieve the outstanding performances without complicated preparation, expensive reagents, and laborious processing.

Integrating amorphous vanadium oxide into carbon nanofibers via electrospinning as high-performance anodes for alkaline ion (Li+/Na+/K+) batteries

To explore advanced anode materials with superior Li+/Na+/K+ storage performances for alkaline ion batteries (AIBs), a hybrid of amorphous vanadium oxide uniformly embedded into the highly defective carbon nanofibers (denoted as VOx@CNFs) was fabricated via a facile electrospinning method followed by proper heat treatment in this work. The integrated structure synergistically combines the advantages of the amorphous VOx and the defective carbon matrices, which can not only bring abundant active sites for ion storage and multi-channels for ion diffusion, but also well accommodate the structural change induced electrode pulverization. When evaluated as anode materials for AIBs, the optimized VOx@CNFs demonstrate excellent alkaline ion storage performances with high-specific capacities, long-cycling life and high-rate capabilities, delivering a Na+ storage capacity of 260 mAh g−1 at 1.0 A g−1 after 1000 cycles, a Li+ storage capacity of 556 mAh g−1 at 0.5 A g−1after 500 cycles, and a K+ storage capacity of 198 mAh g−1 at 0.5 A g−1 after 400 cycles.

A NiO/NiS2 nanosheet integrated electrode for high area specific capacity alkaline metal battery

Promoting in-situ growth on the Ni foam to form an integrated electrode could prove useful for improving the area-specific capacity and adhesion between the collector and active material. Here, a NiO/NiS2 nanosheet integrated electrode was designed and obtained by a hydrothermal method. The integrated electrode consisted of a mixture of NiS2 and NiO and was in the form of a nanosheet. The electrode showed high area-specific capacities as the anode for alkaline ion batteries and could achieve 1.51 (150th cycle), 0.93 (100th cycle), and 0.11 mAh•cm−2 (30th cycle) for Li+/Na+/K+ storage.

Sulfur-Deficient Porous SnS2-x Microflowers as Superior Anode for Alkaline Ion Batteries.

SnS2 as a high energy anode material has attracted extensive research interest recently. However, the fast capacity decay and low rate performance in alkaline-ion batteries associated with repeated volume variation and low electrical conductivity plague them from practical application. Herein, we propose a facile method to solve this problem by synthesizing porous SnS2 microflowers with in-situ formed sulfur vacancies. The flexible porous nanosheets in the three-dimensional flower-like nanostructure provide facile strain relaxation to avoid stress concentration during the volume changes. Rich sulfur vacancies and porous structure enable the fast and efficient electron transport. The porous SnS2−x microflowers exhibit outstanding performance for lithium ion battery in terms of high capacity (1375 mAh g−1 at 100 mA g−1) and outstanding rate capability (827 mA h g−1 at high rate of 2 A g−1). For sodium ion battery, a high capacity (~522 mAh g−1) can be achieved at 5 A g−1 after 200 cycles for SnS2−x microflowers. The rational design in nanostructures, as well as the chemical compositions, might create new opportunities in designing the new architecture for highly efficient energy storage devices.