CoS2/carbon network flexible film with Co-N bond/π-π interaction enables superior mechanical properties and high-rate sodium ion storage

Flexible electrodes based on conversion-type materials have potential applications in low-cost and high-performance flexible sodium-ion batteries (FSIBs), owing to their high theoretical capacity and appropriate sodiation potential. However, they suffer from flexible electrodes with poor mechanical properties and sluggish reaction kinetics. In this study, freestanding CoS2 nanoparticles coupled with graphene oxides and carbon nanotubes (CoS2/GO/CNTs) flexible films with robust and interconnected architectures were successfully synthesized. CoS2/GO/CNTs flexible film displays high electronic conductivity and superior mechanical properties (average tensile strength of 21.27 MPa and average toughness of 393.18 KJ m-3) owing to the defect bridge for electron transfer and the formation of the π-π interactions between CNTs and GO. In addition, the close contact between the CoS2 nanoparticles and carbon networks enabled by the Co-N chemical bond prevents the self-aggregation of the CoS2 nanoparticles. As a result, the CoS2/GO/CNTs flexible film delivered superior rate capability (213.5 mAh g-1 at 6 A g-1, better than most reported flexible anode) and long-term cycling stability. Moreover, the conversion reaction that occurred in the CoS2/GO/CNTs flexible film exhibited pseudocapacitive behavior. This study provides meaningful insights into the development of flexible electrodes with superior mechanical properties and electrochemical performance for energy storage.

Sulfur-doped carbonized bacterial cellulose as a flexible binder-free 3D anode for improved sodium ion storage

Carbon-based materials have received wide attention as electrodes for energy storage and conversion owing to their rapid mass transfer processes, outstanding electronic conductivities, and high stabilities. Here, sulfur-doped carbonized bacterial cellulose (S-CBC) was prepared as a high-performance anode for sodium-ion batteries (SIBs) by simultaneous carbonization and sulfidation using the bacterial cellulose membrane produced by microbial fermentation as the precursor. Doping sublimed sulfur powder into CBC results in a greater degree of disorder and defects, buffering the volume expansion during the cycle. Significantly, the three-dimensional (3D) network structure of bacterial cellulose endows S-CBC with flexible self-support. As an anode for sodium ion batteries, S-CBC exhibits a high specific capacity of 302.9 mA h g-1 at 100 mA g-1 after 50 cycles and 177.6 mA h g-1 at 2 A g-1 after 1000 cycles. Compared with the CBC electrode, the S-CBC electrode also exhibits enhanced rate performance in sodium storage. Moreover, theoretical simulations reveal that Na+ has good adsorption stability and a faster diffusion rate in S-CBC. The doping of the S element introduces defects that enlarge the interlayer distance, and the synergies of adsorption and bonding are the main reasons for its high performance. These results indicate the potential application prospects of S-CBC as a flexible binder-free electrode for high-performance SIBs.

Synthesis of Sb-pyromellitic acid metal-organic framework material and its sodium storage properties

Developing electrode materials with high capacity and low cost is crucial for promoting the application of sodium-ion batteries. In this paper, a new Sb-PMA-300 metal-organic framework (MOF) material is synthesized by chelation of Sb³⁺ and pyromellitic acid (PMA) followed by a heat treatment at 300 °C. As anodes for sodium-ion batteries, the Sb-PMA-300 composite exhibits a stable capacity of 443 mA h g^-1 at a current density of 0.1 A g^-1. At a current density of 1 A g^-1, the discharge capacity is maintained at 326.4 mA h g^-1 after 200 cycles. The electrode process dynamics of this material are mainly controlled by diffusion. The values of the diffusion coefficient of Na⁺ are between 10^-12 and 3.0 × 10^-10 cm² s^-1 during discharging, while they are between 10^-12 and 5.0 × 10^-11 cm² s^-1 during charging. The excellent cycle stability is attributed to the special structure of the MOF material, where the organic ligand prevents the aggregation of Sb alloy particles and buffers the tension resulting from volume variation.

Deciphering the Sb4O5Cl2-MXene Hybrid as a Potential Anode Material for Advanced Potassium-Ion Batteries

Potassium-ion batteries (PIBs) possess great potential in new-generation large-scale energy storage. However, their applications are plagued by large volume change and sluggish reaction kinetics of the electrode materials during the repeated charge/discharge processes. Guided by computerization modeling, we, herein, report the atomic-scale interfacial regulation of Sb₄O₅Cl₂ coupled with structural engineering for the robust anode material of PIBs via simple MXene hybridization using a microwave-assisted hydrothermal method. Benefiting from the ostensive interfacial interplay between Sb₄O₅Cl₂ and Ti₃C₂, MXene hybridization induces a favorable variation in spin polarization densities and the coordination of Sb atoms in Sb₄O₅Cl₂, which are effective in optimizing the K⁺ ion diffusion path, thus resulting in a significantly reduced K⁺ ion diffusion barrier and promoted K⁺ insertion/extraction kinetics. The as-prepared Sb₄O₅Cl₂-MXene anodes exhibit a highly reversible discharge capacity and decent cyclability, in addition to the low discharge plateau and promising full cell performance. This work is pivotal for not only paving the way for the exploration of anode materials for high-performance PIBs but also shedding light on the fundamental research on K⁺ ion storage in antimony oxychloride.

Conversion-Alloying Anode Materials for Sodium Ion Batteries

The past decade has witnessed a rapidly growing interest toward sodium ion battery (SIB) for large-scale energy storage in view of the abundance and easy accessibility of sodium resources. Key to addressing the remaining challenges and setbacks and to translate lab science into commercializable products is the development of high-performance anode materials. Anode materials featuring combined conversion and alloying mechanisms are one of the most attractive candidates, due to their high theoretical capacities and relatively low working voltages. The current understanding of sodium-storage mechanisms in conversion-alloying anode materials is presented here. The challenges faced by these materials in SIBs, and the corresponding improvement strategies, are comprehensively discussed in correlation with the resulting electrochemical behavior. Finally, with the guidance and perspectives, a roadmap toward the development of advanced conversion-alloying materials for commercializable SIBs is created.

Oxygen-rich interface enables reversible stibium stripping/plating chemistry in aqueous alkaline batteries

Aqueous alkaline batteries see bright future in renewable energy storage and utilization, but their practical application is greatly challenged by the unsatisfactory performance of anode materials. Herein, we demonstrate a latent Sb stripping/plating chemistry by constructing an oxygen-rich interface on carbon substrate, thus providing a decent anode candidate. The functional interface effectively lowers the nucleation overpotential of Sb and strengthens the absorption capability of the charge carriers (SbO₂⁻ ions). These two advantageous properties inhibit the occurrence of side reactions and thus enable highly reversible Sb stripping/plating. Consequently, the Sb anode delivers theoretical-value-close specific capacity (627.1 mA h g⁻¹), high depth of discharge (95.0%) and maintains 92.4% coulombic efficiency over 1000 cycles. A robust aqueous NiCo₂O₄//Sb device with high energy density and prominent durability is also demonstrated. This work provides a train of thoughts for the development of aqueous alkaline batteries based on Sb chemistry.

The practical application of aqueous alkaline battery is confined by limited choice of anode. Here, the authors demonstrate an oxygen-rich interface induced reversible Sb stripping/plating chemistry that provides a promising Sb metal anode with fast reaction kinetics and favourable stability.

Dual metal oxides interconnected by carbon nanotubes for high-capacity Li- and Na-ion batteries

Sb₂O₃ and Co₃O₄ as potential anode materials for Li- and Na-ion batteries exhibit high theoretical capacities and excellent electrochemical stability; however, volume expansion, exfoliation and poor electronic conductivity affect the electrochemical performance to some extent. Here, we design dual metal oxide hybrid composites by one- and two-step solvothermal processes, in which Co₃O₄ with Sb₂O₃ traps Li⁺ ions and carbon nanotubes (CNTs) as a network guarantee for electron transport. Sb₂O₃/CNTs/Co₃O₄ and Sb₂O₃/Co₃O₄/CNTs composites exhibit different morphologies, particles sizes and Li⁺/Na⁺ storage performance. The Sb₂O₃/CNTs/Co₃O₄ composite showes initial capacities of 1790 and 1450 mAh g^-1 after 100 cycles as the anode for a Li-ion battery. The capacity retention of the Sb₂O₃/Co₃O₄/CNTs composite is better than the Sb₂O₃/CNTs/Co₃O₄ composite for Na-ion storage. With charge/discharge cycles, the transition reaction of Sb₂O₃ and Co₃O₄ to Sb and Co repeats, leading to a homogenous distribution in CNTs and further growth of the nanoparticles. This work provides new insights into the design of high-capacity anodes for Li- and Na-ion storage by adjusting their composition and morphology.

Flexible 3D carbon cloth as a high-performing electrode for energy storage and conversion

High-performance energy storage and conversion devices with high energy density, power density and long-term cycling life are of great importance in current consumer electronics, portable electronics and electric vehicles. Carbon materials have been widely investigated and utilized in various energy storage and conversion devices due to their excellent conductivity, mechanical and chemical stability, and low cost. Abundant excellent reviews have summarized the most recent progress and future outlooks for most of the current prime carbon materials used in energy storage and conversion devices, such as carbon nanotubes, fullerene, graphene, porous carbon and carbon fibers. However, the significance of three-dimensional (3D) commercial carbon cloth (CC), one of the key carbon materials with outstanding mechanical stability, high conductivity and flexibility, in the energy storage and conversion field, especially in wearable electronics and flexible devices, has not been systematically summarized yet. In this review article, we present a careful investigation of flexible CC in the energy storage and conversion field. We first give a general introduction to the common properties of CC and the roles it has played in energy storage and conversion systems. Then, we meticulously investigate the crucial role of CC in typical electrochemical energy storage systems, including lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries and supercapacitors. Following a description of the wide application potential of CC in electrocatalytic hydrogen evolution, oxygen evolution/reduction, full-water splitting, etc., we will give a brief introduction to the application of CC in the areas of photocatalytically and photoelectrochemically induced solar energy conversion and storage. The review will end with a brief summary of the typical superiorities that CC has in current energy conversion and storage systems, as well as providing some perspectives and outlooks on its future applications in the field. Our main interest will be focused on CC-based flexible devices due to the inherent superiority of CC and the increasing demand for flexible and wearable electronics.

Sb&Sb2O3@C-enhanced flexible carbon cloth as an advanced self-supporting anode for sodium-ion batteries

Sb&Sb₂O₃@C/CC prepared by a sublimation method exhibits excellent electrochemical properties when used as an anode for sodium-ion batteries.

Enhanced Electrochemical Performance of Sb2O3 as an Anode for Lithium-Ion Batteries by a Stable Cross-Linked Binder

A binder plays an important role in lithium-ion batteries (LIBs), especially for the electrode materials which have large volume expansion during charge and discharge. In this work, we designed a cross-linked polymeric binder with an esterification reaction of Sodium Carboxymethyl Cellulose (CMC) and Fumaric Acid (FA), and successfully used it in an Sb2O3 anode for LIBs. Compared with conventional binder polyvinylidene fluoride (PVDF) and CMC, the new cross-linked binder improves the electrochemical stability of the Sb2O3 anode. Specifically, with CMC-FA binder, the battery could deliver ~611.4 mAh g−1 after 200 cycles under the current density of 0.2 A g−1, while with PVDF or CMC binder, the battery degraded to 265.1 and 322.3 mAh g−1, respectively. The improved cycling performance is mainly due to that the cross-linked CMC-FA network could not only efficiently improve the contact between Sb2O3 and conductive agent, but can also buffer the large volume charge of the electrode during repeated charge/discharge cycles.

Manipulating irreversible phase transition of NaCrO2 towards an effective sodium compensation additive for superior sodium-ion full cells

During the first charge process of full cells, a solid electrolyte interphase (SEI) film is formed when the active ion from the cathode is consumed, resulting in irreversible capacity loss. This phenomenon has shown to be more serious in sodium-ion full cells than in lithium-ion full cells. Although many strategies have been employed to alleviate the loss of sodium ions, such as presodiation and construction of an artificial solid electrolyte interface, they are both cumbersome and time-consuming. For the first time, NaCrO₂ was used as an effective self-sacrificing sodium compensation additive in sodium-ion full cells due to the irreversible phase transition of NaCrO₂ in a high voltage region can deliver an irreversible capacity of up to 230 mAh g^-1. Based on this design, sodium-ion full cells coupled with hard carbon as the anode exhibited higher capacity, less polarization, greater energy density, and superior cycle stability than those of a pristine electrode. This is mainly attributed to the removal of sodium ions from NaCrO₂, which compensates for the loss of sodium ions consumed during the formation of the SEI film on the anode surface during the first charge process. Overall, this work opens up a new avenue for exploring sodium compensation strategy and contributing to practical application of sodium-ion full cells.

High Volumetric and Gravimetric Capacity Electrodeposited Mesostructured Sb2 O3 Sodium Ion Battery Anodes

Sodium ion batteries (SIBs) are considered promising alternatives to lithium ion batteries for grid-scale and other energy storage applications because of the broad geographical distribution and low cost of sodium relative to lithium. Here, fabrication and characterization of high gravimetric and volumetric capacity 3D Ni-supported Sb₂ O₃ anodes for SIBs are presented. The electrodes are prepared by colloidal templating and pulsed electrodeposition followed by heat treatment. The colloidal template is optimized to provide large pore interconnects in the 3D scaffold to enable a high active materials loading and accommodate a large volume expansion during cycling. An electrodeposited loading of 1.1 g cm^-3 is chosen to enable a combined high gravimetric and volumetric capacity. At this loading, the electrodes exhibit a specific capacity of ≈445 mA h g^-1 and a volumetric capacity of ≈488 mA h cm^-3 with a capacity retention of 89% after 200 cycles at 200 mA g^-1 . The stable cycling performance can be attributed to the 3D metal scaffold, which supports active materials undergoing large volume changes, and an initial heat treatment appears to improve the adhesion of the Sb₂ O₃ to the metal scaffold.

Carbon-Based Alloy-Type Composite Anode Materials toward Sodium-Ion Batteries

In the scenario of renewable clean energy gradually replacing fossil energy, grid-scale energy storage systems are urgently necessary, where Na-ion batteries (SIBs) could supply crucial support, due to abundant Na raw materials and a similar electrochemical mechanism to Li-ion batteries. The limited energy density is one of the major challenges hindering the commercialization of SIBs. Alloy-type anodes with high theoretical capacities provide good opportunities to address this issue. However, these anodes suffer from the large volume expansion and inferior conductivity, which induce rapid capacity fading, poor rate properties, and safety issues. Carbon-based alloy-type composites (CAC) have been extensively applied in the effective construction of anodes that improved electrochemical performance, as the carbon component could alleviate the volume change and increase the conductivity. Here, state-of-the-art CAC anode materials applied in SIBs are summarized, including their design principle, characterization, and electrochemical performance. The corresponding alloying mechanism along with its advantages and disadvantages is briefly presented. The crucial roles and working mechanism of the carbon matrix in CAC anodes are discussed in depth. Lastly, the existing challenges and the perspectives are proposed. Such an understanding critically paves the way for tailoring and designing suitable alloy-type anodes toward practical applications.

In situ synthesis of tin dioxide submicrorods anchored on nickel foam as an additive-free anode for high performance sodium-ion batteries

A hybrid of tin dioxide submicrorods anchored on conductive nickel foam (SnO₂ submicrorods-Ni foam) is in-situ synthesized via a hydrothermal and a subsequent heat treatment by using stannic chloride and sodium hydroxide as the starting materials. Characterization results indicate that the synthesized SnO₂ submicrorods has a length of ∼400 nm and a diameter of ∼150 nm anchoring tightly on Ni foam. The electrochemical properties of the material as an additive-free anode for sodium-ion batteries are investigated. And a comparative research of the reversible sodium storage properties between the additive-free electrode of SnO₂ submicrorods-Ni foam and the additive electrode of SnO₂ rod-assembly microspheres is carried out. The results demonstrate that the SnO₂ submicrorods-Ni foam is a highly attractive anode for sodium ion batteries, which could exhibit much better sodium storage properties than the SnO₂ rod-assembly microspheres and other reported SnO₂-based additive electrodes. The excellent sodium storage properties of the SnO₂ submicrorods-Ni foam electrode can be attributed to its structure advantages without additive-assistant, which increase sodium storage active sites, facilitate the electronic/ionic transport and stabilize the total electrode structure during charge-discharge process.