Search Results (112)

The development of anode-free sodium metal batteries (AFSMBs) offers a promising pathway to achieve ultrahigh energy density and cost efficiency inherent to conventional sodium ion/metal batteries. However, irreversible Na plating/stripping and dendritic growth remain critical barriers. Herein, we demonstrate that separator engineering is a pivotal strategy for stabilizing AFSMBs. Through systematic evaluation of four separators—2500 separator (PP), 2325 separator (PP/PE/PP), glass fiber (GF), and an Al₂O₃-coated PE membrane, we reveal that the Al₂O₃-coated separator uniquely enables exceptional interfacial kinetics and morphological control. Na||Na symmetric cells with Al₂O₃ coated separator exhibit ultralow polarization (4.5 mV) and the highest exchange current density (1.77 × 10⁻² mA cm⁻²), while the anode-free AlC-NFPP full cells retain 91.6% capacity after 150 cycles at 2C. Specifically, the Al₂O₃ coating homogenizes Na⁺ flux, promotes dense and planar Na deposition, and facilitates near-complete stripping with minimal “dead Na”. This work establishes ceramic-functionalized separators as essential enablers of practical high-energy AFSMBs. Full article

All-solid-state anode-free sodium batteries present a special and especially important kind of energy storage device. Unfortunately, the industrial production of such batteries has been absent up to now, although the prospects of their development seem to be rather optimistic. The present mini review considers the fundamental advantages of all-solid-state anode-free sodium batteries as well as challenges in their creation. The advantages of all-solid-state anode-free sodium batteries reveal themselves when comparing them with ordinary sodium-ion batteries, sodium metal batteries, sodium batteries with liquid electrolyte, and their lithium counterparts. Full article

This study focuses on the design and optimization of a monopolar electrode configuration for the hybrid electrochemical treatment of real washing machine wastewater. A combined electrocoagulation (EC) and electro-oxidation (EO) system was optimized to maximize pollutant removal efficiency while minimizing energy consumption. The monopolar setup employed mixed metal oxide (MMO) and aluminum anodes, along with a stainless steel cathode, operating under controlled conditions with sodium chloride as the supporting electrolyte. An applied current density of 15 mA cm⁻² achieved 90% chemical oxygen demand (COD) removal, 98% surfactant degradation, complete turbidity reduction within 120 min, and pH stabilization near 8. Additionally, electrochemical disinfection achieved <2 MPN/100 mL, with no detectable phenols and the presence of organic anions such as oxalate and acetate. These results demonstrate the effectiveness of an optimized monopolar EC–EO system as a cost-efficient and sustainable strategy for wastewater treatment and potential water reuse. Further studies should focus on refining energy consumption and monitoring reaction by-products to enhance large-scale applicability. Full article

Cobalt telluride (CoTe₂) is considered an advanced anode material for sodium-ion batteries (SIBs) because of its high theoretical capacity and high conductivity. Nevertheless, the ionic radius of the Co²⁺ ion (0.74 Å) is smaller than that of the Na⁺ ion, meaning the integrity of CoTe₂ electrodes can be easily damaged when Na⁺ ions diffuse into CoTe₂ and convert to large Na₂Te. Herein, we propose a doping strategy by introducing an unreactive element but with a large radius to enhance the overall performance. Lanthanum (La) can be doped into the CoTe₂ structure to counteract the size effect of Na₂Te since La has a large radius. On the other hand, La with abundant electrons in CoTe₂ can also facilitate the charge transfer during charge/discharge. As a result, La-doped CoTe₂ (La-CoTe₂) can deliver a maximum capacity of 345 mAh g⁻¹ at 0.05 A g⁻¹ and has a decent rate performance. After 2000 cycles at 2 A g⁻¹, a capacity of 88 mAh g⁻¹ remained, which is a notable improvement compared to undoped CoTe₂. These results demonstrate the potential of rare earth elements in preparing advanced SIB electrode materials. Full article

Metal sulfides are promising anode candidates for sodium–ion batteries (SIBs) due to their high theoretical capacities. However, their practical application is limited by significant volume extension and sluggish Na⁺ diffusion during cycling, which lead to rapid capacity degradation and poor long-term stability. In this work, we report the rational design of a hollow triple-shelled high-entropy sulfide (NaFeZnCoNiMn)₉S₈, synthesized through sequential templating method under hydrothermal conditions. Transmission electron microscopy confirms its well-defined three-shelled architecture. The inter-shell voids effectively buffer Na⁺ insertion/desertion-induced volume extension, while the tailored high-entropy matrix enhances electronic conductivity and accelerates Na⁺ transport. This synergistic design yields outstanding performance, including a high initial Coulombic efficiency (ICE) of 94.1% at 0.1 A g⁻¹, low charge-transfer resistance (0.32~2.54 Ω), fast Na⁺ diffusion efficiency (10^−8.5–10^−10.5 cm² s⁻¹), and reversible capacity of 582.6 mAh g⁻¹ after 1600 cycles at 1 A g⁻¹ with 91.2% capacity retention. These results demonstrate the potential of high-entropy, multi-shelled architectures as a robust platform for next-generation durable SIB anodes. Full article

Sodium-ion batteries present an economical energy storage solution, yet their anode kinetics remain slow, impeding rate performance and cyclability. Layered FeSe anodes, characterized by metallic conductivity, hold potential, but structural decay and insufficient active sites during cycling continue to pose challenges. Herein, these challenges are addressed through the implementation of dual Ni doping and Se vacancy engineering in FeSe@C to synergistically regulate cationic/anionic configurations. The ionic substitution of larger Fe²⁺ ions (0.78 Å ionic radius) with smaller Ni²⁺ ions (0.69 Å) induces lattice distortion and generates abundant Se vacancies, enhancing electron transport, active site accessibility, and Na⁺ adsorption. These synergistic modifications effectively boost Na⁺ diffusion kinetics and electrolyte compatibility, creating a favorable electrochemical environment for fast sodium storage. Consequently, the optimized 2%Ni-FeSe@C electrode retains an exceptional discharge specific capacity of 307.67mAh g⁻¹ after 1000 cycles at an ultrahigh current density of 5 Ag⁻¹, showcasing superior rate capability and long-term cycling stability, paving the way for practical high-power SIBs. Full article

Sodium metal is a promising anode material for sodium metal batteries (SMBs) due to its high theoretical specific capacity and low electrochemical potential. However, its practical implementation is severely limited by dendrite formation, which causes short circuits and safety issues. Here, we introduce a separator modification strategy using Ag nanoparticles decorated with two-dimensional diamane on a commercial polypropylene (PP) substrate (Ag-diamane/PP) to enhance the performance of sodium metal anodes (SMAs). The synergistic effect between the sodiophilic Ag nanoparticles and the diamane network not only accelerates Na⁺ transport through the modified separator but also reduces interfacial resistance. This dendrite-suppression effect was systematically validated using in situ optical microscopy and ex situ scanning electron microscopy. Symmetric Na||Na cells incorporating the Ag-diamane/PP separator exhibit exceptional cycling stability, maintaining more than 3800 h of operation at 2 mA cm⁻² with a capacity of 1 mAh cm⁻². Furthermore, a full-cell configuration with a Na₃V₂(PO₄)₃@C cathode, Ag-diamane/PP separator, and Na metal anode delivers a high reversible capacity of 94.35 mAh g⁻¹ and stable cycling for 270 cycles. This work highlights the Ag-diamane/PP separator as a promising solution for advancing dendrite-free SMBs with long-term cycling stability and high energy density. Full article

Sodium-ion batteries (SIBs) share similar working principles with lithium-ion batteries while demonstrating cost advantages. However, the current understanding of their safety characteristics remains insufficient, and the thermal runaway mechanisms of different SIB systems have not been fully elucidated. This study investigated the following two mainstream sodium-ion battery systems: polyanion-type compound (PAC) and layered transition metal oxide (TMO) cathodes. Differential scanning calorimetry (DSC) was employed to evaluate the thermal stability of cathodes and anodes, examining the effects of state of charge (SOC), cycling, and overcharging on electrode thermal stability. The thermal stability of electrolytes with different compositions was also characterized and analyzed. Additionally, adiabatic thermal runaway tests were conducted using an accelerating rate calorimeter (ARC) to explore temperature–voltage evolution patterns and temperature rise rates. The study systematically investigated heat-generating reactions during various thermal runaway stages and conducted a comparative analysis of the thermal runaway characteristics between these two battery systems. Full article

Transition metal selenides are considered one of the most promising materials for sodium-ion battery anodes due to their excellent theoretical capacity. However, it remains challenging to suppress the volume variation and the resulted capacity decay during the charge–discharge process. Herein, hollow-structured CoNiSe₂ dual transition metal selenides wrapped in a carbon shell (HS-Co_xNi_ySe₂@C) were deliberately designed and prepared through sequential coating of polyacrylonitrile (PAN), ion exchange of ZIF-67 with Ni²⁺ metal ions, and carbonization/selenization. The hollow structure was evidenced by transmission electron microscopy, and the crystalline structure was confirmed by X-ray diffraction. The ample internal space of HS-Co_xNi_ySe₂@C effectively accommodated volume expansion during the charge and discharge processes, and the large surface area enabled sufficient contact between the electrode and electrolyte and shortened the diffusion path of sodium ions for a feasible electrochemical reaction. The surface area and ionic conductivity of HS-Co_xNi_ySe₂@C were strongly dependent on the ratio of Co to Ni. The synergistic effect between Co and Ni enhanced the conductivity and electron mobility of HS-Co_xNi_ySe₂@C, thereby improving charge transfer efficiency. By taking into account the structural advantages and rational metal selenide ratios, significant improvements can be achieved in the cycling performance, rate performance, and overall electrochemical stability of sodium-ion batteries. The optimized HS-Co_xNi_ySe₂@C demonstrated excellent performance, and the reversible capacity remained at 334 mAh g⁻¹ after 1000 cycles at a high current of 5.0 A g⁻¹. Full article

Sodium–ion batteries are emerging as strong competition to lithium–ion batteries in certain market sections. While these cells do not use critical raw materials, they still feature a liquid electrolyte with all its inherent safety issues, like high flammability and toxicity. Alternative concepts like oxide-ceramic-based all-solid-state batteries feature the highest possible safety while still maintaining competitive electrochemical performance. However, production technologies are still in their infancy, especially for Na all-solid-state batteries, and need to be urgently developed to enable solid-state-battery technology using only abundant raw materials. In this study, the additive-free production of freestanding, undoped NaSICON separators via tape-casting is demonstrated, having an extremely high total Na-ion conductivity of up to 2.44 mS·cm⁻¹ at room temperature. Nevertheless, a strong influence of sample thickness on phase purity as well as electrochemical performance is uncovered. Additionally, the effect of self-coating of NaSICON during high-temperature treatment was evaluated as a function of thickness. While advantageous for increasing the stability against Na-metal anodes, detrimental consequences are identified when separator thickness is reduced to industrially relevant values and mitigation measures are postulated. Full article

With the growing market of secondary batteries for electric vehicles (EVs) and grid-scale energy storage systems (ESS), driven by environmental challenges, the commercialization of sodium-ion batteries (SIBs) has emerged to address the high price of lithium resources used in lithium-ion batteries (LIBs). However, achieving competitive energy densities of SIBs to LIBs remains challenging due to the absence of high-capacity anodes in SIBs such as the group-14 elements, Si or Ge, which are highly abundant in LIBs. This review presents potential candidates in metal pnictogenides as promising anode materials for SIBs to overcome the energy density bottleneck. The sodium-ion storage mechanisms and electrochemical performance across various compositions and intrinsic physical and chemical properties of pnictogenide have been summarized. By correlating these properties, strategic frameworks for designing advanced anode materials for next-generation SIBs were suggested. The trade-off relation in pnictogenides between the high specific capacities and the failure mechanism due to large volume expansion has been considered in this paper to address the current issues. This review covers several emerging strategies focused on improving both high reversible capacity and cycle stability. Full article

The development of metal sulfides as anodes for sodium-ion batteries (SIBs) is significantly obstructed by the slow kinetics of the electrochemical reactions and the substantial volume changes on the cycling. Herein, we introduce a selenium-substituted cobalt disulfide embedded within a dual carbon–graphene framework (Se-CoS₂/C@rGO) for high-performance SIBs. The Se-CoS₂/C@rGO was prepared via a synchronous sulfurization/selenization strategy using Co-alkoxide as the precursor and SeS₂ as the source of selenium and sulfur, during which the EG anions are converted in situ to a S, Se codoped carbon scaffold. The dual carbon–graphene matrix not only improves the electronic conductivity but also stabilizes the electrode material effectively. In addition, the Se substitution within the CoS₂ lattice further improves the electrical conductivity and promotes the Na⁺ reaction kinetics. The enhanced intrinsic electronic/ionic conductivity and reinforced structural stability endow the Se-CoS₂/C@rGO anode with a high reversible capacity (558.2 mAh g⁻¹ at 0.2 A g⁻¹), superior rate performance (351 mAh g⁻¹ at 20 A g⁻¹), and long cycle life (93.5% capacity retention after 2100 cycles at 1 A g⁻¹). This work provides new insights into the development of stable and reversible anode materials through Se substitution and dual carbon encapsulation. Full article

Iron phosphide (FeP) represents a promising anode material for sodium-ion batteries, attributed to its significant theoretical capacity, moderate operating potential, and natural abundance. However, due to the low conductivity and significant volume expansion of FeP electrodes, their specific capacity and cycle life decrease rapidly during charging and discharging. In this study, we synthesized FeP nanoparticles supported on a three-dimensional porous carbon framework composite (FeP@PCF) using a straightforward colloidal blow molding method, employing iron nitrate nonahydrate and polyvinylpyrrolidone as raw materials. The nanoscale size of the FeP particles, along with the abundant mesopores and high specific surface area of the 3D porous carbon framework, contribute to the impressive sodium storage performance of FeP@PCF. It is revealed that FeP@PCF achieves a remarkable capacity of 196.6 mA h g⁻¹ at a current density of 1.0 A g⁻¹. Furthermore, after 800 cycles at this current density, it retains a capacity of 172.4 mA h g⁻¹, demonstrating excellent cycling performance. Kinetic and dynamic studies indicate that this exceptional performance is largely attributed to the well-designed FeP@PCF, which exhibits a high capacitive contribution of 88.3% at a scan rate of 1 mV s⁻¹. Full article

Room-temperature sodium–sulfur (RT Na–S) batteries offer a superior, high-energy-density solution for rechargeable batteries using earth-abundant materials. However, conventional RT Na–S batteries typically use sulfur as the cathode, which suffers from severe volume expansion and requires pairing with a sodium metal anode, raising significant safety concerns. Utilizing Na₂S as the cathode material addresses these issues, yet challenges such as Na₂S’s low conductivity as well as the shuttle effect of polysulfide still hinder RT Na–S battery development. Herein, we present a simple and cost-effective method to fabricate a Na₂S–Na₆CoS₄/Co@C cathode, wherein Na₂S nanoparticles are embedded in a conductive carbon matrix and coupled with dual catalysts, Na₆CoS₄ and Co, generated via the in situ carbothermal reduction of Na₂SO₄ and CoSO₄. This approach creates a three-dimensional porous composite cathode structure that facilitates electrolyte infiltration and forms a continuous conductive network for efficient electron transport. The in situ formed Na₆CoS₄/Co electrocatalysts, tightly integrated with Na₂S, exhibit strong catalytic activity and robust physicochemical stabilization, thereby accelerating redox kinetics and mitigating the polysulfide shuttle effect. As a result, the Na₂S–Na₆CoS₄/Co@C cathode achieves superior capacity retention, demonstrating a discharge capacity of 346 mAh g⁻¹ after 100 cycles. This work highlights an effective strategy for enhancing Na₂S cathodes with embedded catalysts, leading to enhanced reaction kinetics and superior cycling stability. Full article

To address large volumetric expansion and low conductivity of bismuth-based anodes, an ion-replacement technique is proposed to prepare Bi/C composites, using 1,3,5-benzenetricarboxylicacid (H₃BTC) based metal–organic framework as precursors. The characterizations reveal that the Bi/C composite derived from Cu-H₃BTC is a sheet structure with the size of 150 nm, and Bi nanoparticles are uniformly dispersed in carbon sheets. When assessed as anode material for sodium ion batteries (SIBs), a sheet-like Bi/C anode exhibits superior sodium storage performance. It delivers a reversible capacity of 254.6 mAh g⁻¹ at 1.0 A g⁻¹ after 100 cycles, and the capacity retention is high at 91%. Even at 2.0 A g⁻¹, the reversible capacity still reaches 242.8 mAh g⁻¹. The efficient sodium storage performance benefits from the uniform dispersion of Bi nanoparticles in the carbon matrix, which not only provides abundant active sites but also alleviates the volume expansion. Meanwhile, porous carbon sheets can increase the electrical conductivity and accelerate the electrochemical reaction kinetics. Full article