Room-temperature Sodium-sulfur Batteries Research Articles

Challenge and Strategies in Room Temperature Sodium-Sulfur Batteries: A Comparison with Lithium-Sulfur Batteries.

Metal-sulfur batteries exhibit great potential as next-generation rechargeable batteries due to the low sulfur cost and high theoretical energy density. Sodium-sulfur (Na-S) batteries present higher feasibility of long-term development than lithium-sulfur (Li-S) batteries in technoeconomic and geopolitical terms. Both lithium and sodium are alkali metal elements with body-centered cubic structures, leading to similar physical and chemical properties and exposing similar issues when employed as the anode in metal-sulfur batteries. Indeed, some inspiration for mechanism researches and strategies in Na-S systems comes from the more mature Li-S systems. However, the dissimilarities in microscopic characteristics determine that Na-S is not a direct Li-S analogue. Herein, the daunting challenges derived by the differences of fundamental characteristics in Na-S and Li-S systems are discussed. And the corresponding strategies in Na-S batteries are reviewed. Finally, general conclusions and perspectives toward the research direction are presented based on the dissimilarities between both systems. This review attempts to provide important insights to facilitate the assimilation of the available knowledge on Li-S systems for accelerating the development of Na-S batteries on the basis of their dissimilarities.

V2O3-decorated carbon nanofibers as a robust interlayer for long-lived, high-performance, room-temperature sodium–sulfur batteries

We developed a V2O3 nanoparticle–decorated carbon nanofiber (V2O3@CNF) interlayer for room-temperature sodium–sulfur batteries (RT/NaSBs), inserted on the cathode side of the separator to inhibit the shuttling of sodium polysulfides, i.e., their migration to the sodium anode, and thus realize high-performance RT/NaSBs. The V2O3 adsorbs polysulfides and catalytically promotes polysulfide trapping, while the CNFs provide conductive channels that facilitate ion transport and accelerate reaction kinetics. The electrochemical performance of the resulting Na–S cells are superior to those of cells with a CNF interlayer and without an interlayer. A cell with a V2O3@CNF interlayer utilizes almost 70% of its active material at 0.1C, while cells with a CNF interlayer and without an interlayer utilize 54 and 33%, respectively. It demonstrates superior rate performance, achieving a capacity of 268 mA h g−1 at 2.0C, and its diffusion coefficient (∼10−11cm2 s−1) is an order of magnitude higher than those of cells with a CNF interlayer or without an interlayer (∼10−12 cm2 s−1), indicating fast reaction kinetics. Moreover, it delivers a discharge capacity of 406 mA h g−1 after 500 cycles at 1.0C with a high coulombic efficiency of 100%. Even at a high C-rate of 2.0C, the capacity of the cell decays at a low rate of 0.076% per cycle over 1000 cycles, indicating exceptional capacity retention. The outstanding electrochemical performance is mainly attributed to the effective sodium polysulfide confinement, improved active material utilization, and accelerated reaction kinetics associated with the V2O3@CNF interlayer.

A High-Efficiency Mo2 C Electrocatalyst Promoting the Polysulfide Redox Kinetics for Na-S Batteries.

Room-temperature sodium-sulfur (RT Na-S) batteries, as promising next-generation energy storage candidates, are drawing more and more attention due to the high energy density and abundant elements reserved in the earth. However, the native downsides of RT Na-S batteries (i.e., enormous volume changes, the polysulfide shuttle, and the insulation and low reactivity of S) impede their further application. To conquer these challenges, hierarchical porous hollow carbon polyhedrons embedded with uniform Mo2 C nanoparticles are designed deliberately as the host for S. The micro- andmesoporous hollow carbon indeed dramatically enhances the reactivity of the S cathodes andaccommodates the volume changes. Meanwhile, the highly conductive dispersed Mo2 C has a strong chemical adsorption to polysulfides and catalyzes the transformation of polysulfides, which can effectively inhibit the dissolution of polysulfides and accelerate the reaction kinetics. Thus, the as-prepared S cathode can display a high reversible capacity (1098 mAh g-1 at 0.2 A g-1 after 120 cycles) and superior rate performance (483 mAh g-1 at 10.0 A g-1 ). This work provides a new method to boost the performance of RT Na-S batteries.

Robust Room‐Temperature Sodium‐Sulfur Batteries Enabled by a Sandwich‐Structured MXene@C/Polyolefin/MXene@C Dual‐functional Separator

Room-temperature sodium-sulfur (RT-Na-S) batteries are attracting increased attention due to their high theoretical energy density and low-cost. However, the traditional RT-Na-S batteries assembled with glass fiber (GF) separators are still hindered by the polysulfide shuttle effect and sodium dendrite growth, limiting the battery's capacity and cycling stability. Here, a facile and effective method toward commercial polyolefin separators for constructing stable RT-Na-S batteries is presented. By coating commercial polypropylene membrane with core-shell structured MXene@C nanosheets, a powerful dual-functional separator with improved electrolyte wettability that can inhibit polysulfide migration and induce uniform sodium disposition is developed. More importantly, the modified separator can also accelerate the conversion kinetics of sodium polysulfides. Benefiting from these characteristics, the as-prepared RT-Na-S battery exhibits a remarkably enhanced capacity (1159 mAh g-1 at 0.2 C) and excellent cycling performance (95.8% of capacity retention after 650 cycles at 0.5 C). This study opens a promising avenue for the development of high-performance Na-S batteries.

Stable Room-Temperature Sodium-Sulfur Batteries in Ether-Based Electrolytes Enabled by the Fluoroethylene Carbonate Additive.

Because of its high energy density and low cost, the room-temperature sodium-sulfur (RT Na-S) battery is a promising candidate to power the next-generation large-scale energy storage system. However, its practical utilization is hampered by the short life span owing to the severe shuttle effect, which originates from the "solid-liquid-solid" reaction mechanism of the sulfur cathode. In this work, fluoroethylene carbonate is proposed as an additive, and tetraethylene glycol dimethyl ether is used as the base solvent. For the sulfurized polyacrylonitrile cathode, a robust F-containing cathode-electrolyte interphase (CEI) forms on the cathode surface during the initial discharging. The CEI prohibits the dissolution and diffusion of the soluble intermediate products, realizing a "solid-solid" reaction process. The RT Na-S cell exhibits a stable cycling performance: a capacity of 587 mA h g-1 is retained after 200 cycles at 0.2 A g-1 with nearly 100% Coulombic efficiency.

Continuous Carbon Channels Enable Full Na-Ion Accessibility for Superior Room-Temperature Na-S Batteries.

Porous carbon has been widely used as an efficient host to encapsulate highly active molecular sulfur (S) in Li-S and Na-S batteries. However, for these sub-nanosized pores, it is a challenge to provide fully accessible sodium ions with unobstructed channels during cycling, particularly for high sulfur content. It is well recognized that solid interphase with full coverage over the designed architectures plays critical roles in promoting rapid charge transfer and stable conversion reactions in batteries, whereas constructing a high-ionic-conductivity solid interphase in the pores is very difficult. Herein, unique continuous carbonaceous pores are tailored, which can serve as multifunctional channels to encapsulate highly active S and provide fully accessible pathways for sodium ions. Solid sodium sulfide interphase layers are also realized in the channels, showing high Na-ion conductivity toward stabilizing the redox kinetics of the S cathode during charge/discharge processes. This systematically designed carbon-hosted sulfur cathode delivers superior cycling performance (420 mAh g-1 at 2 A g-1 after 2000 cycles), high capacity retention of ≈90% over 500 cycles at current density of 0.5 A g-1 , and outstanding rate capability (470 mAh g-1 at 5 A g-1 ) for room-temperature sodium-sulfur batteries.

Two-dimensional titanium carbide (Ti3C2Tx) MXenes to inhibit the shuttle effect in sodium sulfur batteries.

Room-temperature sodium sulfur batteries (RT-NSBs) are among the promising candidates for large-scale energy storage applications because of the natural abundance of the electrode materials and impressive energy density. However, one of the main technical challenges of RT-NSBs is the shuttle effect by which active redox intermediates (i.e., sodium polysulfides Na2Sn, n = 1-8) are dissolved in electrolytes, which hamper the battery reversibility. The interfacial interplays between Na2Sn and the electrodes (or electrolytes) at the atomic level thus play an intrinsic role in elucidating the shuttle effect. This work reports the ab initio calculations to unravel the suppression of the shuttle effect using titanium carbide MXenes (Ti3C2Tx, Tx = F, O) as the cathode additives. The findings reveal that the shuttle phenomenon is efficiently resolved because the immense chemical bonding of Na2Sn-Ti3C2Tx interfaces competitively surpasses the binding magnitudes of Na2Sn-electrolyte interaction. The analysis of the electronic density of states and charge density further manifests that there is charge donation from the Na-3s orbital of Na2Sn to the unfilled F(O)-2p orbitals of metallic Ti3C2Tx. The metallicity of the Ti3C2Tx remains preserved during the entire course of the redox process, ensuring the rapid electrochemical kinetics. Furthermore, the presence of Ti3C2Tx additives drastically reduces the dissociation barrier of the final redox product Na2S, yielding the efficient utilization of sulfur during the discharge process. This work has proposed the unexplored functionality of Ti3C2Tx as the anchoring materials for RT-NSBs.

A flexible, ceramic-rich solid electrolyte for room-temperature sodium-sulfur batteries.

A sodium superionic conductor, Na3Zr2Si2PO12 (NZSP) ceramic, is a promising solid electrolyte (SE) and holds the potential to solve the safety and energy density problems of several sodium-based batteries. In particular, in room temperature sodium-sulfur (RT Na/S) batteries, the use of SEs can solve polysulfide shuttle effects. A significant challenge in the commercialization of NZSP is producing the ceramic in a thin and flexible form. Herein, we report a method to produce a thin (<250 μm thickness) and flexible "polymer in ceramic" type sodium ion conductor film from the erstwhile brittle ceramic film and demonstrate its application in RT Na/S batteries.

Progress in the development of solid-state electrolytes for reversible room-temperature sodium–sulfur batteries

Solid electrolytes for room-temperature sodium–sulfur batteries have gained acceptance considering the advantages of safety, mitigating the polysulfide shuttling, stable cycling and mechanical property, which suppresses dendrite proliferation.

Gallate-MOF derived CoS2/C composites as an accelerated catalyst for room-temperature sodium-sulfur batteries.

CoS2/C microprisms with adsorption-catalysis synergistic effects were designed to be sulfur hosts in room-temperature sodium-sulfur batteries. CoS2/C can act as a polysulfide mediator to inhibit the shuttle effect and as a catalyst to accelerate polysulfide redox kinetics, achieving enhanced capabilities of 623 mA h g-1 after 870 cycles at 1 A g-1.

Tessellated N-doped carbon/CoSe2 as trap-catalyst sulfur hosts for room-temperature sodium–sulfur batteries

Well-designed multi-functional tessellated N-doped carbon/CoSe2 composite materials with excellent electrochemical performance in room-temperature Na–S batteries.

An Efficient Strategy toward Multichambered Carbon Nanoboxes with Multiple Spatial Confinement for Advanced Sodium-Sulfur Batteries.

Intricate hollow carbon structures possess vital function for anchoring polysulfides and enhancing the utilization of sulfur in room-temperature sodium-sulfur batteries. However, their synthesis is extremely challenging due to the complex structure. Here, a facile and efficient strategy is developed for the controllable synthesis of N/O-doped multichambered carbon nanoboxes (MCCBs) by selective etching and stepwise carbonization of ZIF-8 nanocubes. The MCCBs consist of porous carbon shells on the outside and connected carbon grids with a hollow structure on the inside, bringing about a MCCBs structure. As a sulfur host, the multichambered structure has better spatial encapsulation and integrated conductivity via the inner interconnected carbon grids, which combines the characteristics of short charge transfer path and superb physicochemical adsorption along with mechanical strength. As expected, the S@MCCBs cathode realizes decent cycle stability (0.045% capacity decay per cycle over 800 cycles at 5 A g-1) and enhanced rate performance (328 mA h g-1 at 10 A g-1). Furthermore, in situ transmission electron microscopy (TEM) observation confirms the good structural stability of the S@MCCBs during the (de)sodiation process. Our work demonstrates an effective strategy for the rational design and accurate construction of intricate hollow materials for high-performance energy storage systems.

Sulfurized Cyclopentadienyl Nanocomposites for Shuttle-Free Room-Temperature Sodium-Sulfur Batteries.

A major challenge hindering the practical adoption of room-temperature sodium-sulfur batteries (NaSBs) is polysulfide dissolution and shuttling, which results in irreversible capacity decay and low Coulombic efficiencies. In this work, we demonstrate for the first time NaSBs using a ferrocene-derived amorphous sulfurized cyclopentadienyl composite (SCC) cathode. Polysulfide dissolution is eliminated via covalent bonding between the insoluble short-chain sulfur species and carbon backbone. Control experiments with a metal-free composite analogue determined that the iron species in the SCC does not have a significant role in polysulfide anchoring. Instead, the superior electrochemical performance is attributed to sulfur covalently bonded to carbon and the uniform nanoparticulate morphology of the SCC composite. In the carbonate-based electrolyte, a discharge capacity of 795 mAh g(S)-1 was achieved during early cycling at 0.2 C, and high Coulombic efficiencies close to 100% were maintained with capacity retention of 532 and 442 mAh g(S)-1 after 100 and 200 cycles, respectively.

Potassium hydroxide activated carbon derived from albumen as an efficient sulfur host for room temperature sodium-sulfur batteries

The room temperature sodium–sulfur (RT/NaS) battery provides a potential energy storage technology with high theoretical capacity and low cost. However, the gap between its practical performance and theoretical expectation confines its comprehensive implementation. In this work, a simple annealing process successfully synthesized a hierarchical micro/mesoporous egg carbon with KOH activation (ECK) from albumen as sulfur hosting for RT/NaS batteries. KOH activation plays a vital role in enhancing conductivity, surface area, and porosity. Elemental sulfur was loaded to the ECK through simple heat evaporation to form an ECK@S composite. Even at the high rate of 1 C, the discharge capacity of the ECK@S electrode reached 473 mAh/g and maintained 202 mAh/g after 800 cycles, representing an outstanding performance. Therefore, preparing micro/mesoporous egg carbon by KOH activation creates a promising electrode material for RT/NaS batteries.

Stable sodium-sulfur electrochemistry enabled by phosphorus-based complexation

A series of sodium phosphorothioate complexes are shown to have electrochemical properties attractive for sodium-sulfur battery applications across a wide operating temperature range. As cathode materials, they resolve a long-standing issue of cyclic liquid-solid phase transition that causes sluggish reaction kinetics and poor cycling stability in conventional, room-temperature sodium-sulfur batteries. The cathode chemistry yields 80% cyclic retention after 400 cycles at room temperature and a superior low-temperature performance down to -60 °C. Coupled experimental characterization and density functional theory calculations revealed the complex structures and electrochemical reaction mechanisms. The desirable electrochemical properties are attributed to the ability of the complexes to prevent the formation of solid precipitates over a fairly wide range of voltage.

Biomass Based Porous Carbons As Cathode's Component for Room Temperature Sodium Sulfur Battery

Porous carbons originated from microalgae powder, were synthesized using a hydrothermal carbonization followed by the chemical-activation process. Porous carbons are the used as cathode's components with sulfur for Sodium Sulfur (NaS) Batteries. the presence of the carbons in the composites can increase the electrical conductivity and assist the sodium ion transfer in the cell since it can allow the electrolyte to permeate easily. The micropores (<2 nm) of porous carbons are the main sulfur host and help to adsorb the small sulfur molecules , so it can improve the electrochemical performance of carbon-sulfur composites as cathodes for NaS batteries at room temperature. The porous carbons can form more actives site that improves the electrical conductivity and prevent the shuttle effect of polysulfide The composite cathodes can give a high initial discharge capacity of 1267 mAh g−1 at 0.1 C and a superior capacity retention of 267 mAh g−1 after 100 cycles at 1 C. This study suggest that microalgae can be used in the application of the room temperature NaS battery.

Regulating the Deposition of Insoluble Sulfur Species for Room Temperature Sodium-Sulfur Batteries

Regulating the Deposition of Insoluble Sulfur Species for Room Temperature Sodium-Sulfur Batteries

A sodium bis(perfluoropinacol) borate-based electrolyte for stable, high-performance room temperature sodium-sulfur batteries based on sulfurized poly(acrylonitrile)

Sodium bis(perfluoropinacol)borate, NaB[O2C2(CF3)4]2 (Na-PPB), as part of the electrolyte is introduced to room temperature (RT) sodium-sulfur batteries based on a sulfurized poly(acrylonitrile) (Na-SPAN) cathode. Na-PPB was stable under atmospheric conditions for 20 days and showed no sign of degradation. Na-SPAN full cells based on a Na-PPB electrolyte demonstrated excellent oxidation stability against various current collectors and delivers a high discharge capacity of >950 mAh/gsulfur with 100 % coulombic efficiency over 500 cycles.

Ni@Ni3N Embedded on Three-Dimensional Carbon Nanosheets for High-Performance Lithium/Sodium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are recognized as one of the most promising next-generation energy storage devices, but their practical application is greatly limited by several obstacles, such as the highly insulating nature and sluggish redox kinetics of sulfur and the dissolution of lithium polysulfides. Herein, three-dimensional carbon nanosheet frameworks anchored with Ni@Ni3N heterostructure nanoparticles (denoted Ni@Ni3N/CNS) are designed and fabricated by a chemical blowing and thermal nitridation strategy. It is demonstrated that the Ni@Ni3N heterostructure can effectively accelerate polysulfide conversion and promote the chemical trapping of polysulfides. Meanwhile, the carbon nanosheet frameworks of Ni@Ni3N/CNS establish a highly conductive network for fast electron transportation. The cells with Ni@Ni3N heterostructures as the catalyst in the cathode show excellent electrochemical performance, revealing stable cycling over 600 cycles with a low-capacity fading rate of 0.04% per cycle at 0.5 C and high-rate capability (594 mAh g-1 at 3 C). Furthermore, Ni@Ni3N/CNS can also work well in room-temperature sodium-sulfur (RT-Na/S) batteries, delivering a high specific capacity (454 mAh g-1 after 400 cycles at 0.5 C). This work provides a rational way to prepare the metal-metal nitride heterostructures to enhance the performance both of Li-S and RT-Na/S batteries.

Recent Advances of Catalytic Effects in Cathode Materials for Room-Temperature Sodium-Sulfur Batteries.

Electrocatalysts in room-temperature sodium-sulfur (RT-Na/S) have captured numerous attention. But, they suffered from shuttle effect and surface passivation. RT-Na/S show inferior energy-storage abilities, ascribed to the larger radii of Na-ions. Herein, the vigorous review is displayed from different kinds of metal-based traits, containing single metal, metal-based samples, and multifunctional hybrids. Through the controlling of structures and composition, the conversion reaction about liquid/solid phases would be enhanced, accompanied by the enhancements of cycling stabilities and rate properties, which enables the break-through of practical applications. The in-depth influences of catalytic effects on the Na-S reaction mechanism and the corresponding electrochemical performance in recently representative works are systematically reviewed. Particularly, this review is anticipated to propose potential research directions for further enhancement of RT-Na/S batteries.