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With the development of energy storage technology, the new energy storage materials are more diverse. The sodium metal has the advantages of high energy density, rich resource reserves, and low costs for raw materials, becoming promising advanced energy storage materials for application. However, the low tensile strength of sodium metal makes it difficult to process deformation while its severe viscosity and low melting point affect the subsequent manufactory and application of batteries. These characteristics hinder the processing and preparation of thin‐sodium metal. The designs of composite‐supporting structure, alloying, and the interface strengthening for sodium metal can effectively overcome the difficulties in preparation of the thin sodium. In this review, the design principles of thin sodium in terms of processing and preparation, according to the physical and chemical properties of sodium metal, are discussed. Meanwhile, the key challenges and new development opportunities are addressed for the processing and preparation of the thin‐sodium metal, which is beneficial for deeply understanding the reliable fabrication and realizing the practical application of thin‐sodium metals. This review provides three design strategies systematically (Support structure composite, interface design and alloying) for the preparation of thin sodium metal based on the characteristics of sodium metal. The electrochemical application characteristics of each design are also explained. In addition, it provides an overview of the challenges on large‐scale processing thin sodium metal.

Sodium metal batteries are arousing extensive interest owing to their high energy density, low cost and wide resource. However, the practical development of sodium metal batteries is inherently plagued by the severe volume expansion and the dendrite growth of sodium metal anode during long cycles under high current density. Herein, a simple electrospinning method is applied to construct the uniformly nitrogen-doped porous carbon fiber skeleton and used as three-dimensional (3D) current collector for sodium metal anode, which has high specific surface area (1,098 m 2 /g) and strong binding to sodium metal. As a result, nitrogen-doped carbon fiber current collector shows a low sodium deposition overpotential and a highly stable cyclability for 3,500 h with a high coulombic effciency of 99.9% at 2 mA/cm 2 and 2 mAh/cm 2 . Moreover, the full cells using carbon coated sodium vanadium phosphate as cathode and sodium pre-plated nitrogen-doped carbon fiber skeleton as hybrid anode can stably cycle for 300 times. These results illustrate an effective strategy to construct a 3D uniformly nitrogen-doped carbon skeleton based sodium metal hybrid anode without the formation of dendrites, which provide a prospect for further development and research of high performance sodium metal batteries.

Herein, hierarchically structured microgrid frameworks of Co3O4 and carbon composite deposited on reduced graphene oxide (Co3O4@C/rGO) are demonstrated through the three‐dimensioinal (3D) printing method, where the porous structure is controllable and the height and width are scalable, for dendrite‐free Na metal deposition. The sodiophilicity, facile Na metal deposition kinetics, and NaF‐rich solid electrolyte interphase (SEI) formation of cubic Co3O4 phase are confirmed by combined spectroscopic and computational analyses. Moreover, the uniform and reversible Na plating/stripping process on 3D‐printed Co3O4@C/rGO host is monitored in real time using in situ transmission electron and optical microscopies. In symmetric cells, the 3D printed Co3O4@C/rGO electrode achieves a long‐term stability over 3950 at 1 mA cm−2 and 1 mAh cm−2 with a superior Coulombic efficiency (CE) of 99.87% as well as 120 h even at 20 mA cm−2 and 20 mAh cm−2, far exceeding the previously reported carbon‐based hosts for Na metal anodes. Consequently, the full cells of 3D‐printed Na@Co3O4@C/rGO anode with 3D‐printed Na3V2(PO4)3@C‐rGO cathode (≈15.7 mg cm−2) deliver the high specific capacity of 97.97 mAh g−1 after 500 cycles with a high CE of 99.89% at 0.5 C, demonstrating the real operation of flexible Na metal batteries. A 3D‐printed sodiophilic Co3O4@C/rGO microlattice aerogel is designed as the host of Na metal anodes, which achieve an ultra‐large areal capacity of 20 mAh cm−2 at 20 mA cm−2. In situ TEM and in situ microscopy observations showcase a dendrite‐free Na metal deposition upon the 3D‐printed Co3O4@C/rGO host, as further evidenced by SEM, XPS, and AIMD analyses.

Sodium metal is a promising anode for sodium batteries due to its high theoretical capacity and low cost. However, the serious Na dendrite growth and low Coulombic efficiency, especially at high current densities/cycling capacities, severely limit the application of sodium metal anodes. Herein, trifluoromethylfullerene, C 60 (CF 3 ) 6 , is designed as an electrolyte additive to enable the high-rate cycling of sodium metal anodes with high Coulombic efficiency. The CF 3 groups contribute to the formation of stable NaF-rich solid electrolyte interface layer, while C 60 cages induce the uniform distribution of sodium ions and promote the formation of smooth and compact morphology. Thus, Na∥Cu cell with C 60 (CF 3 ) 6 can be cycled at 2 mA·cm −2 and 10 mAh·cm −2 over 180 cycles with an average Coulombic efficiency of 99.9%, and Na∥Na cell can be cycled at 10 mA·cm −2 over 600 cycles. Furthermore, Na∥NaV 2 (PO 4 ) 3 @C full cell exhibits high capacity retention of 84% over 2,000 cycles at 20 C (∼ 3 mA·cm −2 ).

Rechargeable room-temperature sodium–sulfur (Na–S) and sodium–selenium (Na–Se) batteries are gaining extensive attention for potential large-scale energy storage applications owing to their low cost and high theoretical energy density. Optimization of electrode materials and investigation of mechanisms are essential to achieve high energy density and long-term cycling stability of Na–S(Se) batteries. Herein, we provide a comprehensive review of the recent progress in Na–S(Se) batteries. We elucidate the Na storage mechanisms and improvement strategies for battery performance. In particular, we discuss the advances in the development of battery components, including high-performance sulfur cathodes, optimized electrolytes, advanced Na metal anodes and modified separators. Combined with current research achievements, this review outlines remaining challenges and clear research directions for the future development of practical high-performance Na–S(Se) batteries. Graphic Abstract

An efficient method for the synthesis of a self‐supporting carbon framework (denoted Gra‐GC‐MoSe2) is proposed with a triple‐gradient structure—in sodiophilic sites, pore volume, and electrical conductivity—which facilitates the highly efficient regulation of Na deposition. In situ and ex situ measurements, together with theoretical calculations, reveal that the gradient distribution of Se heteroatoms in MoSe2, and its derivatives tailor the sodiophilicity, while the gradient distribution of porous nanostructures homogenizes the Na+ diffusion. Therefore, Na deposition occurs from the bottom to the top of the Gra‐GC‐MoSe2 framework without dendrite formation. In addition, the gradient in electrical conductivity ensures the stripping process does not lead to dead Na. As a result, a Gra‐GC‐MoSe2 modified Na anode (Na@Gra‐GC‐MoSe2) shows impressive cycling stability with a high average Coulombic efficiency in an asymmetric cell. In symmetric cells, it also exhibits a long cycling life of 2000 h with a low polarization voltage and works stably even under a large capacity of 10 mAh cm−2. Moreover, a Na@Gra‐GC‐MoSe2|| Na3V2(PO4)3 full cell delivers a high energy density with an excellent cycling performance. A self‐supporting carbon framework with triple gradients is prepared for high‐performance Na metal anodes without dendrite problems. The tailored gradients of the number of sodiophilic sites, pore volumes, and electrical conductivity homogenize Na+ and electron diffusion, thus inducing Na to preferentially deposit on the side furthest away from the separator and enhancing the reversibility of the plating/stripping process.

Sodium metal is one of the ideal anodes for high-performance rechargeable batteries because of its high specific capacity (~ 1166 mAh·g −1 ), low reduction potential (−2.71 V compared to standard hydrogen electrodes), and low cost. However, the unstable solid electrolyte interphase, uncontrolled dendrite growth, and inevitable volume expansion hinder the practical application of sodium metal anodes. At present, many strategies have been developed to achieve stable sodium metal anodes. Here, we systematically summarize the latest strategies adopted in interface engineering, current collector design, and the emerging methods to improve the reaction kinetics of sodium deposition processes. First, the strategies of constructing protective layers are reviewed, including inorganic, organic, and mixed protective layers through electrolyte additives or pretreatments. Then, the classification of metal-based, carbon-based, and composite porous frames is discussed, including their function in reducing local deposition current density and the effect of introducing sodiophilic sites. Third, the recent progress of alloys, nanoparticles, and single atoms in improving Na deposition kinetics is systematically reviewed. Finally, the future research direction and the prospect of high-performance sodium metal batteries are proposed.

Sodium metal anode holds great potential for high energy density sodium batteries. However, its practical utilization is impeded by significant volume change and uncontrolled dendrite growth. To tackle these issues, a three‐dimensional (3D) hierarchical porous sodiophilic reduced graphene oxide/diamane (rGO/diamane) microlattice aerogel is constructed by a direct ink writing (DIW) 3D printing (3DP) method. The molten Na is diffused into the rGO/diamane host to form Na@rGO/diamane anode, which can deliver an ultra‐high capacity of 78.60 mAh cm−2 (1090.94 mAh g−1). Benefiting from uniform ion distribution and homogeneously distributed sodiophilic diamane enabled dendrite‐free deposition morphology, the Na@rGO/diamane anodes exhibit a long cycle‐life of over 7200 h at 1 mA cm−2 with 1 mAh cm−2. Furthermore, the Na@rGO/diamane anode also enhances the long‐term stability at an elevated operation temperature of 60 °C, sustaining a prolonged lifespan of 400 h at 1 mA cm−2 with 1 mAh cm−2. Notably, when integrated with the Na3V2(PO4)3@carbon (NVP@C) cathode and Na@rGO/diamane anode, the full cell delivers sustained longevity, maintaining a lifespan of over 2000 cycles with a capacity retention rate of 95.72%. This work sheds new insights into the application of diamane for the development of stable and high‐performance sodium metal batteries. A 3D printed sodiophilic rGO/diamane microlattice aerogel with uniform ions flux and exceptional sodiophilic features is demonstrated as a stable host for sodium metal anode. The sodiophilic diamane nanoflakes regulate the uniform deposition of metallic Na with a dendrite‐free deposition morphology, achieving an ultra‐high areal capacity of 78.60 mAh cm−2 and a cycle lifespan of 7200 h.

Abundant and inexpensive sodium metal anode with low redox potential and high theoretical capacity shows great potential in next-generation high-energy–density energy storage batteries. However, the uncontrollable growth of sodium dendrites during cycling decays cell cycle life, limiting the practical application and large-scale production of sodium metal batteries. To resolve this problem, researchers have proposed many strategies to inhibit the growth of sodium dendrites. Among those strategies, metal current collectors structuring stands out for its unique role in mitigating volume fluctuations caused by sodium metal plating/stripping, reducing energy barrier for sodium nucleation, and providing a large number of nucleation sites. Therefore, this review presents the basic requirements for metallic current collectors of sodium metal anodes and summarizes research progress of three common categories of metallic current collectors. Finally, the challenges and future directions of further modifying metallic current collectors are proposed.

Sodium metal anodes combine low redox potential (−2.71 V versus SHE) and high theoretical capacity (1165 mAh g−1), becoming a promising anode material for sodium‐ion batteries. Due to the infinite volume change, unstable SEI films, and Na dendrite growth, it is arduous to achieve a long lifespan. Herein, an oxygen‐doped carbon foam (OCF) derived from starch is reported. Heteroatom doping can significantly reduce the nucleation resistance of sodium metal; combined with its rich pore structure and large specific surface area, OCF provides abundant nucleation sites to effectively guide the nucleation and subsequent growth of sodium metal, and the nature of this foam can accommodate the deposited sodium. Furthermore, a more uniform, robust, and stable SEI layer is observed on the surface of OCF electrode, so it can maintain ultra‐high reversibility and excellent integrity for a long time without dendritic growth. As a result, when the current density is 10 mA cm−2, the electrode can maintain stable 2000 cycles and the coulombic efficiency can reach to 99.83%. Na@OCF||Na3V2(PO4)3 full cell also has extremely high capacity retention of about 97.53% over 150 cycles. These results provide a simple but effective method for achieving the safety and commercialization of sodium metal anode. An O‐doped carbon foam with a sodiophilic surface is constructed and applied to the sodium metal anode. The excellent sodiophilic property, abundant porous structure, and large specific surface make the material stable during multiple plating/stripping processes, and no sodium dendrites are formed. Consequently, the sodium metal battery exhibits excellent electrochemical performance.