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Sodium-oxygen batteries have been regarded as promising energy storage devices due to their low overpotential and high energy density. Its applications, however, still face formidable challenges due to the lack of understanding about the influence of electrocatalysts on the discharge products. Here, a phosphorous and nitrogen dual-doped carbon (PNDC) based cathode is synthesized to increase the electrocatalytic activity and to stabilize the NaO2 superoxide nanoparticle discharge products, leading to enhanced cycling stability when compared to the nitrogen-doped carbon (NDC). The PNDC air cathode exhibits a low overpotential (0.36 V) and long cycling stability (120 cycles). The reversible formation/decomposition and stabilization of the NaO2 discharge products are clearly proven by in-situ synchrotron X-ray diffraction and ex-situ X-ray diffraction. Based on the density functional theory calculation, the PNDC has much stronger adsorption energy (-2.85 eV) for NaO2 than that of NDC (-1.80 eV), which could efficiently stabilize the NaO2 discharge products., (© 2024 Wiley‐VCH GmbH.)

Intrinsically safe sodium-ion batteries are considered as a promising candidate for large-scale energy storage systems. However, the high flammability of conventional electrolytes may pose serious safety threats and even explosions. Herein, a strategy of constructing a deep eutectic electrolyte is proposed to boost the safety and electrochemical performance of succinonitrile (SN)-based electrolyte. The strong hydrogen bond between S═O of 1,3,2-dioxathiolane-2,2-dioxide (DTD) and the α-H of SN endows the enhanced safety and compatibility of SN with Lewis bases. Meanwhile, the DTD participates in the inner Na + sheath and weakens the coordination number of SN. The unique solvation configuration promotes the formation of robust gradient inorganic-rich electrode-electrolyte interphase, and merits stable cycling of half-cells in a wide temperature range, with a capacity retention of 82.8% after 800 cycles (25 °C) and 86.3% after 100 cycles (60 °C). Correspondingly, the full cells deliver tremendous improvement in cycling stability and rate performance., (© 2024 Wiley‐VCH GmbH.)

Potassium-ion batteries (PIBs) are considered potential candidates for large-scale energy storage systems due to the abundant resources of potassium. Among various reported anode materials, bismuth anodes with the advantages of high theoretical specific capacity, low cost, and nontoxicity have attracted widespread attention. However, bismuth anodes experience significant volume changes during the charge/discharge process, leading to unsatisfactory cycling stability and rate performance. In this review, we focus on summarizing the research progress of bismuth anodes in PIBs. We discuss in detail the modification strategies for bismuth anodes in PIBs, including electrolyte optimization, morphology design, and hybridization with carbon materials. In addition, we attempt to propose possible future directions for the development of bismuth anodes in PIBs, aiming to expedite their practical application. It is believed that this review can assist researchers in more efficiently designing high-performance bismuth anode materials for PIBs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Cobalt substitution for manganese sites in Na 0.44 MnO 2 initiates a dynamic structural evolution process, yielding a composite cathode material comprising intergrown P2 and P3 phases. The novel P2/P3 composite cathode exhibits a reversible phase transition process during Na + extraction/insertion, showcasing its attractive battery performance in sodium-ion batteries.

High-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) is one of the most promising cathode candidates for rechargeable lithium-ion batteries (LIBs) but suffers from deteriorated cycling stability due to severe interfacial side reactions and manganese dissolution. Herein, a micro-nano porous spherical LNMO cathode was designed for high-performance LIBs. The disordered structure and the preferred exposure of the {111} facets can be controlled by the release of lattice oxygen in the high-temperature calcination process. The unique configuration of this material could enhance the structural stability and play a crucial role in inhibiting manganese dissolution, promoting the rapid transport of Li + , and reducing the volume strain during the charge/discharge process. The designed cathode exhibits a remarkable discharge capacity of 136.7 mA h g -1 at 0.5C, corresponding to an energy density of up to 636.4 W h kg -1 , unprecedented cycling stability (capacity retention of 90.6% after 500 cycles) and superior rate capability (78.9% of initial capacity at 10C). The structurally controllable preparation strategy demonstrated in this work provides new insights into the structural design of cathode materials for LIBs., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Zn deposition with a surface-preferred (002) crystal plane has attracted extensive attention due to its inhibited dendrite growth and side reactions. However, the nucleation and growth of the Zn(002) crystal plane are closely related to the interfacial properties. Herein, oriented growth of Zn(002) crystal plane is realized on Ag-modified surface that is directly visualized by in situ atomic force microscopy. A solid solution HCP-Zn (~1.10 at. % solubility of Ag, 30 °C) is formed on the Ag coated Zn foil (Zn@Ag) and possesses the same crystal structure as Zn to reduce its nucleation barrier caused by their lattice mismatch. It merits oriented Zn deposition and corrosion-resistant surface, and presents long cycling stability in symmetric cells and full cells coupled with V 2 O 5 cathode. This work provides insights into interfacial regulation of Zn anodes for high-performance aqueous zinc metal batteries., (© 2024 Wiley-VCH GmbH.)

P3-layered transition oxide cathodes have garnered considerable attention owing to their high initial capacity, rapid Na + kinetics, and less energy consumption during the synthesis process. Despite these merits, their practical application is hindered by the substantial capacity degradation resulting from unfavorable structural transformations, Mn dissolution and migration. In this study, we systematically investigated the failure mechanisms of P3 cathodes, encompassing Mn dissolution, migration, and the irreversible P3-O3' phase transition, culminating in severe structural collapse. To address these challenges, we proposed an interfacial spinel local interlocking strategy utilizing P3/spinel intergrowth oxide as a proof-of-concept material. As a result, P3/spinel intergrowth oxide cathodes demonstrated enhanced cycling performance. The effectiveness of suppressing Mn migration and maintaining local structure of interfacial spinel local interlocking strategy was validated through depth-etching X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and in situ synchrotron-based X-ray diffraction. This interfacial spinel local interlocking engineering strategy presents a promising avenue for the development of advanced cathode materials for sodium-ion batteries.

Sodium-ion batteries (SIBs) are experiencing a large-scale renaissance to supplement or replace expensive lithium-ion batteries (LIBs) and low energy density lead-acid batteries in electrical energy storage systems and other applications. In this case, layered oxide materials have become one of the most popular cathode candidates for SIBs because of their low cost and comparatively facile synthesis method. However, the intrinsic shortcomings of layered oxide cathodes, which severely limit their commercialization process, urgently need to be addressed. In this review, inherent challenges associated with layered oxide cathodes for SIBs, such as their irreversible multiphase transition, poor air stability, and low energy density, are systematically summarized and discussed, together with strategies to overcome these dilemmas through bulk phase modulation, surface/interface modification, functional structure manipulation, and cationic and anionic redox optimization. Emphasis is placed on investigating variations in the chemical composition and structural configuration of layered oxide cathodes and how they affect the electrochemical behavior of the cathodes to illustrate how these issues can be addressed. The summary of failure mechanisms and corresponding modification strategies of layered oxide cathodes presented herein provides a valuable reference for scientific and practical issues related to the development of SIBs.

Hard carbon (HC) is one of the most promising anode materials for sodium-ion batteries (SIBs) due to its cost-effectiveness and low-voltage plateau capacity. Heteroatom doping is considered as an effective strategy to improve the sodium storage capacity of HC. However, most of the previous heteroatom doping strategies are performed at a relatively low temperature, which could not be utilized to raise the low-voltage plateau capacity. Moreover, extra doping of heteroatoms could create new defects, leading to a low initial coulombic efficiency (ICE). Herein, we propose a repair strategy based on doping a trace amount of P to achieve a high capacity along with a high ICE. By employing the cross-linked interaction between glucose and phytic acid to achieve the in situ P doped spherical hard carbon, the obtained PHC-0.2 possesses a large interlayer space that facilitates Na + storage and transportation. In addition, doping a suitable amount of P could repair some defects in carbon layers. When used as an anode material for SIBs, the PHC-0.2 exhibits an enhanced reversible capacity of 343 mA h g -1 at 20 mA g -1 with a high ICE of 92%. Full cells consisting of a PHC-0.2 anode and a Na 2 Fe 0.5 Mn 0.5 [Fe(CN) 6 ] cathode exhibited an average potential of 3.1 V with an initial discharge capacity of 255 mA h g -1 and an ICE of 85%. The full cell displays excellent cycling stability with a capacity retention of 80.3% after 170 cycles. This method is simple and low-cost, which can be extended to other energy storage materials., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Layered oxides have become the research focus of cathode materials for sodium-ion batteries (SIBs) due to the low cost, simple synthesis process, and high specific capacity. However, the poor air stability, unstable phase structure under high voltage, and slow anionic redox kinetics hinder their commercial application. In recent years, the concept of manipulating orbital hybridization has been proposed to simultaneously regulate the microelectronic structure and modify the surface chemistry environment intrinsically. In this review, the hybridization modes between atoms in 3d/4d transition metal (TM) orbitals and O 2p orbitals near the region of the Fermi energy level (E F ) are summarized based on orbital hybridization theory and first-principles calculations as well as various sophisticated characterizations. Furthermore, the underlying mechanisms are explored from macro-scale to micro-scale, including enhancing air stability, modulating high working voltage, and stabilizing anionic redox chemistry. Meanwhile, the origin, formation conditions, and different types of orbital hybridization, as well as its application in layered oxide cathodes are presented, which provide insights into the design and preparation of cathode materials. Ultimately, the main challenges in the development of orbital hybridization and its potential for the production application are also discussed, pointing out the route for high-performance practical sodium layered oxide cathodes., (© 2024 Wiley‐VCH GmbH.)

Alloying-type antimony (Sb) with high theoretical capacity is a promising anode candidate for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Given the larger radius of Na + (1.02 Å) than Li + (0.76 Å), it was generally believed that the Sb anode would experience even worse capacity degradation in SIBs due to more substantial volumetric variations during cycling when compared to LIBs. However, the Sb anode in SIBs unexpectedly exhibited both better electrochemical and structural stability than in LIBs, and the mechanistic reasons that underlie this performance discrepancy remain undiscovered. Here, using substantial in situ transmission electron microscopy, X-ray diffraction, and Raman techniques complemented by theoretical simulations, we explicitly reveal that compared to the lithiation/delithiation process, sodiation/desodiation process of Sb anode displays a previously unexplored two-stage alloying/dealloying mechanism with polycrystalline and amorphous phases as the intermediates featuring improved resilience to mechanical damage, contributing to superior cycling stability in SIBs. Additionally, the better mechanical properties and weaker atomic interaction of Na-Sb alloys than Li-Sb alloys favor enabling mitigated mechanical stress, accounting for enhanced structural stability as unveiled by theoretical simulations. Our finding delineates the mechanistic origins of enhanced cycling stability of Sb anode in SIBs with potential implications for other large-volume-change electrode materials., (© 2024 Wiley-VCH GmbH.)

Non-aqueous solvents, in particular N,N-dimethylaniline (NMP), are widely applied for electrode fabrication since most sodium layered oxide cathode materials are readily damaged by water molecules. However, the expensive price and poisonousness of NMP unquestionably increase the cost of preparation and post-processing. Therefore, developing an intrinsically stable cathode material that can implement the water-soluble binder to fabricate an electrode is urgent. Herein, a stable nanosheet-like Mn-based cathode material is synthesized as a prototype to verify its practical applicability in sodium-ion batteries (SIBs). The as-prepared material displays excellent electrochemical performance and remarkable water stability, and it still maintains a satisfactory performance of 79.6% capacity retention after 500 cycles even after water treatment. The in situ X-ray diffraction (XRD) demonstrates that the synthesized material shows an absolute solid-solution reaction mechanism and near-zero-strain. Moreover, the electrochemical performance of the electrode fabricated with a water-soluble binder shows excellent long-cycling stability (67.9% capacity retention after 500 cycles). This work may offer new insights into the rational design of marvelous water stability cathode materials for practical SIBs., (© 2023 Wiley-VCH GmbH.)

Large reserves, high capacity, and low cost are the core competitiveness of disordered carbon materials as excellent anode materials for sodium-ion batteries (SIBs). And the existence and improper treatment of a large number of organic solid wastes will aggravate the burden on the environment, therefore, it is significant to transform wastes into carbon-based materials for sustainable energy utilization. Herein, a kind of hard carbon materials are reported with waste biomass-foam as the precursor, which can improve the sodium storage performance through pre-oxidation strategy. The introduction of oxygen-containing groups can promote structural cross-linking, and inhibit the melting and rearrangement of carbon structure during high-temperature carbonization that produces a disordered structure with a suitable degree of graphitization. Moreover, the micropore structure are also regulated during the high-temperature carbonization process, which is conducive to the storage of sodium ions in the low-voltage plateau region. The optimized sample as an electrode material exhibits excellent reversible specific capacity (308.0 mAh g -1 ) and initial Coulombic efficiency (ICE, 90.1%). In addition, a full cell with the waste foam-derived hard carbon anode and a Na 3 V 2 (PO 4 ) 3 cathode is constructed with high ICE and energy density. This work provides an effective strategy to conversion the waste to high-value hard carbon anode for sodium-ion batteries., (© 2023 Wiley‐VCH GmbH.)

Na 2 Fe 2 (SO 4 ) 3 (NFS), as a promising cathode for sodium-ion batteries, is still plagued by its poor intrinsic conductivity. In general, hybridization with carbon materials is an effective strategy to improve the sodium storage performance of NFS. However, the role of carbon materials in the electrochemical performance of NFS cathode materials has not been thoroughly investigated. Herein, the effect of carbon materials was revealed by employing various conductive carbon materials as carbon sources. Among these, the NFS coated with Ketjen Black (NFS@KB) shows the largest specific surface area, which is beneficial for electrolyte penetration and rapid ionic/electronic migration, leading to improved electrochemical performance. Therefore, NFS@KB shows a long cycle life (74.6 mA h g -1 after 1000 cycles), superior rate performance (61.5 mA h g -1 at a 5.0 A g -1 ), and good temperature tolerance (-10 °C to 60 °C). Besides, the practicality of the NFS@KB cathode was further demonstrated by assembling a NFS@KB//hard carbon full cell. Therefore, this research indicates that a suitable carbon material for the NFS cathode can greatly activate the sodium storage performance., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

High-performance sodium storage at low temperature is urgent with the increasingly stringent demand for energy storage systems. However, the aggravated capacity loss is induced by the sluggish interfacial kinetics, which originates from the interfacial Na + desolvation. Herein, all-fluorinated anions with ultrahigh electron donicity, trifluoroacetate (TFA - ), are introduced into the diglyme (G2)-based electrolyte for the anion-reinforced solvates in a wide temperature range. The unique solvation structure with TFA - anions and decreased G2 molecules occupying the inner sheath accelerates desolvation of Na + to exhibit decreased desolvation energy from 4.16 to 3.49 kJ mol -1 and 24.74 to 16.55 kJ mol -1 beyond and below -20 °C, respectively, compared with that in 1.0 M NaPF 6 -G2. These enable the cell of Na||Na 3 V 2 (PO 4 ) 3 to deliver 60.2% of its room-temperature capacity and high capacity retention of 99.2% after 100 cycles at -40 °C. This work highlights regulation of solvation chemistry for highly stable sodium-ion batteries at low temperature., Competing Interests: Competing interests statement:The authors declare no competing interest.

Sodium metal batteries have attracted increasing interest recently, but suffer from severe dendrite growth caused by uneven Na plating/stripping behavior, which may result in the piercing of the membrane, with short circuiting and even cause explosions. Herein, a conductive and sodiophilic Ag coating layer is introduced to regulate Na deposition behaviors for highly reversible sodium metal batteries. Ag coated Zn foil with enhanced sodiophilicity, rapid Na + transfer kinetics and superior electronic conductivity guarantee the homogenized Na + ion and electric field distribution. This enables remarkably low overpotentials and uniform Na plating/stripping behavior with ultrahigh Coulombic efficiency of 99.9% during 500 cycles. As expected, the enhanced electrochemical performance of the anode-less battery and anode-free battery coupled with Prussian blue is achieved with the help of Ag coating. This work emphasizes the role of the conductive and sodiophilic coating layer in regulating the Na deposition behaviors for highly reversible sodium metal batteries., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Sodium dual-ion batteries (Na-DIBs) have attracted increasing attention due to their high operative voltages and low-cost raw materials. However, the practical applications of Na-DIBs are still hindered by the issues, such as low capacity and poor Coulombic efficiency, which is highly correlated with the compatibility between electrode and electrolyte but rarely investigated. Herein, fluoroethylene carbonate (FEC) is introduced into the electrolyte to regulate cation/anion solvation structure and the stability of cathode/anode-electrolyte interphase of Na-DIBs. The FEC modulates the environment of PF 6 - solvation sheath and facilitates the interaction of PF 6 - on graphite. In addition, the NaF-rich interphase caused by the preferential decomposition of FEC effectively inhibits side reactions and pulverization of anodes with the electrolyte. Consequently, Sb||graphite full cells in FEC-containing electrolyte achieve an improved capacity, cycling stability and Coulombic efficiency. This work elucidates the underlying mechanism of bifunctional FEC and provides an alternative strategy of building high-performance dual ion batteries., (© 2023 Wiley-VCH GmbH.)

In alkaline seawater electrolysis, the oxygen evolution reaction (OER) is greatly suppressed by the occurrence of electrode corrosion due to the formation of hypochlorite. Herein, a catalyst consisting of MoC nanowires modified with NiFe alloy nanoparticles (NiFe/MoC) on nickel foam (NF) is prepared. The optimized catalyst can deliver a large current density of 500 mA cm -2 at a very low overpotential of 366 mV in alkaline seawater, respectively, outperforming commercial IrO 2 . Remarkably, an electrolyzer assembled with NiFe/MoC/NF as the anode and NiMoN/NF as the cathode only requires 1.77 V to drive a current density of 500 mA cm -2 for alkaline seawater electrolysis, as well as excellent stability. Theory calculation indicates that the initial activity of NiFe/MoC is attributed to increased electrical conductivity and decreased energy barrier for OER due to the introduction of Fe. We find that the change of the catalyst in the composition occurred after the stability test; however, the reconstructed catalyst has an energy barrier close to that of the pristine one, which is responsible for its excellent long-term stability. Our findings provide an efficient way to construct high-performance OER catalysts for alkaline seawater splitting., (© 2023 Wiley-VCH GmbH.)

Hard carbon anodes with all-plateau capacities below 0.1 V are prerequisites to achieve high-energy-density sodium-ion storage, which holds promise for future sustainable energy technologies. However, challenges in removing defects and improving the insertion of sodium ions head off the development of hard carbon to achieve this goal. Herein, a highly cross-linked topological graphitized carbon using biomass corn cobs through a two-step rapid thermal-annealing strategy is reported. The topological graphitized carbon constructed with long-range graphene nanoribbons and cavities/tunnels provides a multidirectional insertion of sodium ions whilst eliminating defects to absorb sodium ions at the high voltage region. Evidence from advanced techniques including in situ XRD, in situ Raman, and in situ/ex situ transmission electron microscopy (TEM) indicates that the sodium ions' insertion and Na cluster formation occurred between curved topological graphite layers and in the topological cavity of adjacent graphite band entanglements. The reported topological insertion mechanism enables outstanding battery performance with a single full low-voltage plateau capacity of 290 mAh g -1 , which is almost 97% of the total capacity., (© 2023 Wiley-VCH GmbH.)

High-voltage lithium-ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte-electrode interphase at high voltage. Herein, a robust additive-induced sulfur-rich interphase is constructed by introducing an additive with ultrahigh S-content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li + sheath, but the strong interactions between MMDS and PF 6 - anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur-rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur-rich additive-induced electrolyte-electrode interphase for stable high-voltage LIBs., (© 2023 Wiley-VCH GmbH.)

As a class of promising cathodes in the field of large-scale power storage systems especially for alkali-metal-ion batteries (MIBs), Prussian blue (PB) and its analogues (PBAs) have received wide research attention due to their open framework, high theoretical specific capacity, and simple synthesis method. For large-scale applications, cathode materials with low-cost and long cycle life are preferred. However, only a few of the review papers have concentrated on the detailed analysis of low-cost PBAs, including Fe-based and Mn-based PBAs, which also show excellent electrochemical performance. This review aims to first provide an all-sided understanding of low-cost PBAs in terms of their application and recent progress in MIBs. Then, the major challenges such as inferior electrochemical properties of low-cost PBAs are discussed. Meanwhile, we provide feasible strategies to prepare PBA electrodes with advanced electrochemical performance. Finally, we present some personal perspectives and guidance for future research, aiming to narrow the gap between laboratory investigation and practical application.

Prussian blue analogues (PBAs) have been regarded as promising cathode materials for alkali-ion batteries owing to their high theoretical energy density and low cost. However, the high water and vacancy content of PBAs lower their energy density and bring safety issues, impeding their large-scale application. Herein, a facile "potassium-ions assisted" strategy is proposed to synthesize highly crystallized PBAs. By manipulating the dominant crystal plane and suppressing vacancies, the as-prepared PBAs exhibit increased redox potential resulting in high energy density up to ≈450 Wh kg -1 , which is at the same level of the well-known LiFePO 4 cathodes for lithium-ion batteries. Remarkably, unconventional highly-reversible phase evolution and redox-active pairs were identified by multiple in situ techniques for the first time. The preferred guest-ion storage sites and migration mechanism were systematically analysed through theoretical calculations. We believe these results could inspire the design of safe with high energy density., (© 2023 Wiley-VCH GmbH.)

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with high mortality, and the efficacy of monotherapy for TNBC is still disappointing. Here, we developed a novel combination therapy for TNBC based on a multifunctional nanohollow carbon sphere. This intelligent material contains a superadsorbed silicon dioxide sphere, sufficient loading space, a nanoscale hole on its surface, a robust shell, and an outer bilayer, and it could load both programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) small-molecule immune checkpoints and small-molecule photosensitizers with excellent loading contents, protect these small molecules during the systemic circulation, and achieve accumulation of them in tumor sites after systemic administration followed by the application of laser irradiation, thereby realizing dual attack of photodynamic therapy and immunotherapy on tumors. Importantly, we integrated the fasting-mimicking diet condition that can further enhance the cellular uptake efficiency of nanoparticles in tumor cells and amplify the immune responses, further enhancing the therapeutic effect. Thus, a novel combination therapy "PD-1/PD-L1 immune checkpoint blockade + photodynamic therapy + fasting-mimicking diet"was developed with the aid of our materials, which eventually achieved a marked therapeutic effect in 4T1-tumor-bearing mice. The concept can also be applied to the clinical treatment of human TNBC with guiding significance in the future., (Copyright © 2023 Yue Yin et al.)

Carbon nanospheres (CNSs) have attracted great interest in energy conversion and storage technologies due to their excellent chemical and thermal stability, high electrical conductivity and controllable size structure characteristics. In order to further improve the energy storage properties, many efforts have been made to design suitable nanocarbon spherical materials to improve electrochemical performance. In this overview, we summarize the recent research progress on CNSs, mainly focusing on the synthesis methods and their application as high-performance electrode materials in rechargeable batteries. As for the synthesis methods, hard template methods, soft template methods, the extension of the Stöber method, hydrothermal carbonization, aerosol-assisted synthesis are described in detail. In addition, the use of CNSs as electrodes in energy storage devices (mainly concentrated on lithium-ion batteries (LIBs)), sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are also discussed in detail in this article. Finally, some perspectives on the future research and development of CNSs are provided.

Zinc-ion batteries (ZIBs) have received much research attention due to their advantages of safety, non-toxicity, simple manufacture, and element abundance. Nevertheless, serious problems still remain for their anodes, such as dendrite development, corrosion, passivation, and the parasitic hydrogen evolution reaction due to their unique aqueous electrolyte system constituting the main issues that must be addressed, which are blocking the further advancement of anodes for Zn-ion batteries. Herein, we conduct an in-depth analysis of the problems that exist for the zinc anode, summarize the main failure types and mechanisms of the zinc anode, and review the main modification strategies for the anode from the three aspects of the electrolyte, anode surface, and anode host. Furthermore, we also shed light on further modification and optimization strategies for the zinc anode, which provide directions for the future development of anodes for zinc-ion batteries., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

It is still very urgent and challenging to simultaneously develop high-rate and long-cycle oxide cathodes for sodium-ion batteries (SIBs) because of the sluggish kinetics and complex multiphase evolution during cycling. Here, the concept of accurately manipulating structural evolution and formulating high-performance heterostructured biphasic layered oxide cathodes by local chemistry and orbital hybridization modulation is reported. The P2-structure stoichiometric composition of the cathode material shows a layered P2- and O3-type heterostructure that is explicitly evidenced by various macroscale and atomic-scale techniques. Surprisingly, the heterostructured cathode displays excellent rate performance, remarkable cycling stability (capacity retention of 82.16% after 600 cycles at 2 C), and outstanding compatibility with hard carbon anode because of the integrated advantages of intergrowth structure and local environment regulation. Meanwhile, the formation process from precursors during calcination and the highly reversible dynamic structural evolution during the Na + intercalation/deintercalation process are clearly articulated by a series of in situ characterization techniques. Also, the intrinsic structural properties and corresponding electrochemical behavior are further elucidated by the density of states and electron localization function of density functional theory calculations. Overall, this strategy, which finely tunes the local chemistry and orbitals hybridization for high-performance SIBs, will open up a new field for other materials., (© 2022 Wiley-VCH GmbH.)

Prussian blue analogues (PBAs) have attracted extensive attention as cathode materials in sodium-ion batteries (SIBs) due to their low cost, high theoretical capacity, and facile synthesis process. However, it is of great challenge to control the crystal vacancies and interstitial water formed during the aqueous co-precipitation method, which are also the key factors in determining the electrochemical performance. Herein, an antioxidant and chelating agent co-assisted non-aqueous ball-milling method to generate highly-crystallized Na 2- x Fe[Fe(CN) 6 ] y with hollow structure is proposed by suppressing the speed and space of crystal growth. The as-prepared Na 2- x Fe[Fe(CN) 6 ] y hollow nanospheres show low vacancies and interstitial water content, leading to a high sodium content. As a result, the Na-rich Na 1.51 Fe[Fe(CN) 6 ] 0.87 ·1.83H 2 O hollow nanospheres exhibit a high initial Coulombic efficiency, excellent cycling stability, and rate performance via a highly reversible two-phase transition reaction confirmed by in situ X-ray diffraction. It delivers a specific capacity of 124.2 mAh g -1 at 17 mA g -1 , presenting ultra-high rate capability (84.1 mAh g -1 at 3400 mA g -1 ) and cycling stability (65.3% capacity retention after 1000 cycles at 170 mA g -1 ). Furthermore, the as-reported non-aqueous ball-milling method could be regarded as a promising method for the scalable production of PBAs as cathode materials for high-performance SIBs., (© 2022 Wiley-VCH GmbH.)

Organic materials have attracted much attention in sodium ion batteries (SIBs) because of their advantages such as being environmentally benign and having high designability. Capacities and cycle life of organic materials are the most important parameters in most research which has been paid much effort to obtain an impressive electrochemical performance on the material level, and the sodium-detachable ability of these materials to directly match with the sodium-free anode is neglected. In this work, one organic sodium salt (C 6 H 2 Na 2 O 6 ) exhibits the unique ability (charging first in half cell) unlike other reported organic cathode materials (normally discharging first) for SIBs. The redox mechanism and structure change are investigated by in situ and ex situ tests to give a better understanding for C 6 H 2 Na 2 O 6 . Satisfying electrochemical performance (74% capacity retention after 600 cycles at 0.05 A g -1 and 63% capacity retention at 5 A g -1 when compared with capacity at 0.05 A g -1 ) is achieved by the C 6 H 2 Na 2 O 6 electrode. In addition, matched with hard carbon, full cells are assembled successfully like other transition metal containing cathode materials because C 6 H 2 Na 2 O 6 electrode can deliver its sodium ions to a sodium-free anode directly without any presodiation., (© 2022 Wiley-VCH GmbH.)

Improving the electrochemical kinetics and the intrinsic poor conductivity of transition metal dichalcogenide (TMD) electrodes is meaningful for developing next-generation energy storage systems. As one of the most promising TMD anode materials, ReS 2 shows attractive performance in potassium-ion batteries (PIBs). To overcome the poor kinetic ion diffusion and limited cycling stability of the ReS 2 -based electrode, herein, the interlayer distance expanding strategy was employed, and reduced graphene oxide (rGO) was introduced into ReS 2 . Few-layered ReS 2 nanosheets were grown on the surface of the rGO with expanded interlayer distance. The prepared ReS 2 nanosheets show an expanded distance (∼0.77 nm). The synthesized EI-ReS 2 @rGO composites were used in PIBs as anode materials. The K-ion storage mechanism of the ReS 2 -based anode was investigated by in situ X-ray diffraction (XRD) technology, which shows the intercalation and conversion types. The EI-ReS 2 @rGO nanocomposites show high specific capacities of 432.5, 316.5, and 241 mAh g -1 under 0.05, 0.2, and 1.0 A g -1 current densities and exhibit excellent reversibility at 1.0 A g -1 . Overall, this strategy, which finely tunes the local chemistry and orbital hybridization for high-performance PIBs, will open up a new field for other materials.

Carbonaceous materials are considered strong candidates as anode materials for sodium-ion batteries (SIBs), which are expected to play an indispensable role in the carbon-neutral era. Herein, novel braided porous carbon fibres (BPCFs) are prepared using the chemical vapour deposition (CVD) method. The BPCFs possess interwoven porous structures and abundant vacancies. The growth mechanism of the BPCFs can be attributed to the polycrystalline transformation of the nanoporous copper catalyst in the early stage of CVD process. Density functional theory calculations suggest that the Na + adsorption energies of the mono-vacancy edges of the BPCFs (-1.22 and -1.09 eV) are lower than that of an ideal graphene layer (-0.68 eV), clarifying in detail the adsorption-dominated sodium storage mechanism. Hence, the BPCFs as an anode material present an outstanding discharge capacity of 401 mAh g -1 at 0.1 A g-1 after 500 cycles. Remarkably, this BPCFs anode, under high-mass-loading of 5 mg cm-2, shows excellent long-term cycling ability with a reversible capacity of 201 mAh g -1 at 10 A g -1 over 1000 cycles. This study provided a novel strategy for the development of high-performance carbonaceous materials for SIBs., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

High energy density and long-term cycling stability are crucial factors for the commercialization of sodium batteries in large scale. In this regard, cathode materials that can operate at high voltage have attracted great interest owing to their high energy density. However, traditional electrolytes cannot be used in high-voltage sodium batteries due to their limited oxidative stability. Therefore, there is a great challenge to develop appropriate electrolytes for high-voltage cathode materials. Herein, a diluted fluoroethylene carbonate (FEC)-based electrolyte (1 m NaPF 6 in FEC/DMC = 2/8 by volume) is designed for Na 4 Co 3 (PO 4 ) 2 P 2 O 7 (NCPP) cathode with a high operation voltage of 4.7 V to achieve superior electrochemical performance with a capacity retention of 90.10% after 500 cycles at 0.5 C and capacity retention of 89.99% after 1000 cycles at 1 C. The excellent electrochemical performance of the NCPP||Na cells can be attributed to the formation of inorganic and robust NaF-rich cathode electrolyte interphase and F-rich solid electrolyte interface on high voltage NCPP cathode and Na metal anode, respectively. This work points out a very promising strategy to develop high-voltage sodium batteries toward practical applications., (© 2022 Wiley-VCH GmbH.)

It is vital to dynamically regulate S activity to achieve efficient and stable room-temperature sodium-sulfur (RT/Na-S) batteries. Herein, we report using cobalt sulfide as an electron reservoir to enhance the activity of sulfur cathodes, and simultaneously combining with cobalt single atoms as double-end binding sites for a stable S conversion process. The rationally constructed CoS 2 electron reservoir enables the straight reduction of S to short-chain sodium polysulfides (Na 2 S 4 ) via a streamlined redox path through electron transfer. Meanwhile, cobalt single atoms synergistically work with the electron reservoir to reinforce the streamlined redox path, which immobilize in situ formed long-chain products and catalyze their conversion, thus realizing high S utilization and sustainable cycling stability. The as-developed sulfur cathodes exhibit a superior rate performance of 443 mAh g -1 at 5 A g -1 with a high cycling capacity retention of 80 % after 5000 cycles at 5 A g -1 ., (© 2022 Wiley-VCH GmbH.)

Electroactive acid anhydride with multicarbonyl is highly promising for electrochemical energy storage because of its high specific capacity and environmental benignity. Its low electrical conductivity and high dissolution in organic electrolyte, however, result in poor cycling and rate capabilities. Here, we report a naphthalene polyimide derivative (NPI) synthesized by using anhydride under condensation polymerization conditions, along with its composite with graphene (NPI-G) fabricated via in situ polymerization. The composite delivers a high reversible capacity and outstanding cycling stability and rate capability as a cathode for sodium-ion batteries (SIBs) owing to the formation of a polymer, the improvement in the electrical conductivity brought about by the highly dispersed graphene sheets, and the enhancement of structural stability resulting from the π-π stacking interaction between the phenyl groups of NPI and the six-member carbon rings of graphene. This investigation sheds light on the development, design, and screening of next-generation organic electrode materials with high performance for SIBs.

The shuttling behavior and sluggish conversion kinetics of the intermediate lithium polysulfides (LiPS) represent the main obstructions to the practical application of lithium-sulfur batteries (LSBs). Herein, a 1D π-d conjugated metal-organic framework (MOF), Ni-MOF-1D, is presented as an efficient sulfur host to overcome these limitations. Experimental results and density functional theory calculations demonstrate that Ni-MOF-1D is characterized by a remarkable binding strength for trapping soluble LiPS species. Ni-MOF-1D also acts as an effective catalyst for S reduction during the discharge process and Li 2 S oxidation during the charging process. In addition, the delocalization of electrons in the π-d system of Ni-MOF-1D provides a superior electrical conductivity to improve electron transfer. Thus, cathodes based on Ni-MOF-1D enable LSBs with excellent performance, for example, impressive cycling stability with over 82% capacity retention over 1000 cycles at 3 C, superior rate performance of 575 mAh g -1 at 8 C, and a high areal capacity of 6.63 mAh cm -2 under raised sulfur loading of 6.7 mg cm -2 . The strategies and advantages here demonstrated can be extended to a broader range of π-d conjugated MOFs materials, which the authors believe have a high potential as sulfur hosts in LSBs., (© 2022 Wiley-VCH GmbH.)

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., (© 2022 Wiley-VCH GmbH.)

Silicon is considered the most promising candidate for anode material in lithium-ion batteries due to the high theoretical capacity. Unfortunately, the vast volume change and low electric conductivity have limited the application of silicon anodes. In the silicon anode system, the binders are essential for mechanical and conductive integrity. However, there are few reviews to comprehensively introduce binders from the perspective of factors affecting performance and modification methods, which are crucial to the development of binders. In this review, several key factors that have great impact on binders' performance are summarized, including molecular weight, interfacial bonding, and molecular structure. Moreover, some commonly used modification methods for binders are also provided to control these influencing factors and obtain the binders with better performance. Finally, to overcome the existing problems and challenges about binders, several possible development directions of binders are suggested., (© 2021 Wiley-VCH GmbH.)

The safety of energy storage equipment has always been a stumbling block to the development of battery, and sodium ion battery is no exception. However, as an ultimate solution, the use of non-flammable electrolyte is susceptible to the side effects, and its poor compatibility with electrode, causing failure of batteries. Here, we report a non-flammable electrolyte design to achieve high-performance sodium ion battery, which resolves the dilemma via regulating the solvation structure of electrolyte by hydrogen bonds and optimizing the electrode-electrolyte interphase. The reported non-flammable electrolyte allows stable charge-discharge cycling of both sodium vanadium phosphate@hard carbon and Prussian blue@hard carbon full pouch cell for more than 120 cycles with a capacity retention of >85 % and high cycling Coulombic efficiency (99.7 %)., (© 2021 Wiley-VCH GmbH.)

Metal-organic frameworks (MOFs) with intrinsically porous structures and well-dispersed metal sites are promising candidates for electrocatalysis; however, the catalytic efficiencies of most MOFs are significantly limited by their impertinent adsorption/desorption energy of intermediates formed during electrocatalysis and very low electrical conductivity. Herein, Co is introduced into conductive Cu-catecholate (Cu-CAT) nanorod arrays directly grown on a flexible carbon cloth for hydrogen evolution reaction (HER). Electrochemical results show that the Co-incorporated Cu-CAT nanorod arrays only need 52 and 143 mV overpotentials to drive a current density of 10 mA cm -2 in alkaline and neutral media for HER, respectively, much lower than most of the reported non-noble metal-based electrocatalysts and comparable to the benchmark Pt/C electrocatalyst. Density functional theory calculations show that the introduction of Co can optimize the adsorption energy of hydrogen (ΔG H* ) of Cu sites, almost close to that of Pt (111). Furthermore, the adsorption energy of water ( Δ E H 2 O ) of Co sites in the CuCo-CAT is significantly lower than that of Cu sites upon coupling Cu with Co, effectively accelerating the Volmer step in the HER process. The findings, synergistic effect of bimetals, open a new avenue for the rational design of highly efficient MOF-based electrocatalysts., (© 2021 Wiley-VCH GmbH.)

Alkali-metal/sulfur batteries hold great promise for offering relatively high energy density compared to conventional lithium-ion batteries. By providing viable sulfur composites that can be effectively used, carbonaceous hosts as a key component play critical roles in overcoming the preliminary challenges associated with the insulating sulfur and its relatively soluble polysulfides. Herein, a comprehensive overview and recent progress on carbonaceous hosts for advanced next-generation alkali-metal/sulfur batteries are presented. In order to encapsulate the highly active sulfur mass and fully limit polysulfide dissolution, strategies for tailoring the design and synthesis of carbonaceous hosts are summarized in this work. The sticking points that remain for sulfur cathodes in current alkali-metal/sulfur systems and the future remedies that can be provided by carbonaceous hosts are also indicated, which can lead to long cycling lifetimes and highly reversible capacities under repeated sulfur reduction reactions in alkali-metal/sulfur during cycling., (© 2021 Wiley-VCH GmbH.)

Binders as a bridge in electrodes can bring various components together thus guaranteeing the integrity of electrodes and electronic contact during battery cycling. In this review, we summarize the recent progress of traditional binders and novel binders in the different electrodes of SIBs. The challenges faced by binders in terms of bond strength, wettability, thermal stability, conductivity, cost, and environment are also discussed in details. Correspondingly, the designing principle and advanced strategies of future research on SIB binders are also provided. Moreover, a general conclusion and perspective on the development of binder design for SIBs in the future are presented.

Alkali and alkaline-earth metal ion-solvent co-intercalation reactions have attracted extensive attention in recent years owing to the advantage of the absence of a desolvation process, which generally results in fast kinetics and good rate performance for batteries. However, less attention has been paid to summarizing the mechanism, performance and other related aspects about ion-solvent co-intercalation reaction in batteries. A summary of alkali and alkaline-earth metal ion-solvent co-intercalation reactions in nonaqueous rechargeable batteries is presented in this review, which mainly focuses on the electrochemical performance, ion-solvent co-intercalation mechanism, conditions for reversible ion-solvent co-intercalation and potential for practical application. It is suggested that future research should focus on reducing the redox potential of the ion-solvent co-intercalation reaction to achieve high energy-density and power-density full cells. This review provides an understanding of alkali and alkaline-earth metal ion-solvent co-intercalation reactions in nonaqueous rechargeable batteries and will serve as significant guidance for researchers to further develop ion-solvent co-intercalation reactions for fast-charging batteries., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Developing hard carbon with a high initial Coulombic efficiency (ICE) and very good cycling stability is of great importance for practical sodium-ion batteries (SIBs). Defects and oxygen-containing groups grown along either the carbon edges or the layers, however, are inevitable in hard carbon and can cause a tremendous density of irreversible Na + sites, decreasing the efficiency and therefore causing failure of the battery. Thus, eliminating these unexpected defect structures is significant for enhancing the battery performance. Herein, we develop a strategy of applying a soft-carbon coating onto free-standing hard-carbon electrodes, which greatly hinders the formation of defects and oxygen-containing groups on hard carbon. The electrochemical results show that the soft-carbon-coated, free-standing hard-carbon electrodes can achieve an ultrahigh ICE of 94.1% and long cycling performance (99% capacity retention after 100 cycles at a current density of 20 mA g -1 ), demonstrating their great potential in practical sodium storage systems. The sodium storage mechanism was also investigated by operando Raman spectroscopy. Our sodium storage mechanism extends the "adsorption-intercalation-pore filling-deposition" model. We propose that the pore filling in the plateau area might be divided into two parts: (1) sodium could fill in the pores near the inner wall of the carbon layer; (2) when the sodium in the inner wall pores is close to saturation, the sodium could be further deposited onto the existing sodium.

Intercalation-based anode materials can be considered as the most promising anode candidates for large-scale sodium-ion batteries (SIBs), owing to their long-term cycling stability and environmental friendliness, as well as their natural abundance. Nevertheless, their low energy density, low initial coulombic efficiency, and poor cycling lifespan, as well as sluggish sodium diffusion dynamics are still the main issues for the application of intercalation-based anode materials in SIBs in terms of meeting the benchmark requirements for commercialization. Over the past few years, tremendous efforts have been devoted to improving the performance of SIBs. In this Review, recent progress in the development of intercalation-based anode materials, including TiO 2 , Li 4 Ti 5 O 12 , Na 2 Ti 3 O 7 , and NaTi 2 (PO 4 ) 3 , is summarized in terms of their sodium storage performance, critical issues, sodiation/desodiation behavior, and effective strategies to enhance their electrochemical performance. Additionally, challenges and perspectives are provided to further understand these intercalation-based anode materials., (© 2021 Wiley-VCH GmbH.)

Manganese-based Prussian Blue, Na 2-δ Mn[Fe(CN) 6 ] (MnPB), is a good candidate for sodium-ion battery cathode materials due to its high capacity. However, it suffers from severe capacity decay during battery cycling due to the destabilizing Jahn-Teller distortions it undergoes as Mn 2+ is oxidized to Mn 3+ . Herein, the structure is stabilized by a thin epitaxial surface layer of nickel-based Prussian Blue (Na 2-δ Ni[Fe(CN) 6 ]). The one-pot synthesis relies on a chelating agent with an unequal affinity for Mn 2+ and Ni 2+ ions, which prevents Ni 2+ from reacting until the Mn 2+ is consumed. This is a new and simpler synthesis of core-shell materials, which usually needs several steps. The material has an electrochemical capacity of 93 mA h g -1 , of which it retains 96 % after 500 charge-discharge cycles (vs. 37 % for MnPB). Its rate capability is also remarkable: at 4 A g -1 (ca. 55 C) it can reversibly store 70 mA h g -1 , which is also reflected in its diffusion coefficient of ca. 10 -8  cm 2  s -1 . The epitaxial outer layer appears to exert an anisotropic strain on the inner layer, preventing the Jahn-Teller distortions it normally undergoes during de-sodiation., (© 2021 Wiley-VCH GmbH.)

Most of the cathode materials for potassium ion batteries (PIBs) suffer from poor structural stability due to the large ionic radius of K + , resulting in poor cycling stability. Here we report a low-strain potassium-rich K 1.84 Ni[Fe(CN) 6 ] 0.88 ⋅0.49 H 2 O (KNiHCF) as a cathode material for PIBs. The as-prepared KNiHCF cathode can deliver reversible discharge capacity of 62.8 mAh g -1 at 100 mA g -1 , with a high discharge voltage of 3.82 V. It can also achieve a superior rate performance of 45.8 mAh g -1 at 5000 mA g -1 , with a capacity retention of 88.6 % after 100 cycles. The superior performance of KNiHCF cathode results from low-strain de-/intercalation mechanism, intrinsic semiconductor property and low potassium diffusion energy barrier. The high power density and long-term stability of KNiHCF//graphite full cell confirmed the feasibility of K-rich KNiHCF cathode in PIBs. This work provides guidance to develop Prussian blue analogues as cathode materials for PIBs., (© 2021 Wiley-VCH GmbH.)

High initial coulombic efficiency is highly desired because it implies effective interface construction and few electrolyte consumption, indicating enhanced batteries' life and power output. In this work, a high-capacity sodium storage material with FeS 2 nanoclusters (≈1-2 nm) embedded in N, S-doped carbon matrix (FeS 2 /N,S-C) was synthesized, the surface of which displays defects-repaired characteristic and detectable dot-matrix distributed Fe-N-C/Fe-S-C bonds. After the initial discharging process, the uniform ultra-thin NaF-rich (≈6.0 nm) solid electrolyte interphase was obtained, thereby achieving verifiable ultra-high initial coulombic efficiency (≈92 %). The defects-repaired surface provides perfect platform, and the catalysis of dot-matrix distributed Fe-N-C/Fe-S-C bonds to the rapid decomposing of NaSO 3 CF 3 and diethylene glycol dimethyl ether successfully accelerate the building of two-dimensional ultra-thin solid electrolyte interphase. DFT calculations further confirmed the catalysis mechanism. As a result, the constructed FeS 2 /N,S-C provides high reversible capacity (749.6 mAh g -1 at 0.1 A g -1 ) and outstanding cycle stability (92.7 %, 10 000 cycles, 10.0 A g -1 ). Especially, at -15 °C, it also obtains a reversible capacity of 211.7 mAh g -1 at 10.0 A g -1 . Assembled pouch-type cell performs potential application. The insight in this work provides a bright way to interface design for performance improvement in batteries., (© 2021 Wiley-VCH GmbH.)

This work reports influence of two different electrolytes, carbonate ester and ether electrolytes, on the sulfur redox reactions in room-temperature Na-S batteries. Two sulfur cathodes with different S loading ratio and status are investigated. A sulfur-rich composite with most sulfur dispersed on the surface of a carbon host can realize a high loading ratio (72% S). In contrast, a confined sulfur sample can encapsulate S into the pores of the carbon host with a low loading ratio (44% S). In carbonate ester electrolyte, only the sulfur trapped in porous structures is active via 'solid-solid' behavior during cycling. The S cathode with high surface sulfur shows poor reversible capacity because of the severe side reactions between the surface polysulfides and the carbonate ester solvents. To improve the capacity of the sulfur-rich cathode, ether electrolyte with NaNO 3 additive is explored to realize a 'solid-liquid' sulfur redox process and confine the shuttle effect of the dissolved polysulfides. As a result, the sulfur-rich cathode achieved high reversible capacity (483 mAh g -1 ), corresponding to a specific energy of 362 Wh kg -1 after 200 cycles, shedding light on the use of ether electrolyte for high-loading sulfur cathode.

Li-CO 2 batteries are one type of promising energy storage and conversion devices to capture and utilize the greenhouse gas CO 2 , mitigating global temperature rise and climate change. Catalysts that could effectively decompose the discharge product, Li 2 CO 3 , are essential for high-performance Li-CO 2 batteries. Benefiting from the interconnected porous structure, favorable oxygen vacancy, and the synergistic effects between the carbon nanotube (CNT) and layered birnessite δ-MnO 2 , our Li-CO 2 cathodes with the as-prepared CNT@δ-MnO 2 catalyst can efficiently afford a large reaction surface area and abundant active sites, provide sufficient electron/Li + transport pathways, and facilitate electrolyte infiltration and CO 2 diffusion, demonstrating low overpotential and superior cycling stability, which have been proven by both experimental characterization and theoretical computation. It is expected that this work can provide guidance for the design and synthesis of high-performance electrochemical catalysts for Li-CO 2 batteries.

Room-temperature (RT) sodium-sulfur (Na-S) batteries hold great promise for large-scale energy storage due to the advantages of high energy density, low cost, and resource abundance. The research progress on RT Na-S batteries, however, has been greatly hindered by the sluggish kinetics of the sulfur redox reactions. Herein, an elaborate multifunctional architecture, consisting of N-doped carbon skeletons and tunable MoS 2 sulfiphilic sites, is fabricated via a simple one-pot reaction followed by in situ sulfurization. Beyond the physical confinement and chemical binding of polarized N-doped carbonaceous microflowers, the MoS 2 active sites play a key role in catalyzing polysulfide redox reactions, especially the conversion from long-chain Na 2 S n (4 ≤ n ≤ 8) to short-chain Na 2 S 2 and Na 2 S. Significantly, the electrocatalytic activity of MoS 2 can be tunable via adjusting the discharge depth. It is remarkable that the sodiated MoS 2 exhibits much stronger binding energy and electrocatalytic behavior compared to MoS 2 sites, effectively enhancing the formation of the final Na 2 S product. Consequently, the S cathode achieves superior electrochemical performance in RT Na-S batteries, delivering a high capacity of 774.2 mAh g -1 after 800 cycles at 0.2 A g -1 , and an ultrahigh capacity retention with a capacity decay rate of only 0.0055% per cycle over 2800 cycles., (© 2021 Wiley-VCH GmbH.)