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Silicon–based materials are among the highly promising anode candidates for Li–ion batteries owing to their excellent theoretical energy density. However, the huge volume variation makes the application of silicon anode in lithium–ion batteries be full of challenge. Herein, high–performance Si@C@rGO composites anode for lithium–ion batteries are successfully prepared by graphene oxide (GO) uniformly encapsulating resorcinol–formaldehyde resin (RF) coated silicon nanoparticles. The RF‐derived carbon layer can prevent the silicon from direct contact with the electrolyte. Furthermore, the continuous conductive graphene network not only improves the overall electrical conductivity of the composite material, but also can be reversibly deformed with the volume change of silicon during the charging and discharging process, thus greatly improving the structural stability of the anode. The optimal Si@C@rGO‐2 composite provides a high specific capacity of 743.9 mAh g−−1 after 300 cycles at a current density of 1 A g−1. Meanwhile, the material also exhibits good rate performance, showing a good reversible capacity of 719.5 mAh g−1 even at a high current density of 2 A g−1. In addition, this simple and low‐cost strategy of Si@C@rGO anode can provide a design reference for the further development of anode materials in lithium–ion batteries. [ABSTRACT FROM AUTHOR]

Na‐O2 batteries are attractive for energy storage due to their high theoretical energy density. In order to alleviate Na dendrite formation, artificial protective coatings have been widely investigated in Na‐metal batteries (NMBs). Although it can be intuitive to expect transferable Na protection methodologies from NMBs to Na‐O2 batteries, the performance of anode protection coatings in Na‐O2 batteries remains obscure, because Na‐O2 batteries undergo a unique reaction mechanism involving superoxide. Here, the effect of superoxide crossover on the polymeric Na protection layer in Na‐O2 batteries is revealed, and an effective strategy to eliminate the implications of a superoxide‐sensitive protecting layer is proposed. Using polymeric alucone protected Na anode as an example, the alucone layer actually decomposes under superoxide attack and is incapable of facilitating long‐term cycling of Na‐O2 batteries in sharp contrast to its stable performance in NMBs. By blocking superoxide crossover with solid‐state electrolytes (SSEs), significantly improved Na‐O2 cell performance is demonstrated, recovering the Na dendrite suppressing effect of the alucone film. Benefiting from the synergistic effect of SSE and alucone layer, Na‐O2 batteries can achieve a long life of 325 cycles at 0.2 mA cm−2. This work indicates that the stability of the Na protection layer against superoxide should be taken into serious consideration. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries are deemed as optimal energy devices for the next generation of high‐energy‐density energy storage. However, several problems such as low energy density and short cycle life hinder their application in industry. Here, MoS2–MoN heterostructure nanosheets grown on carbon nanotube arrays as free‐standing cathodes are reported. In this heterostructure, MoN works as a promoter to provide coupled electrons to accelerate the redox reaction of polysulfides while the MoS2, with a two‐dimensional layered structure, provides smooth Li+ diffusion pathways. Through their respective advantages, both MoN and MoS2 could mutually boost the process of "adsorption‐diffusion‐conversion" of polysulfides, which have a synergy enhancement effect to restrain the lithium polysulfides from shuttling. The designed cathodes show excellent long‐term cycling performances of 1000 cycles at 1C with a low decay rate of 0.039% per cycle and a high rate capability up to 6C. A high initial areal capacity of 13.3 mAh cm−2 is also achieved under a low electrolyte volume/sulfur loading (E/S) ratio of 6.3 mL g−1. This strategy of promoting polysulfide conversion by heterostructure MoS2–MoN as presented in this work can provide a more structured design strategy for future advanced Li–S energy storage systems. [ABSTRACT FROM AUTHOR]

Solid‐state Li‐O2 batteries possess the ability to deliver high energy density with enhanced safety. However, designing a highly functional solid‐state air electrode is the main bottleneck for its further development. Herein, we adopt a hybrid electronic and ionic conductor to build solid‐state air electrode that makes the transition of Li‐O2 battery electrochemical mechanism from a three‐phase process to a two‐phase process. The solid‐state Li‐O2 battery with this hybrid conductor solid‐state air electrode shows decreased interfacial resistance and enhanced reaction kinetics. The Coulombic efficiency of Li‐O2 battery is also significantly improved, benefiting from the good contact between discharge products and electrode materials. In situ environmental transmission electron microscopy under oxygen was used to illustrate the reversible deposition and decomposition of discharge products on the surface of this hybrid conductor, visually verifying the two‐phase reaction. [ABSTRACT FROM AUTHOR]

Li‐ and Mn‐rich layered oxides are among the most promising cathode materials for Li‐ion batteries with high theoretical energy density. Its practical application is, however, hampered by the capacity and voltage fade after long cycling. Herein, a finite difference method for near‐edge structure (FDMNES) code was combined with in situ X‐ray absorption spectroscopy (XAS) and transmission electron microscopy/electron energy loss spectroscopy (TEM/EELS) to investigate the evolution of transition metals (TMs) in fresh and heavily cycled electrodes. Theoretical modeling reveals a recurring partially reversible LiMn2O4‐like sub‐nanodomain formation/dissolution process during each charge/discharge, which accumulates gradually and accounts for the Mn phase transition. From the modeling of spectra and maps of the valence state over large regions of the cathodes, it was found that the phase change is size‐dependent. After prolonged cycling, the TMs displayed different levels of inactivity. [ABSTRACT FROM AUTHOR]

Abstract: Na‐O2 batteries have attracted extensive attention as promising candidates for large‐scale energy storage due to their ultrahigh theoretical energy density. However, the poor cycling performance of Na‐O2 batteries is one of the major challenges facing its future development. A novel Na‐O2 battery using electrically connected carbon paper with Na metal as a protected anode is presented in this study. The O2− crossover from the cathode to anode partially contributes to the limited Coulombic efficiency, as well as the Na corrosion during the cycling process. For the cells with protected Na, the carbon paper maintains a pseudo‐equal potential with the Na metal and works as an artificial protective layer to suppress the detrimental side reactions caused by O2− and O2 crossover toward the Na electrode. Furthermore, the short‐circuiting issue caused by Na dendrite growth also can be completely resolved. Consequently, the Na‐O2 cells with protected Na exhibit two times higher discharge capacity and cycling stability compared with the cells using bare Na. These results indicate the crucial role of the Na anode in determining the overall cell performance and a rational design of anode can dramatically contribute to develop advanced Na‐O2 batteries with longer lifespans and better cycling performance. [ABSTRACT FROM AUTHOR]

All‐solid‐state lithium‐ion batteries (ASSLIBs) have gained substantial attention worldwide due to their intrinsic safety and high energy density. However, the large interfacial resistance of ASSLIBs, which originates from the interfacial reactions and inferior electrode–electrolyte contact between electrodes and solid electrolytes, dramatically constrains their electrochemical performance. Here a dual shell interfacial nanostructure is rationally designed to enable high‐performance ASSLIBs, in which the inner shell LiNbO3 suppresses the interfacial reactions while the outer shell Li10GeP2S12 enables intimate electrode–electrolyte contact. As a result, the dual shell structured Li10GeP2S12@LiNbO3@LiCoO2 exhibits a high initial specific capacity of 125.8 mAh g−1 (1.35 mAh cm−2) with an initial Coulombic efficiency of 90.4% at 0.1 C and 87.7 mAh g−1 at 1 C. More importantly, in situ X‐ray absorption near edge spectroscopy was performed for the first time to reveal the interfacial reactions between Li10GeP2S12 and LiCoO2. This dual shell nanostructure demonstrates an ideal interfacial configuration for realizing high‐performance ASSLIBs. [ABSTRACT FROM AUTHOR]

Development of Li‐O2 batteries with ultrahigh theoretical energy density is highly desired to meet the ever‐increasing demand of energy density. However, safety concerns and cycling life have become main bottlenecks that inhibit the practical applications of Li‐O2 batteries because of the use of organic liquid electrolytes (LEs) and the noneffective air electrodes. Gel polymer electrolytes (GPEs) are reported to be used in Li‐O2 batteries and show relatively improved performance than LEs, but they are still below the expectation. Herein, a quasi‐solid‐state Li‐O2 battery constructed with a GPE and a high‐efficiency air electrode is proposed. Excellent electrochemical performance is demonstrated beyond the batteries with LE, evidenced by the ultralong cycle life of up to 553 cycles and stable operating time for over 1100 h. The elongated cycling life benefits from the role of GPE in blocking O2 crossover, protecting Li metal, and avoiding electrolyte evaporation compared with LE. It is expected that the present study can shed light on the future study on developing efficient catalysts for (quasi) solid‐state Li‐O2 battery. Quasi‐solid‐state Li‐O2 batteries with an ultralong cycling life of up to 553 cycles are built by pairing an advanced gel polymer electrolyte (GPE) with a high efficiency air electrode. The elongated cycling life benefits from the role of GPE in blocking O2 crossover, protecting Li metal, and suppressing electrolyte evaporation and high catalytic activity of ultrafine RuO2 nanoparticles. [ABSTRACT FROM AUTHOR]