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Electrocatalysts are crucial to drive the electrochemical carbon dioxide reduction reaction (CO2RR) which lower the energy barrier, tune the intricate reaction pathways and suppress competitive side‐reaction. Beyond the efficient active sites and advantageous local environment, a rapid mass transfer ability is also crucial for the catalyst design. However, it is rare that research has been done to investigate in detail the mass transfer process in CO2RR, and expose the underlying relationship between mass transfer and final performance. Here, a single‐atom Fe‐N‐C catalyst is shown with a highly ordered porous substrate containing hierarchical micropores, mesopores, and macropores. Such a delicate porous structure significantly facilitates the mass transfer process toward the isolated Fe sites, achieving excellent CO2RR performance, especially in the limited mass transfer region in a H‐cell with a maximum CO partial current density of ‐19 mA cm−2. Operando electrochemical impedance spectroscopy and relevant distributed relaxation times analysis reveal the rapidly decreased mass transfer resistance with the increase of reduction potential. The Lattice Boltzmann method with Discrete Element method (LBM‐DEM) simulations are further performed to exhibit the origin of enhanced CO2RR performance from the facilitated gas diffusion process. [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]

Polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) are incompatible with the 4 V class cathodes such as LiCoO2 due to the limited electrochemical oxidation window of PEO. Herein, a number of binders including commonly used binders PEO, polyvinylidene fluoride (PVDF), and carboxyl‐rich polymer (CRP) binders such as sodium alginate (Na‐alginate) and sodium carboxymethyl cellulose, are studied for application in the 4 V class all‐solid‐state polymer batteries (ASSPBs). The results show ASSPBs with CRP binders exhibit superior cycling performance up to 1000 cycles (60% capacity retention, almost 10 times higher than those with PEO and PVDF binders). Synchrotron‐based X‐ray absorption spectroscopy (XAS), morphology studies and density functional theory studies indicate that, with their carboxyl groups, CRPs can strongly bind the electrode materials together, and work as coating materials to protect the cathode/SPE interface. Cyclic voltammetry studies indicate that CRP binders are more stable at high voltage compared to PEO and PVDF. The stability under high voltage and the coating property of CRP binders contribute to stable cathode/SPE interfaces as disclosed by the X‐ray photoelectron spectroscopy and Co L‐edge XAS results, enabling long cycling life, high performance 4 V class ASSPBs. [ABSTRACT FROM AUTHOR]

Undesirable Li dendrite growth under high current densities due to the nonuniform Li nucleation and growth has significantly hindered the development of high‐rate all‐solid‐state lithium batteries (ASSLBs). Herein, the phase evolution of a Li prenucleator (MoS2) is shown in working ASSLBs that renders a highly active nucleator (Mo), where Mo promotes fast Li nucleation and Li dendrite suppression. During plating, Li shows strong affinity with Mo, which guides Li fast nucleating and selectively depositing on Mo surface with a large specific surface, thus reducing the local current density. Moreover, a fast diffusion of Li atom on Mo (110) surface promotes uniform Li deposition and limits the Li dendrite growth. Benefitting from the reduced local current density as well as the improved Li dendrite suppression, Li–Li symmetric cells within MoS2 prenucleator demonstrate excellent electrochemical performance, achieving cycle lifetimes as high as 1000 h for 1 mA cm−2/1 mAh cm−2 and 780 h for 0.5 mA cm−2/2 mAh cm−2. Additionally, developed Li‐LFP ASSLBs demonstrate high capacity retention of 78% with an ultra‐long cycling life of 3000 cycles under a high current density of 1 mA cm−2. The general concept has the potential to be extended to other metal‐sulfide prenucleators. [ABSTRACT FROM AUTHOR]

Sulfide‐based solid‐state electrolytes (SSEs) for all‐solid‐state Li metal batteries (ASSLMBs) are attracting significant attention due to their high ionic conductivity, inherently soft properties, and decent mechanical strength. However, the poor incompatibility with Li metal and air sensitivity have hindered their application. Herein, the Sn (IV) substitution for P (V) in argyrodite sulfide Li6PS5I (LPSI) SSEs is reported, in the preparation of novel LPSI‐xSn SSEs (where x is the Sn substitution percentage). Appropriate aliovalent element substitutions with larger atomic radius (R > R) provides the optimized LPSI‐20Sn electrolyte with a 125 times higher ionic conductivity compared to that of the LPSI electrolyte. The high ionic conductivity of LPSI‐20Sn enables the rich I‐containing electrolyte to serve as a stabilized interlayer against Li metal in sulfide‐based ASSLMBs with outstanding cycling stability and rate capability. Most importantly, benefiting from the strong Sn–S bonding in Sn‐substituted electrolytes, the LPSI‐20Sn electrolyte shows excellent structural stability and improved air stability after exposure to O2 and moisture. The versatile Sn substitution in argyrodite LPSI electrolytes is believed to provide a new and effective strategy to achieve Li metal‐compatible and air‐stable sulfide‐based SSEs for large‐scale applications. [ABSTRACT FROM AUTHOR]

Although metallic lithium is regarded as the "Holy Grail" for next‐generation rechargeable batteries due to its high theoretical capacity and low overpotential, the uncontrollable Li dendrite growth, especially under high current densities and deep plating/striping, has inhibited its practical application. Herein, a 3D‐printed, vertically aligned Li anode (3DP‐VALi) is shown to efficiently guide Li deposition via a "nucleation within microchannel walls" process, enabling a high‐performance, dendrite‐free Li anode. Moreover, the microchannels within the microwalls are beneficial for promoting fast Li+ diffusion, supplying large space for the accommodation of Li during the plating/stripping process. The high‐surface‐area 3D anode design enables high operating current densities and high areal capacities. As a result, the Li–Li symmetric cells using 3DP‐VALi demonstrate excellent electrochemical performances as high as 10 mA cm−2/10 mAh cm−2 for 1500 h and 5 mA cm−2/20 mAh cm−2 for 400 h, respectively. Additionally, the Li–S and Li–LiFePO4 cells using 3DP‐VALi anodes present excellent cycling stability up to 250 and 800 cycles at a rate of 1 C, respectively. It is believed that these new findings could open a new window for dendrite‐free metal anode design and pave the way toward energy storage devices with high energy/power density. [ABSTRACT FROM AUTHOR]

Abstract: The intricate charge–discharge reactions and bad conductivity nature of sulfur determine the extreme importance of cathode engineering for Li–S batteries. Herein, spinel ZnCo2O4 porous particles@N‐doped reduced graphene oxide (ZnCo2O4@N‐RGO) are prepared via the combined procedures of refluxing and hydrothermal treatment, consisting of interconnected uniform ZnCo2O4 nanocubes with an average size of 5 nm anchored on graphene nanosheets. The as‐obtained composite can act as an inimitable cathode scaffold to suppress the shuttling of polysulfides by chemical confinement of ZnCo2O4 and N‐RGO for the first time, as demonstrated by the adsorption energy of ZnCo2O4 to Li2S4 via the strong chemical bonding between Zn or Co and S. The RGO nanosheets with a relatively high specific surface area provide a good conductive network and structural stability. The introduction of doped N atoms and numerous ZnCo2O4 porous nanoparticles can inhibit the transfer of lithium polysulfides between the cathode and anode. Due to the unique structural and compositional features, the as‐obtained hybrid materials with the high sulfur loading of 71% and even 82% still deliver high specific capacity, good rate capability, and enhanced cycling stability with exceptionally high initial Coulombic efficiency, which displays a high utilization of sulfur. [ABSTRACT FROM AUTHOR]

Electrocatalysts are crucial to drive the electrochemical carbon dioxide reduction reaction (CO2RR) which lower the energy barrier, tune the intricate reaction pathways and suppress competitive side‐reaction. Beyond the efficient active sites and advantageous local environment, a rapid mass transfer ability is also crucial for the catalyst design. However, it is rare that research has been done to investigate in detail the mass transfer process in CO2RR, and expose the underlying relationship between mass transfer and final performance. Here, a single‐atom Fe‐N‐C catalyst is shown with a highly ordered porous substrate containing hierarchical micropores, mesopores, and macropores. Such a delicate porous structure significantly facilitates the mass transfer process toward the isolated Fe sites, achieving excellent CO2RR performance, especially in the limited mass transfer region in a H‐cell with a maximum CO partial current density of ‐19 mA cm−2. Operando electrochemical impedance spectroscopy and relevant distributed relaxation times analysis reveal the rapidly decreased mass transfer resistance with the increase of reduction potential. The Lattice Boltzmann method with Discrete Element method (LBM‐DEM) simulations are further performed to exhibit the origin of enhanced CO2RR performance from the facilitated gas diffusion process. [ABSTRACT FROM AUTHOR]