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Lithium‐sulfur (Li−S) batteries have many advantages but still face problems such as retarded polysulfides redox kinetics and Li dendrite growth. Most reported single atom catalysts (SACs) for Li−S batteries are based on d‐band transition metals whose d orbital constitutes active valence band, which is inclined to occur catalyst passivation. SACs based on 4f inner valence orbital of rare earth metals are challenging for their great difficulty to be activated. In this work, we design and synthesize the first rare earth metal Sm SACs which has electron‐rich 4f inner orbital to promote catalytic conversion of polysulfides and uniform deposition of Li. Sm SACs enhance the catalysis by the activated 4f orbital through an f‐d‐p orbital hybridization. Using Sm‐N3C3 modified separators, the half cells deliver a high capacity over 600 mAh g−1 and a retention rate of 84.3 % after 2000 cycles. The fabricated Sm‐N3C3‐Li|Sm‐N3C3@PP|S/CNTs full batteries can provide an ultra‐stable cycling performance of a retention rate of 80.6 % at 0.2 C after 100 cycles, one of the best full Li−S batteries. This work provides a new perspective for the development of rare earth metal single atom catalysis in electrochemical reactions of Li−S batteries and other electrochemical systems for next‐generation energy storage. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries (LSBs) are widely regarded as promising next‐generation batteries due to their high theoretical specific capacity and low material cost. However, the practical applications of LSBs are limited by the shuttle effect of lithium polysulfides (LiPSs), electronic insulation of charge and discharge products, and slow LiPSs conversion reaction kinetics. Accordingly, the introduction of catalysts into LSBs is one of the effective strategy to solve the issues of the sluggished LiPS conversion. Because of their nearly 100% atom utilization and high electrocatalytic activity, single‐atom catalysts (SACs) have been widely used as reaction mediators for LSBs' reactions. Excitingly, the SACs with asymmetric coordination structures have exhibited intriguing electronic structures and superior catalytic activities when compared to the traditional M–N4 active sites. In this review, we systematically describe the recent advancements in the installation of asymmetrically coordinated single‐atom structure as reactions catalysts in LSBs, including asymmetrically nitrogen coordinated SACs, heteroatom coordinated SACs, support effective asymmetrically coordinated SACs, and bimetallic coordinated SACs. Particularly noteworthy is the discussion of the catalytic conversion mechanism of LiPSs spanning asymmetrically coordinated SACs. Finally, a perspective on the future developments of asymmetrically coordinated SACs in LSB applications is provided. [ABSTRACT FROM AUTHOR]

Zinc-based aqueous dual-ion batteries (ADIBs) with halogen-graphite intercalation compound positive electrodes are among the most competitive candidates for next-generation electrochemical energy storage systems. However, most of the electrolytes employed have been gel-like electrolytes; hence, a fundamental understanding of the halogen storage process using fluid hydrates will be essential for constructing efficient Zn-based ADIBs. Herein, the halogen storage mechanism on a graphite electrode from fluid ZnCl2/ZnBr2 hydrates is studied by experimental and computational methods. The results indicate that the halogen storage mechanism is a competition between conversion and intercalation. Moreover, the macroscopic electrode reaction is determined by both the ion-pair solvation state at the graphite–electrolyte interface and the subsequent reactant supply is influenced by the electrode reaction rate. [ABSTRACT FROM AUTHOR]

Tin diselenide, a promising anode material for sodium ion batteries (SIBs), still faces sluggish Na+ diffusion kinetics and severe volume change, resulting in undesirable cycling stability and rate capability. Heterostructure construction is an effective strategy for boosting Na+ storage of SnSe2. Herein, an appealing yolk‐shell nanostructure of SnSe2/NiSe2 heterointerface with rich Se vacancies embedded into N‐doped carbon (SnSe2/NiSe2@NC) is precisely designed through a facile hydrothermal process followed by a selenization strategy. The experimental studies coupled with theoretical calculations results verify that the heterostructure interfaces and Se vacancies accelerate the charge and Na+ transfer efficiency, improve Na+ adsorption energy and supply ample active sites. The yolk‐shell nanostructure and N‐doped carbon buffer the volume variation and improve the structural stability of the electrode material during sodium storage processes. The SnSe2/NiSe2@NC delivers ultra‐long term cycling stability (322.7 mAh g−1 after 7500 cycles at 3 A g−1) and exceptional rate capability (314.6 mAh g−1 at 10 A g−1). The Na‐ion storage mechanism of SnSe2/NiSe2@NC is explored through in situ X‐ray diffraction and ex situ high‐resolution transmission electron microscopy analysis. The present work provides an effective avenue to the rational design of heterostructure anode materials for high efficiency SIBs. [ABSTRACT FROM AUTHOR]

With the rapid development of new energy sources, proton-exchange membrane fuel cells (PEMFCs) have been increasingly recognized and promoted. There are many device-level and infrastructure-related challenges that need to be overcome before widespread commercialization can be achieved, one of the most critical being increasing the power density of PEMFCs. In this review, the technical development direction of the next generation of high power density PEMFCs is proposed. We present the latest progress related to the design of PEMFCs with high specific power density, focusing on catalysts, proton exchange membranes, gas diffusion layers, and bipolar plates. The challenges and future development trends associated with high-specific-power-density PEMFCs are also presented, providing insight for further improving the power density of PEMFCs. [ABSTRACT FROM AUTHOR]

Solar energy‐driven CO2 reduction and H2 evolution is considered as a very promising pathway to address energy shortage and environmental issues. Multivariate metal organic frameworks (MTV‐MOFs) as a class of distinctive crystal porous materials are assembled from different metals or different ligands via one pot reaction or postsynthesis approach. Recently, MTV‐MOFs have gathered significantly interest in the field of photocatalytic CO2 reduction and H2 evolution owing to their excellent structural stability, tailorable light‐absorption, and catalytic abilities. In this review, incorporating different functional ligands or metals into the parent MOFs are focused on to boost the photocatalytic performance of MTV‐MOFs. First, the synthesis and unique advantages of MTV‐MOF‐based photocatalysts are introduced. Next, an overview on the recent advance on MTV‐MOFs for solar‐to‐chemical energy conversion is summarized into three main categories, consisting of mixed‐metal MOFs, mixed‐ligand MOFs, and mixed‐metal and mixed‐ligand MOFs. Finally, future perspectives and challenges in CO2 conversion and H2 evolution over MTV‐MOF‐based photocatalysts are presented. [ABSTRACT FROM AUTHOR]

Transition metal selenides (TMSes) are considered promising candidates for the anodes of sodium‐ion batteries (SIBs) due to their substantial theoretical capacity. However, TMSes still face with inferior cycling lifespan caused by sluggish Na+ diffusion kinetics and vigorous volume variations during dis/charge processes. Engineering heterostructure is an attractive solution for rapid Na+ transfer, and introducing carbonaceous materials also facilitates enhanced conductivity and structural stability. Herein, CoSe/MoSe2 heterostructure combined with homogeneous carbon composites are rational designed. The kinetic analysis and theoretical calculations verified that heterointerface engineering induced build‐in electric field effect can amplifies the Na+ diffusion kinetics, while carbon contributes to enhanced electrical conductivity and structural stability. Expectedly, the CoSe/MoSe2‐C exhibits high capacity and extremely ultra‐long lifespan (320.9 mAh g−1 at 2.0 A g−1 over 10,000 cycles with an average decay of only 0.01781 mAh g−1 per cycle). Furthermore, in situ X‐ray diffraction (XRD), ex situ X‐ray photoelectorn (XPS), and high‐resolution electron microscopy (HRTEM) are exploited to explore the Na+ storage mechanism. In addition, the Na3V2(PO4)3@rGO//CoSe/MoSe2‐C (NVP@rGO//CoSe/MoSe2‐C) pouch‐type full‐cells are successfully assembled and delivered satisfactory performance. This research presents a viable strategy for the targeted engineering of TMSes aimed at enhancing the efficiency of SIBs. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries have many advantages but still face problems such as retarded polysulfides redox kinetics and Li dendrite growth. Most reported single atom catalysts (SACs) for Li-S batteries are based on d-band transition metals whose d orbital constitutes active valence band, which is inclined to occur catalyst passivation. SACs based on 4f inner valence orbital of rare earth metals are challenging for their great difficulty to be activated. In this work, we design and synthesize the first rare earth metal Sm SACs which has electron-rich 4f inner orbital to promote catalytic conversion of polysulfides and uniform deposition of Li. Sm SACs enhance the catalysis by the activated 4f orbital through an f-d-p orbital hybridization. Using Sm-N 3 C 3 modified separators, the half cells deliver a high capacity over 600 mAh g -1 and a retention rate of 84.3 % after 2000 cycles. The fabricated Sm-N 3 C 3 -Li|Sm-N 3 C 3 @PP|S/CNTs full batteries can provide an ultra-stable cycling performance of a retention rate of 80.6 % at 0.2 C after 100 cycles, one of the best full Li-S batteries. This work provides a new perspective for the development of rare earth metal single atom catalysis in electrochemical reactions of Li-S batteries and other electrochemical systems for next-generation energy storage., (© 2024 Wiley-VCH GmbH.)

Zinc-based aqueous dual-ion batteries (ADIBs) with halogen-graphite intercalation compound positive electrodes are among the most competitive candidates for next-generation electrochemical energy storage systems. However, most of the electrolytes employed have been gel-like electrolytes; hence, a fundamental understanding of the halogen storage process using fluid hydrates will be essential for constructing efficient Zn-based ADIBs. Herein, the halogen storage mechanism on a graphite electrode from fluid ZnCl 2 /ZnBr 2 hydrates is studied by experimental and computational methods. The results indicate that the halogen storage mechanism is a competition between conversion and intercalation. Moreover, the macroscopic electrode reaction is determined by both the ion-pair solvation state at the graphite-electrolyte interface and the subsequent reactant supply is influenced by the electrode reaction rate.