Sodium‐ion batteries (SIBs) have huge potential for applications in large‐scale energy storage systems due to their low cost and abundant sources. It is essential to develop new electrode materials ...for SIBs with high performance in terms of energy density, cycle life, and cost. Metal binary compounds that operate through conversion reactions hold promise as advanced anode materials for sodium storage. This Review highlights the storage mechanisms and advantages of conversion‐type anode materials and summarizes their recent development. Although conversion‐type anode materials have high theoretical capacities and abundant varieties, they suffer from multiple challenging obstacles to realize commercial applications, such as low reversible capacity, large voltage hysteresis, low initial coulombic efficiency, large volume changes, and low cycling stability. These key challenges are analyzed in this Review, together with emerging strategies to overcome them, including nanostructure and surface engineering, electrolyte optimization, and battery configuration designs. This Review provides pertinent insights into the prospects and challenges for conversion‐type anode materials, and will inspire their further study.
Metal binary compounds that exhibit conversion reactions offer huge potential as advanced anode materials for sodium storage. This Review highlights the storage mechanisms and advantages of conversion‐type anode materials and summarizes their recent development. The key challenges associated with conversion reactions are analyzed in this Review, together with emerging strategies to overcome them.
Rechargeable sodium‐ion batteries (SIBs), as the most promising alternative to commercial lithium‐ion batteries, have received tremendous attention during the last decade. Among all the anode ...materials for SIBs, metal sulfides/selenides (MXs) have shown inspiring results because of their versatile material species and high theoretical capacity. They suffer from large volume expansion, however, which leads to bad cycling performance. Thus, methods such as carbon modification, nanosize design, electrolyte optimization, and cut‐off voltage control are used to obtain enhanced performance. Here, recent progress on MXs is summarized in terms of arranging the crystal structure, synthesis methods, electrochemical performance, mechanisms, and kinetics. Challenges are presented and effective ways to solve the problems are proposed, and a perspective for future material design is also given. It is hoped that light is shed on the development of MXs to help finally find applications for next‐generation rechargeable batteries.
Metal sulfides and metal selenides have shown great progress as anode materials for sodium‐ion batteries because of their versatile material species, easily controlled morphology, and high theoretical specific capacity. Their advances and challenges are summarized, showing their importance for next‐generation energy storage and conversion devices.
Developing sustainable and renewable energy sources along with efficient energy storage and conversion technologies is vital to address environmental and energy challenges. Electrochemical water ...splitting coupling with grid‐scale renewable energy harvesting technologies is becoming one of the most promising approaches. Besides, hydrogen with the highest mass‐energy density of any fuel is regarded as the ultimate clean energy carrier. The realization of practical water splitting depends heavily on the development of low‐cost, highly active, and durable catalysts for hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs). Recently, heterostructured catalysts, which are generally composed of electrochemical active materials and various functional additives, have demonstrated extraordinary electrocatalytic performance toward HER and OER, and particularly a number of precious‐metal‐free heterostructures delivered comparable activity with precious‐metal‐based catalysts. Herein, an overview is presented of recent research progress on heterostructured HER catalysts. It starts with summarizing the fundamentals of HER and approaches for evaluating HER activity. Then, the design and synthesis of heterostructures, electrochemical performance, and the related mechanisms for performance enhancement are discussed. Finally, the future opportunities and challenges are highlighted for the development of heterostructured HER catalysts from the points of view of both fundamental understandings and practical applications.
Recent research progress on heterostructured catalysts for electrochemical hydrogen evolution reaction (HER) is summarized in terms of materials design and synthesis, electrochemical performance, and the related mechanisms for performance enhancement. This review not only provides new insights into designing low‐cost and highly active HER catalysts, but also sheds light on developing functional heterostructures toward a wide range of catalysis applications.
The aprotic lithium–oxygen (Li–O2) battery has excited huge interest due to it having the highest theoretical energy density among the different types of rechargeable battery. The facile achievement ...of a practical Li–O2 battery has been proven unrealistic, however. The most significant barrier to progress is the limited understanding of the reaction processes occurring in the battery, especially during the charging process on the positive electrode. Thus, understanding the charging mechanism is of crucial importance to enhance the Li–O2 battery performance and lifetime. Here, recent progress in understanding the electrochemistry and chemistry related to charging in Li–O2 batteries is reviewed along with the strategies to address the issues that exist in the charging process at the present stage. The properties of Li2O2 and the mechanisms of Li2O2 oxidation to O2 on charge are discussed comprehensively, as are the accompanied parasitic chemistries, which are considered as the underlying issues hindering the reversibility of Li–O2 batteries. Based on the detailed discussion of the charging mechanism, innovative strategies for addressing the issues for the charging process are discussed in detail. This review has profound implications for both a better understanding of charging chemistry and the development of reliable rechargeable Li–O2 batteries in the future.
Addressing the challenges facing lithium–oxygen (Li–O2) batteries during charging is of great significance for improving the performance of Li–O2 batteries. A fundamental discussion on the science underpinning the charging chemistry of the Li–O2 system and on promising strategies for improving these reactions is presented. The findings have deep implications for the future development of reliable rechargeable Li–O2 batteries.
With the unprecedentedly increasing demand for renewable and clean energy sources, the sodium‐ion battery (SIB) is emerging as an alternative or complementary energy storage candidate to the present ...commercial lithium‐ion battery due to the abundance and low cost of sodium resources. Layered transition metal oxides and Prussian blue analogs are reviewed in terms of their commercial potential as cathode materials for SIBs. The recent progress in research on their half cells and full cells for the ultimate application in SIBs are summarized. In addition, their electrochemical performance, suitability for scaling up, cost, and environmental concerns are compared in detail with a brief outlook on future prospects. It is anticipated that this review will inspire further development of layered transition metal oxides and Prussian blue analogs for SIBs, especially for their emerging commercialization.
Layered transition metal oxides and Prussian blue analogs are reviewed in terms of their commercial potential as cathode materials for sodium‐ion batteries. Recent research progresses, and their electrochemical performance, scale‐up availability, cost, and environmental concerns are discussed in detail and prospected. It is anticipated that this review could inspire the development and provide guidance for their emerging commercialization.
Sodium‐ion batteries (SIBs) are attracting increasing attention and considered to be a low‐cost complement or an alternative to lithium‐ion batteries (LIBs), especially for large‐scale energy ...storage. Their application, however, is limited because of the lack of suitable host materials to reversibly intercalate Na+ ions. Layered transition metal oxides (NaxMO2, M = Fe, Mn, Ni, Co, Cr, Ti, V, and their combinations) appear to be promising cathode candidates for SIBs due to their simple structure, ease of synthesis, high operating potential, and feasibility for commercial production. In the present work, the structural evolution, electrochemical performance, and recent progress of NaxMO2 as cathode materials for SIBs are reviewed and summarized. Moreover, the existing drawbacks are discussed and several strategies are proposed to help alleviate these issues. In addition, the exploration of full cells based on NaxMO2 cathodes and future perspectives are discussed to provide guidance for the future commercialization of such systems.
Layered transition metal oxides have attracted increasing interests as cathode materials for sodium‐ion batteries. Recent progresses of NaxMO2 cathodes, including the existing drawbacks and relative alleviation strategies, are reviewed and summarized. The exploration of full cells based on NaxMO2 cathodes and future perspectives are also discussed to provide guidance for the future commercialization of such systems.
Prussian blue analogues (PBAs, A2TM(CN)6, A = Li, K, Na; T = Fe, Co, Ni, Mn, Cu, etc.; M = Fe, Mn, Co, etc.) are a large family of materials with an open framework structure. In recent years, they ...have been intensively investigated as active materials in the field of energy conversion and storage, such as for alkaline‐ion batteries (lithium‐ion, LIBs; sodium‐ion, NIB; and potassium‐ion, KIBs), and as electrochemical catalysts. Nevertheless, few review papers have focused on the intrinsic chemical and structural properties of Prussian blue (PB) and its analogues. In this Review, a comprehensive insight into the PBAs in terms of their structural and chemical properties, and the effects of these properties on their materials synthesis and corresponding performance is provided.
This Review provides a comprehensive overview of the latest research progress on Prussian blue analogues (PBAs), including the synthesis methods, structural and chemical properties of PBAs, various applications for these PBAs, and the effects of their structural and chemical properties on material synthesis and applications. Finally, some personal viewpoints on the challenges and outlook for PBAs application are included.
Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is highly challenging for hydrogen production from water splitting, due to the high energy barrier for OO bond formation ...and the restriction of the scaling relation between the multiple reaction intermediates. In order to simultaneously address these concerns, an Ir/Ni(OH)2 heterostructure with abundant heterointerfaces is deliberately designed as an efficient electrocatalyst system, with Ir nanoparticles (NPs) homogeneously confined on the Ni(OH)2 nanosheets. The strong electronic interaction and chemical bonding across the interface between the Ir and Ni(OH)2 can effectively stabilize the metastable electrophilic Ir(V) species, which is vital to boost the formation of OO bonds. Meanwhile, the adsorption of the multiple intermediates is synergistically optimized at the heterointerface, which breaks the restrictive scaling relation and substantially accelerates the OER kinetics. In addition, the severe agglomeration of Ir species is greatly mitigated by the confinement effect, ensuring the structural integrity of the catalyst and the constant exposure of active sites. Owing to its well‐defined multifunctional interfaces, the Ir/Ni(OH)2 heterostructure exhibits exceptional OER activity and durability in alkaline media. The present results highlight the significance of heterostructure interface engineering toward the rational design and development of advanced electrocatalysts for the OER and beyond.
A highly efficient Ir/Ni(OH)2 heterostructured electrocatalyst is designed for the oxygen evolution reaction (OER). The heterointerface not only stabilizes the metastable electrophilic Ir(V) species but also breaks the scaling relation, thereby substantially promoting the OER kinetics. The results highlight the significance of heterostructure interface engineering toward the rational design of advanced electrocatalysts for the OER and beyond.
Iron-based Prussian blue analogs are promising low-cost and easily prepared cathode materials for sodium-ion batteries. Their materials quality and electrochemical performance are heavily reliant on ...the precipitation process. Here we report a controllable precipitation method to synthesize high-performance Prussian blue for sodium-ion storage. Characterization of the nucleation and evolution processes of the highly crystalline Prussian blue microcubes reveals a rhombohedral structure that exhibits high initial Coulombic efficiency, excellent rate performance, and cycling properties. The phase transitions in the as-obtained material are investigated by synchrotron in situ powder X-ray diffraction, which shows highly reversible structural transformations between rhombohedral, cubic, and tetragonal structures upon sodium-ion (de)intercalations. Moreover, the Prussian blue material from a large-scale synthesis process shows stable cycling performance in a pouch full cell over 1000 times. We believe that this work could pave the way for the real application of Prussian blue materials in sodium-ion batteries.
Direct methanol fuel cells (DMFCs) are among the most promising portable power supplies because of their unique advantages, including high energy density/mobility of liquid fuels, low working ...temperature, and low emission of pollutants. Various metal‐based anode catalysts have been extensively studied and utilized for the essential methanol oxidation reaction (MOR) due to their superior electrocatalytic performance. At present, especially with the rapid advance of nanotechnology, enormous efforts have been exerted to further enhance the catalytic performance and minimize the use of precious metals. Constructing multicomponent metal‐based nanocatalysts with precisely designed structures can achieve this goal by providing highly tunable compositional and structural characteristics, which is promising for the modification and optimization of their related electrochemical properties. The recent advances of metal‐based electrocatalytic materials with rationally designed nanostructures and chemistries for MOR in DMFCs are highlighted and summarized herein. The effects of the well‐defined nanoarchitectures on the improved electrochemical properties of the catalysts are illustrated. Finally, conclusive perspectives are provided on the opportunities and challenges for further refining the nanostructure of metal‐based catalysts and improving electrocatalytic performance, as well as the commercial viability.
Efficient catalysts are critical for the electrocatalytic oxidation reaction of methanol. Metal‐based anode catalysts with well‐defined nanoarchitectures and optimal chemical compositions can provide superior performance with lower costs. The possible effects, challenges, and future development are elaborately discussed to shed light on the further design of metal‐based anode catalysts for the methanol electro‐oxidation reaction, leading to a renewable energy supply future.
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