Realizing long-life cycling is the biggest challenge in the research field of Li-O2 batteries in the current stage. The main reasons for poor cycling performance are the sluggish Li2O2 formation and decomposition process, as well as the side reaction of carbon cathode. In order to accurately address the problems above, a TiO2/CNTs cathode was rationally designed for long-life Li-O2 batteries. The CNTs skeleton offers multiple three-dimensional channels for the rapid transportation of oxygen, Li+ and electrons. A thin-film and discontinuous layer of TiO2 is coated on the CNTs surface to effectively inhibit the carbon corrosion but still could let mass transfer smoothly. Ultrafine Ru nanoparticles decorating the TiO2/CNTs serve as efficient catalytic active sites. Benefiting from the unique structure design, Li-O2 batteries with the cathode of TiO2/CNTs achieve a cycling life of 110 with a fixed capacity of 500 mAh g-1 at a current density of 100 mA g-1. Our research generates new ideas for designing long-cycling Li-O2 battery cathodes.
Inorganic metal halide perovskites such as CsPbX3 (X = I, Br) have been intensively studied in optoelectrical applications such as solar cells and light-emitting diodes due to better thermal and structural stability compared to the organic-inorganic hybrid perovskite counterparts. Limited studies have shown that inorganic perovskites could potentially be promising electrode materials in energy storage devices like supercapacitors. Nevertheless, there is some controversy regarding their electrochemical properties and energy storage mechanism. Furthermore, the stability of the inorganic perovskites in electrochemical energy storage systems is a big concern. In this work, we studied the electrochemical properties of CsPbBr3 electrodes composed of pure CsPbBr3 nanocrystals without any additives to reveal their intrinsic electrochemical characteristics. We carefully selected the electrolyte solution composed of tetrabutylammonium hexafluorophosphate in dichloromethane and the electrode substrate based on FTO glass to ensure they do not cause damage to the perovskite material or introduce side reactions during the charge-discharge process. The results showed that the CsPbBr3 perovskite demonstrates electrical double-layer capacitive behaviour, and the specific capacitance of the electrode can reach 528 mF g-1. A symmetrical supercapacitor based on this perovskite demonstrated exceptional cycling stability with a capacitance retention of 90% after 10,000 charge and discharge cycles at a discharge current density of 100 mA g-1. The device also exhibited a constant power density of 25.0 mW kg-1 with increasing energy density up to 33.3 mWh kg-1. Further characterizations have revealed the important role of the large cations and anions of tetrabutylammonium hexafluorophosphate in the electrolyte in stabilizing the perovskite electrode material.
The development of various high-performance electrochemical devices is crucial for mitigating the global climate crisis, and thus the design and fabrication of advanced electrode materials is highly significant. Currently, atomically dispersed metal on catalysts (ADMCs) have shown great potential in boosting the performance of various energy storage/conversion devices involving aqueous and aprotic catalytic processes, including fuel cells, water electrolyzers, CO2 electrolyzers, metal-air batteries, and metal-sulfur batteries, as well as systems involving noncatalytic deposition/adsorption of metals. To date, several reliable fabrication methodologies that can ensure the formation of ADMCs have been demonstrated, and continuous optimization is still being performed. To further reinforce the basic scientific research and promote possible practical applications of these materials, we have analyzed, compared, and summarized progress in the fabrication methodology and formation mechanism of ADMCs in this review. This review aims to draw a comprehensive picture of the current methodology and underlying mechanism in the field of material fabrication to serve as guidance for future material design.
Mildly acidic aqueous zinc (Zn) batteries are promising for large-energy storage but suffer from the irreversibility of Zn metal anodes due to parasitic H2 evolution, Zn corrosion, and dendrite growth. In recent years, increasing efforts have been devoted to overcoming these obstacles by regulating electrolyte structures. In this review, we investigate progress towards mildly acidic aqueous electrolytes for Zn batteries, with special emphasis on how the microstructures (in the bulk phase and on the surface of Zn anodes) affect the performance of Zn anodes. Moreover, effective computational simulations and characterization measurements for the structures of bulk electrolytes and Zn/electrolyte interfaces are discussed, along with perspectives for the direction of further investigations.
The energy density of lithium-ion batteries based on intercalated electrode materials has reached its upper limit, which makes it challenging to meet the growing demand for high-energy storage systems. Electrode materials based on conversion reactions such as sulfur, organosulfides, and oxygen involving breakage and reformation of chemical bonds can provide higher specific capacity and energy density. In addition, they usually consist of abundant elements, making them renewable. Although they have the aforementioned benefits, they face numerous challenges for practical applications. For example, the cycled products of sulfur and molecular organosulfides could be soluble in a liquid electrolyte, resulting in the shuttle effect and significant capacity loss. The discharged product of oxygen is Li2O2, which could result in high charge overpotential and decomposition of the electrolyte. In this review, we present an overview of the current strategies for improving the performances of lithium-sulfur, lithium-organosulfide, and lithium-oxygen batteries. First, we summarize the efforts to overcome the issues facing sulfur and organosulfide cathodes, as well as the strategies to increase the capacity of organosulfides. Then, we introduce the latest research progress on catalysts in lithium-oxygen batteries. Finally, we summarize and provide outlooks for the conversion of electrode materials.
Single-atom catalysts (SACs) with high activity, unique selectivity, and nearly 100% atom utilization efficiency are promising for broad applications in many fields. This review aims to provide a summary of the current development of SACs and point out their challenges and opportunities for commercial applications in the energy process. The discussion starts with an introduction of various types of SACs materials, followed by typical SACs synthetic methods with concrete examples and commonly used characterization methods. The state-of-the-art synthesis methods, whereby SACs with stabilized single metal atoms on the substrate without migration and agglomeration could be obtained, are emphasized. Next, we give an overview of different types of substrates and discuss the effects of substrate species on the structure and properties of SACs. Then we highlight the typical applications of SACs and the remaining challenges. Finally, a perspective on the opportunities for the development of SACs for future commercial applications is provided.
Polymer/ceramic composite electrolytes have recently received a lot of attention because they combine the advantages of high ionic conductivity of inorganic ceramics and the inherent elasticity of polymer constituents. Nonetheless, the interaction between the ceramic particles and the polar functional groups on the polymer molecules would affect the ion transport rate, which is an important factor to consider when developing a polymer/ceramic composite electrolyte. We present a composite elastic electrolyte based on polyurethane (PU) with high ionic conductivity of 10-3 S/cm and excellent mechanical properties (stress-strain) of 4.5 MPa by incorporating ceramic particles into the ion conduction chains on PU. This method improves the interaction between PU/LGPS and Li+ ions and the conduction of Li+ ions at the bi-phase interface, yielding a high Li+ transfer number of 0.56. After 2,000 cycles, the capacity retention rates of the batteries assembled by
Heteroatom-doped carbon materials have high gravimetric potassium-ion storage capability because of their abundant active sites and defects. However, their practical applications toward potassium storage are limited by sluggish reaction kinetics and short cycling life owing to the large ionic radius of K+ and undesirable parasitic reactions. Herein, we report a new strategy that allows for bottom-up patterning of thin N/P co-doped carbon layers with a uniform mesoporous structure on two-dimensional graphene sheets. The highly porous architecture and N/P co-doping properties provide abundant active sites for K+, and the graphene sheets promote charge/electron transfer. This synergistic structure enables excellent K+ storage performance in terms of specific capacity (387.6 mAh g-1 at 0.05 A g-1), rate capability (over 5 A g-1), and cycling stability (70% after 3,000 cycles). As a proof of concept, a potassium-ion capacitor assembled using this carbon anode yields a high energy density of 107 Wh kg-1, a maximum power density of 18.3 kW kg-1, and ultra-long cycling stability over 40,000 cycles.
Solid-state batteries (SSBs) based on inorganic solid electrolytes (ISEs) are considered promising candidates for enhancing the energy density and the safety of next-generation rechargeable lithium batteries. However, their practical application is frequently hampered by the high resistance arising at the Li metal anode/ISE interface. Herein, a review of the conventional solid-state electrolytes (SSEs) the recent research on quasi-solid-state battery (QSSB) approaches to overcome the issues of the state-of-the-art SSBs is reported. The feasibility of ionic liquid (IL)-based interlayers to improve ISE/Li metal wetting and enhance charge transfer at solid electrolyte interfaces with both positive and lithium metal electrodes is presented together with a novel generation of IL-containing quasi-solid-state-electrolytes (QSSEs), offering favourable features. The opportunities and challenges of QSSE for the development of high energy and high safety quasi-solid-state lithium metal batteries (QSSLMBs) are also discussed.