Developing solid-state ionic conductors with desirable charge-transport efficiency and reasonable durability is a fundamental and long-lasting challenge for solid-oxide fuel cells (SOFCs). Ceria-based electrolytes, as one of the most common types of electrolytes for intermediate-temperature solid-oxide fuel cells (IT-SOFCs), offer a high surface-exchange coefficient and faster kinetics in the triple phase boundaries (TPBs); however, they suffer to some extent of electronic conductivity in the reducing atmosphere and gradual phase transitions. Here in this work, we have reported a novel co-doped IT-SOFC electrolyte composite combining the apatite structure of Lanthanum Silicate (LSO) with the fluorite structure of Gadolinium-doped Ceria (GDC), which showed a high ionic conductivity and a minimal electronic leak. The resulting GDC-LSO composite electrolyte also achieved an OCV (open-circuit voltage) of 1 V at 800 degrees C, implying a significant improvement in the OCV values reported for the typical ceria-based electrolytes (similar to 0.75 V). The sample was prepared using 40 wt% GDC and 60 wt% LSO (40GDC-60LSO) showed a maximum electrical conductivity of 25 mS cm(-1) at 800 degrees C with good densification properties (>95 % relative density). The cell electrochemical performance measurement was conducted using a 3.0 vol% humified H-2 stream at the anode side while the cathode side was exposed to the air at 800 degrees C. The interdiffusion of cations between La3+ in the LSO phase and Ce4+ and Gd3+ in the GDC phase was detected by XRD and EDX results after sintering samples at 1500 degrees C for 4 h using 0.5 wt% PVA or 0.5 wt% Ethyl cellulose (EC) as the binder. The proposed GDC-LSO composite could help better understand the influence of compositional constituents and processing variables on the densification and electrical properties of the electrolyte materials for the IT-SOFCs.

The emerging of single-atom catalysts (SACs) offers a great opportunity for the development of advanced energy storage and conversion devices due to their excellent activity and durability, but the actual mass production of high-loading SACs is still challenging. Herein, a facile and green boron acid (H3BO3)-assisted pyrolysis strategy is put forward to synthesize SACs by only using chitosan, cobalt salt and H3BO3 as precursor, and the effect of H3BO3 is deeply investigated. The results show that molten boron oxide derived from H3BO3 as ideal high-temperature carbonization media and blocking media play important role in the synthesis process. As a result, the acquired Co/N/B tri-doped porous carbon framework (Co-N-B-C) not only presents hierarchical porous structure, large specific surface area and abundant carbon edges but also possesses high-loading single Co atom (4.2 wt.%), thus giving rise to outstanding oxygen catalytic performance. When employed as a catalyst for air cathode in Zn-air batteries, the resultant Co-N-B-C catalyst shows remarkable power density and long-term stability. Clearly, our work gains deep insight into the role of H3BO3 and provides a new avenue to synthesis of high-performance SACs.

Hydrogen, known for its renewable nature, high energy utilization efficiency, and clean combustion, holds significant importance as a component in future energy systems. However, the development of an economical, safe, and efficient method for hydrogen storage remains a formidable challenge. In recent decades, researchers have made significant progress in achieving reversible hydrogen absorption and release using various metal hydrides. Among them, magnesium hydride (MgH2) has attracted considerable attention for its high energy density, low cost, and good reversibility. Nevertheless, the high hydrogen absorption and desorption temperature, sluggish kinetic properties, and poor cycling performance of MgH2 remain as the bottlenecks for its practical application. To mitigate these deficiencies, significant research efforts have been focused on the development of carbon-based materials as a means of preparing multifunctional materials. Carbon-based materials have demonstrated great potential in facilitating synergistic modification strategies, such as nanosizing, catalytic effects, and spatial confinement, which have been proven effective in enhancing the hydrogen storage performance of MgH2. In this paper, we present a comprehensive overview of various carbon-based materials, highlighting their unique properties and their contribution to improving hydrogen storage within MgH2 matrices. To be specific, we have been systematically reviewed the synergistic impacts of carbon materials, metal-organic frameworks, transition metal carbides (MXenes), and their respective composites on enhancing the hydrogen storage performance of MgH2. Additionally, this study underscores the benefits of utilizing multifunctional carbon-based materials as modifiers for MgH2 and proposes potential avenues for academic research.

Solid-state lithium batteries (SSLBs) have been broadly accepted as a promising candidate for the next generation lithium-ion batteries (LIBs) with high energy density, long duration, and high safety. The intrinsic non-flammable nature and electrochemical/thermal/mechanical stability of solid electrolytes are expected to fundamentally solve the safety problems of conventional LIBs. However, thermal degradation and thermal runaway could also happen in SSLBs. For example, the large interfacial resistance between solid electrolytes and electrodes could aggravate the joule heat generation; the anisotropic thermal diffusion could trigger the uneven temperature distribution and formation of hotspots further leading to lithium dendrite growth. Considerable research efforts have been devoted to exploring solid electrolytes with outstanding performance and harmonizing interfacial incompatibility in the past decades. There have been fewer comprehensive reports investigating the thermal reaction process, thermal degradation, and thermal runaway of SSLBs. This review seeks to highlight advanced thermal-related analysis techniques for SSLBs, by focusing particularly on multiscale and multidimensional thermal-related characterization, thermal monitoring techniques such as sensors, thermal experimental techniques imitating the abuse operating condition, and thermal-related advanced simulations. Insightful perspectives are proposed to bridge fundamental studies to technological relevance for better understanding and performance optimization of SSLBs.

Extreme fast charging of Ampere-hour (Ah)-scale electrochemical energy storage devices targeting charging times of less than 10 minutes are desired to increase widespread adoption. However, this metric is difficult to achieve in conventional Li-ion batteries due to their inherent reaction mechanism and safety hazards at high current densities. In this work, we report 1 Ah soft-package potassium-ion hybrid supercapacitors (PIHCs), which combine the merits of high-energy density of battery-type negative electrodes and high-power density of capacitor-type positive electrodes. The PIHC consists of a defect-rich, high specific surface area N-doped carbon nanotube-based positive electrode, MnO quantum dots inlaid spacing-expanded carbon nanotube-based negative electrode, carbonate-based non-aqueous electrolyte, and a binder- and current collector-free cell design. Through the optimization of the cell configuration, electrodes, and electrolyte, the full cells (1 Ah) exhibit a cell voltage up to 4.8 V, high full-cell level specific energy of 140 Wh kg −1 (based on the whole mass of device) with a full charge of 6 minutes. An 88% capacity retention after 200 cycles at 10 C (10 A) and a voltage retention of 99% at 25 ± 1 °C are also demonstrated.

Lithium-CO2 batteries (LCBs) are regarded as a promising energy system for CO2 drawdown and energy storage capability which has attracted widespread interest in carbon neutrality and sustainable societal development. However, their practical application has been limited by slow kinetics in catalytic reactions and poor reversibility of Li2CO3 products which leads to the issue of a large overpotential, low energy efficiency and poor reversibility. Herein, an efficient catalyst design and synthesis strategy is proposed to overcome the abovementioned bottleneck. Through an electrical joule heating procedure, Pt with random crystal orientations is converted into a 3D porous Pt catalyst with preferred (111) crystal orientation within seconds, exhibiting enhanced CO2 conversion kinetics with superior electrochemical performance. This includes ultralow overpotential (0.45 V), fast rate charging (up to 160 mu A cm-2) and high stability (over 200 cycles under 40 mu A cm-2). A proof-of-concept stacked Li-CO2 pouch cell, with stable operation under practical current density is demonstrated, indicating significant potential for large-scale operations. This bottom-up design of efficient catalysts and synthesis strategy offers a rapid and cost-effective approach to maximizing catalytic sites for CO2 conversion under restricted catalyst loading, showcasing its versatility across a broad spectrum of catalyst-based energy conversion and storage systems.

As the need for high-energy-density bat-teries continues to grow,lithium-sulfur(Li-S)batteries have become a highly promising next-generation energy solution due to their low cost and exceptional energy density compared to commercially available Li-ion bat-teries.Research into carbon-based sulfur hosts for Li-S batteries has been ongoing for over two decades,lead-ing to a significant number of publications and patents.However,the commercialization of Li-S batteries has yet to be realized.This can be attributed,in part,to the instability of the Li metal anode.However,even when considering just the cathode side,there is still no consen-sus on whether carbon-based hosts will prove to be the best sulfur hosts for the industrialization of Li-S batter-ies.Recently,there has been controversy surrounding the use of carbon-based materials as the ideal sulfur hosts for practical applications of Li-S batteries under high sulfur loading and lean electrolyte conditions.To address this question,it is important to review the results of research into carbon-based hosts,assess their strengths and weaknesses,and provide a clear perspective.This review systematically evaluates the merits and mechanisms of various strategies for developing carbon-based host materials for high sulfur loading and lean electrolyte conditions.The review covers structural design and functional optimization strategies in detail,providing a comprehensive understanding of the development of sulfur hosts.The review also describes the use of efficient machine learning methods for investigat-ing Li-S batteries.Finally,the outlook section lists and discusses current trends,challenges,and uncertainties surrounding carbon-based hosts,and concludes by presenting our standpoint and perspective on the subject.

Lithium-CO2 batteries (LCBs) are regarded as a promising energy system for CO2 drawdown and energy storage capability which has attracted widespread interest in carbon neutrality and sustainable societal development. However, their practical application has been limited by slow kinetics in catalytic reactions and poor reversibility of Li2CO3 products which leads to the issue of a large overpotential, low energy efficiency and poor reversibility. Herein, an efficient catalyst design and synthesis strategy is proposed to overcome the abovementioned bottleneck. Through an electrical joule heating procedure, Pt with random crystal orientations is converted into a 3D porous Pt catalyst with preferred (111) crystal orientation within seconds, exhibiting enhanced CO2 conversion kinetics with superior electrochemical performance. This includes ultralow overpotential (0.45 V), fast rate charging (up to 160 mu A cm-2) and high stability (over 200 cycles under 40 mu A cm-2). A proof-of-concept stacked Li-CO2 pouch cell, with stable operation under practical current density is demonstrated, indicating significant potential for large-scale operations. This bottom-up design of efficient catalysts and synthesis strategy offers a rapid and cost-effective approach to maximizing catalytic sites for CO2 conversion under restricted catalyst loading, showcasing its versatility across a broad spectrum of catalyst-based energy conversion and storage systems.

Lithium-CO2 batteries (LCBs) are regarded as a promising energy system for CO2 drawdown and energy storage capability which has attracted widespread interest in carbon neutrality and sustainable societal development. However, their practical application has been limited by slow kinetics in catalytic reactions and poor reversibility of Li2CO3 products which leads to the issue of a large overpotential, low energy efficiency and poor reversibility. Herein, an efficient catalyst design and synthesis strategy is proposed to overcome the abovementioned bottleneck. Through an electrical joule heating procedure, Pt with random crystal orientations is converted into a 3D porous Pt catalyst with preferred (111) crystal orientation within seconds, exhibiting enhanced CO2 conversion kinetics with superior electrochemical performance. This includes ultralow overpotential (0.45 V), fast rate charging (up to 160 mu A cm-2) and high stability (over 200 cycles under 40 mu A cm-2). A proof-of-concept stacked Li-CO2 pouch cell, with stable operation under practical current density is demonstrated, indicating significant potential for large-scale operations. This bottom-up design of efficient catalysts and synthesis strategy offers a rapid and cost-effective approach to maximizing catalytic sites for CO2 conversion under restricted catalyst loading, showcasing its versatility across a broad spectrum of catalyst-based energy conversion and storage systems.

Abstract Lithium‐ion batteries (LIBs) have been widely used in electric vehicles and energy storage industries. An understanding of the reaction processes and degradation mechanism in LIBs is crucial for optimizing their performance. In situ atomic force microscopy (AFM) as a surface‐sensitive tool has been applied in the real‐time monitoring of the interfacial processes within lithium batteries. Here, we reviewed the recent progress of the application of in situ AFM for battery characterizations, including LIBs, lithium–sulfur batteries, and lithium–oxygen batteries. We summarized advances in the in situ AFM for recording electrode/electrolyte interface, mechanical properties, morphological changes, and surface evolution. Future directions of in situ AFM for the development of lithium batteries were also discussed in this review.

Abstract Non-precious-metal catalysts possess promising potential to replace noble metals (e.g. Pt, Ru, Ir etc.) in broad catalytic areas; however the selection of efficient ones based on experimental results is extremely time-consuming and capital sensitive. Herein, we employ a computer-based method for virtual screening (VS) of chemical structures to discover new electrocatalysts via an efficient standard protocol. Specifically, we discovered a thermodynamically stable and highly active Cu-N2 Lewis acid site by combining molecular dynamics (MD) simulation, and density functional theory (DFT) calculations. The MD simulations rapidly screen out the structures that are both thermodynamically stable and stable in harsh electrolytes, while the DFT calculations filter out the ones with high overpotential by evaluating the adsorption energies for oxygen-related adsorption intermediates based on “Volcano plots” theory. The as-predicted Cu-N2 Lewis acid site was experimentally synthesized in a hollow nitrogen-doped octahedron carbon framework (Cu-N2@HNOC), in which an ultra-high loading of single Cu atoms (13.1 wt%, ICP-MS, the highest on record) is achieved. As a result, a flexible solid-state Zn-air battery was fabricated with Cu-N2@HNOC as the cathode catalyst that realized prolonged cycling, achieving a record high maximum power density of 78.1mW/cm2. Our strategy is widely applicable to seek valuable catalysts via VS for a wide range of applications, e.g. electrocatalysis, biocatalysis, and industrial catalysis, and suggests that the VS is more efficient than most experimental approaches.

Heterojunctions are a promising class of materials for high-efficiency bifunctional oxygen electrocatalysts in both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the conventional theories fail to explain why many catalysts behave differently in ORR and OER, despite a reversible path (* O2 ⇋* OOH⇋* O⇋* OH). This study proposes the electron-/hole-rich catalytic center theory (e/h-CCT) to supplement the existing theories, it suggests that the Fermi level of catalysts determines the direction of electron transfer, which affects the direction of the oxidation/reduction reaction, and the density of states (DOS) near the Fermi level determines the accessibility for injecting electrons and holes. Additionally, heterojunctions with different Fermi levels form electron-/hole-rich catalytic centers near the Fermi levels to promote ORR/OER, respectively. To verify the universality of the e/h-CCT theory, this study reveals the randomly synthesized heterostructural Fe3 N-FeN0.0324 (Fex N@PC with DFT calculations and electrochemical tests. The results show that the heterostructural F3 N-FeN0.0324 facilitates the catalytic activities for ORR and OER simultaneously by forming an internal electron-/hole-rich interface. The rechargeable ZABs with Fex N@PC cathode display a high open circuit potential of 1.504 V, high power density of 223.67 mW cm-2 , high specific capacity of 766.20 mAh g-1 at 5 mA cm-2 , and excellent stability for over 300 h.

Polyethylene oxide (PEO) based polymer electrolytes have been widely used in solid-state lithium batteries (SSBs) owing to the high solubility of lithium salt, favourable ionic conductivity, flexibility for improved interfacial contact and scalable processing. In this work, we summarize the main limitations remaining to be solved before the large-scale commercialization of PEO-based SSBs, including (1) improving ionic conductivity toward high-rate performance and lower operating temperature, (2) enhancing mechanical strength for improved lithium dendrite resistance and large-scale processing, (3) strengthening electrochemical stability to match high energy density electrodes with high voltage, and (4) achieving high thermal stability toward safe operation. Meanwhile, the characterization methods to investigate the ion transportation mechanism, lithium dendrite growth and decomposition reaction are also discussed.

Safety-related issues have always been one of the most critical barriers hindering the large-scale popularization of high-energy-density storage systems.

Silicon/carbon composite anode that combines high capacity and cycling stability has been successfully commercialized in lithium-ion battery (LIB) industry. Compared with the massive efforts devoted to optimizing the anode material structure or the electrolyte, less attention has been paid to the development of functional binders and their interaction with silicon/carbon material. As an essential component in the electrode, binders are expected to accommodate the repeated volume change of Si/C anode and maintain the electrode integrity as well as construct efficient electron/ion conductive network. In this review, recent advances in the functional polymers for silicon/carbon composite anode have been summarized from the perspective of intermolecular chemistry. The relationships between representative structure units (i.e. functional groups and chain structures) and performance of binders in Si/C anodes are discussed and we hope provide a fundamental perspective on performance optimization of Si/C anodes.

The oxygen reduction/evolution reactions play a paramount role in determining the performance of rechargeable metal-air batteries and fuel cells. Herein, we have successfully synthesized FeN-doped hierarchically porous carbon (FeN-HPC) materials with 3D honeycomb-like structure by NaCl-assisted pyrolysis method, which uses green and cheap glucose and dicyandiamide as organic precursors. Due to the extremely high percentage (93.7%) of graphitic-N & pyridinic-N in ultra-thin carbon nanosheets-assembled hierarchical structure with macro-meso-micro pores and large specific surface area, FeN-HPC exhibits excellent ORR activity, which surpasses commercial Pt/C manifested in higher half-wave potential (0.888 V vs. 0.845 V) and kinetic current density (23.2 mA cm(-2) vs. 3.6 mA cm(-2)@0.85 V). The primary zinc-air battery using FeN-HPC electrocatalyst exhibits a peak power density of 241 mW cm(-2) at a high current density of 344 mA cm(-2). Moreover, after coupling with non-precious NiFe-hydroxides nanosheets, the rechargeable Zn-air battery exhibits a narrow potential gap of 0.61 V between charging and discharging. Significantly, the battery exhibits excellent durability with a negligible decrease (0.76%) of discharging potential after 1000 cycles, demonstrating significantly better performance than that of Zn-air batteries previously reported. Our work provides a promising way for building highly efficient electrocatalyst and high performance rechargeable zinc-air batteries. (C) 2019 Elsevier Ltd. All rights reserved.

3D self-supported hierarchical Ni@NCNT/NiMoN shows remarkable activity, durability and anti-oxidation ability as the promising HER&OER electrode for storing electricity.

Water splitting is an efficient strategy to produce purity hydrogen and convert intermittent electricity from renewable wind and solar sources. In this work, dense NiMoO4 micropillars arrays (MPAs) were in-situ grown on nickel foam (NF) through facile hydrothermal method, then the NiMoO4/NF were converted into NiMoO4-P/NF and NiFe/NiMoO4/NF via phosphating and electrodeposition method, respectively. The NiMoO4-P/NF electrode required small overpotentials of 34 mV@10 mA cm(-2) and 130 mV@100 mA cm(-2) for hydrogen evolution reaction (HER). The NiFe/NiMoO4/NF electrode exhibited excellent oxygen evolution reaction (OER) activity with overpotentials of 210 mV@10 mA cm(-2) and 300 mV@100 mA cm(-2). The overall water splitting using the anode-cathode couple of NiFe/NiMoO4/NF parallel to NiMoO4-P/NF only consumes low voltages of 1.47 V@10 mA cm(-2) for 100 h and 1.66 V@100 mA cm(-2) for 50 h in 1 M KOH. The electronic modification and the well-designed hierarchical structure contribute the high energy-efficient and stabile overall water splitting. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Carbon materials play indispensable roles in energy-related systems, and constructing fast chargeable carbon anodes is still one of the most interesting and meaningful topics in energy storage and conversion fields. Selection of an appropriate structure and quantity of quantum dots can improve the rate performances. Here we report a unique molecular beam template approach to inlay MnO quantum dots (MnOQD) into walls of carbon hetero-nanotubes to form a brand-new composite (MnOQD@CHNTs) and investigate the influences of the inlaid quantum dots on the structures and the fast charging properties of carbon hetero-nanotubes. Plenty of tiny inlaid MnOQD in the walls of carbon nanotubes are proved to be capable of expanding the carbon layer spacing, decreasing the degree of order, forming heterojunctions with carbon, and altering the local electronic cloud density of carbon. Therefore, the capability of MnOQD@CHNTs for Li+/Na+ transfer and storage is greatly improved due to the quantum dot effect of MnO. As a result, the MnOQD@CHNTs exhibit excellent cycling and rate performances as both lithium-ion battery (LIB) and sodium-ion battery (SIB) anodes, e. g. fully charged in 28.3 s with a capacity of 392.8 mA h.g(-1) (similar to 125.6 C) in LIB (the best ever reported).

Lithium-sulfur (Li-S) batteries are promising for next-generation electrochemical energy storage due to their high energy density and low cost. Here, we introduce light-weight polar carbon selfdoping C3N4 nanosheets (C-CNN) as sulfur host for the fabrication of high performance Li-S batteries. The role of carbon doping in boosting the electrical conductivity of C-CNN is revealed by electrochemical impedance spectroscopy and electrical conductivity measurements. The strong chemical interactions between C-CNN and polysulfides are investigated by adsorption and post-mortem X-ray photoelectron spectroscopy analysis. Benefiting from the high surface area, enhanced electrical conductivity and high content of active N species (56.7 at%) in C-CNN, the strong chemical interactions between C-CNN and polysulfides can be fully exploited to minimize the shuttle effect and achieve long cycle life of Li-S batteries. As a result, the C-CNN/S cathode delivers a high specific capacity of 1050 mAhg(-1), good rate capability and excellent cycling stability with a low capacity decay of 0.07% per cycle at 1 C over 500 cycles, showing better performance than nitrogen-doped graphene. A performance comparison with the literature also shows that C-CNN is one of the most promising nitrogen-containing carbon materials for long cycle life Li-S batteries.