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This review discusses the coking process in SOFCs, carbon detection methods, and strategies to inhibit coking of the anode with a primary focus on alternative anode materials. We also present future research directions in hydrocarbon-fueled SOFCs.

Platinum-based catalysts are regarded as the Holy Grail of hydrogen evolution reaction (HER). As a benchmark catalyst for HER, the commercial Pt/C catalyst has low Pt utilization efficiency and high cost, which hinders its commercialization. Atomic clusters-based catalysts show high efficiency of atom utilization and high performance toward electrocatalysis. Herein, an environmentally friendly preparation strategy is proposed to construct Pt atomic clusters on the polyoxometalates-carbon black (Pt-POMs-CB) support. Density functional theory (DFT) calculations reveal that the Pt clusters can be stably anchored on the surface with the driving force arising from the charge transfer from Pt atoms to O atoms of the POMs. Benefiting from metal-support interaction, Pt atomic clusters embedded in silicotungstic acid-carbon black (Pt-STA-CB) exhibit excellent HER activity with an overpotential of 33.8 mV at 10 mA cm

Rechargeable all-solid-state batteries (ASSBs) are considered to be the next generation of devices for electrochemical energy storage. The development of solid-state electrolytes (SSEs) is one of the most crucial subjects in the field of energy storage chemistry. The newly emerging halide SSEs have recently been intensively studied for application in ASSBs due to their favorable combination of high ionic conductivity, exceptional chemical and electrochemical stability, and superior mechanical deformability. In this review, a critical overview of the development, synthesis, chemical stability and remaining challenges of halide SSEs is given. The design strategies for optimizing the ionic conductivity of halide SSEs, such as element substitution and crystal structure design, are summarized in detail. Moreover, the associated chemical stability issues in terms of solvent compatibility, humid air stability and corresponding degradation mechanisms are discussed. In particular, advanced in situ/operando characterization techniques applied to halide-based ASSBs are highlighted. In addition, a comprehensive understanding of the interface issues, cost issues, and scalable processing challenges faced by halide-based ASSBs for practical application is provided. Finally, future perspectives on how to design high-performance electrode/electrolyte materials are given, which are instructive for guiding the development of halide-based ASSBs for energy conversion and storage. Graphical Abstract In this review, a critical overview is given on the development, synthesis, chemical stability and remaining challenges facing for halide SSEs. The design strategies for optimizing ionic conductivity of halide SSEs like elements substitution, crystal structures design are summarized in detail. Future perspectives are given on how to design high-performance electrode/electrolyte materials.

With the merits of high energy density, light weight, and low electrode potential, lithium metal anodes (LMAs) have lately sparked worldwide attention in the field of batteries. However, their low Coulombic efficiency, tremendous volume expansion, and serious dendrite growth make lithium metal batteries (LMBs) unsuitable for a wide variety of applications. Moreover, when lithium dendrite crosses the electrolyte and reaches the cathode material, it may cause short circuit and safety issues for batteries. Herein, to accelerate the development of LMBs, we give a brief summary of the dendrite growth mechanisms in both liquid and solid systems of electrolytes. In particular, various modification approaches to dendrite-free lithium metal batteries are discussed. Furthermore, advanced

A durable composite electrolyte membrane was prepared by rationally utilizing oxygen vacancies in flower-like CeO2 microspheres. The assembled solid-state lithium–oxygen battery with this composite electrolyte shows remarkable cyclability.

The limit of the energy density and increasing security issues on sodium-ion batteries (SIBs) impede their further development. Solid-state sodium metal batteries are potential candidates to replace the present SIBs. However, low ionic conductivity and poor interface contact hinder their progress. In this work, the impact of Al doping on the crystalline structure and ionic transport in Na3.4Zr2(Si0.8P0.2O4)3 was studied by neutron powder diffraction. The ionic conductivity of Na3.5Zr1.9Al0.1Si2.4P0.6O12 achieves 4.43 × 10-3 S cm-1 at 50 °C. The polarization voltage of the Na||Na symmetric battery is about 40 mV after cycling for more than 1600 h. Moreover, a solid-state sodium-sulfur battery with a monolithic structure was constructed to alleviate the interfacial resistance problems. Its specific discharge capacity can still keep 300 mA h g-1 after 480 cycles at 300 mA g-1. The work provides a promising strategy to design solid-state sodium-sulfur batteries with high performances.

Solid-state electrolytes (SSEs) are expected to replace liquid electrolytes in lithium metal batteries (LMBs) with good safety and mechanical strength. However, the existing problems of the Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte, like its poor contact with electrodes, serious side reactions and low ionic conductivity, limit its practical application. In this work, a chlorine (Cl)-doped LATP electrolyte showing a high ionic conductivity of 0.423 mS cm−1 was successfully synthesized. Neutron powder diffraction (NPD) results reveal that the change of the Li+ coordination environment after Cl doping has an effect on the ion diffusion path in the bulk LATP. The fabricated Li symmetric battery with the Cl-doped LATP exhibits long-term compatibility and electrochemical stability against the lithium metal anode. The enhanced performance may be attributed to the in situ formed stable solid electrolyte interphase (SEI) layer. Meanwhile, compared to the LATP electrolyte, the Li|LiFePO4 (LFP) full battery with Cl-doped LATP as an electrolyte has an improved rate performance and cycling performance. This work demonstrates that Cl doping may be an effective approach for improving the performance of the LATP electrolyte.

Solid-state lithium-ion batteries have attracted great attention in recent years due to their remarkable safety and high energy density. However, the ionic conductivities of most solid-state electrolytes (SSE) are still not high enough for practical applications. Herein, we report a high-performance quasi-solid-state electrolyte composed of an electrospinning LATP-PVDF-HFP nanofiber matrix and an in situ formed gel. The prepared quasi-solid gel electrolyte shows a 3D porous network with significantly improved ionic conductivity up to 3.394 mS cm−1. Meanwhile, the quasi-solid-state electrolyte exhibits a wider electrochemical window than the gel electrolyte, due to the synergistic effect between the 3D network fiber and in situ formed gel. The Li|CGE|LiFePO4 battery with this quasi-solid gel electrolyte shows good rate capability and cycling stability, and the discharge capacity of the cell is 146.6 mA h g−1 at 2C. The capacity retention can still reach 97% after 300 cycles at 0.5C. This work provides a promising strategy for designing high-performance lithium metal batteries.

For the application of sodium batteries, one challenge is the irregular deposition and dendrite growth during the cycling process. Herein, we report that spontaneous alloying reactions can occur by...

Sodium batteries have attracted much attention owing to their abundant reserves and low cost of Na raw materials and diverse sources of electrode materials. However, even if no external factors are applied, sodium batteries might fail in a certain probability during the normal operation, which exhibits the failure modes of electrochemical performance decay and the component destruction of the batteries, resulting in these failure consequences such as battery thermal runaway, short circuit, fire etc. In this paper, various failure causes are analyzed for the components of sodium batteries like cathodes, anodes, electrolytes, separators, current collectors and the case of the sodium battery, according to the theoretical failure chain model of failure mode and effect analysis (FMEA) technology. Progress of sodium battery failure research is summarized based on above sodium battery components. Moreover, the failure analysis process of sodium batteries is also proposed. The sodium battery failure analysis system is finally proposed. It will provide the informations for the failure research, safe use, design and manufacture of sodium batteries.

In order to satisfy the increasing requirements on operation time of wearable and portable electronic devices, novel self-powered systems by integrating triboelectric nanogenerator (TENG) with an energy storage device have emerged as a promising technology to provide sustainable power. Here, a flexible sodium composite anode (Na@CC) was prepared by infusing the molten sodium into flexible sodiophilic carbon cloth. The symmetric cell with the Na@CC anode shows stable sodium plating and stripping for 400 h. The full cell with a flexible quasi-solid-state electrolyte, Na

Solid-state lithium metal batteries (SSLMBs) are an emerging technology because they can effectively solve the safety problem facing the lithium-ion batteries with nonaqueous liquid electrolyte. However, the lithium dendrite problem in SSLMBs can still occur at the sites of grain boundaries and defects. It is reported that effective charge procedures enable to suppress the growth of lithium dendrite, especially the pulse charging mode. In this work, SSLMBs were charged by a vertical contact-separation triboelectric nanogenerator (TENG). The effects of the pulse current on the lithium dendrite growth of SSLMBs are studied. It is found that the lithium ions can diffuse uniformly during the intermittent period of the pulse current compared to the constant current charge, so the growth rate of the lithium dendrites is effectively inhibited by the pulse current. At the same time, it is found that the lower the frequency of TENG is, the slower the growth rate of lithium dendrites is. This work provides a guideline for designing an appropriate charging method for durable SSLMBs.

Lithium-ion batteries (LIBs) have been widely used in portable electronic devices and electrical vehicles. However, the LIBs with flammable organic liquid electrolytes have safety issues. Solid electrolytes have many advantages compared with organic liquid electrolytes, especially in terms of their low flammability and wide operation temperatures. In particular, the composite polymer electrolytes combining the advantages of the polymer and the inorganic electrolytes have good interfacial contact and high ionic conductivity. In this work, the composite electrolyte membranes consisting of a polyacrylonitrile (PAN)-Li6.5La3Zr1.5Ta0.5O12 (LLZTO) matrix as well as LiClO4 and Mg(ClO4)2 dual salts have been prepared by electrospinning. It is found that the cycle stability of the battery can be greatly improved by adding magnesium salt to the electrolyte membrane. The magnesium salt promotes the decomposition of LiPF6 in the electrolyte to produce fluoride ions. Thus, a stable protective layer of magnesium fluoride is formed on the surface of the lithium anode, which can effectively inhibit the growth of lithium dendrites, reduce the interface impedance, and increase the cycle life of the battery. Furthermore, the prepared lithium metal battery is also used to store mechanical energy harvested by triboelectric nanogenerators (TENGs).

Piezoelectric effect has been widely used in the photocatalytic and photoelectrochemical fields due to its unique property of modulating the energy bands of piezoelectric materials. In this work, we demonstrated that the piezoelectric effect can also be employed in the oxygen evolution reaction (OER) using non-centrosymmetric structured MoS2 nanosheets loaded with Au nanoparticles. Piezoelectric force microscopy (PFM) measurement reveals a piezoelectric response of the Au–MoS2 nanosheets. The prepared Au nanoparticle-loaded MoS2 nanosheet catalyst shows an enhanced OER performance under ultrasonic vibration, which is ascribed to the piezo-enhanced electrocatalytic effect. In addition, the proposed catalyst exhibits a piezo-catalytic effect in dye decomposition reactions. This study paves a way to design highly active catalysts for energy and environmental applications.

Solid state Na-CO2 batteries are a kind of promising energy storage system, which can use excess CO2 for electrochemical energy storage. They not only have high theoretical energy densities, but also feature a high safety level of solid-state batteries and low cost owing to abundant sodium metal resources. Although many efforts have been made, the practical application of Na-CO2 battery technology is still hampered by some crucial challenges, including short cycle life, high charging potential, poor rate performance and lower specific full discharge capacity. This paper systematically reviews the recent research advances in Na-CO2 batteries in terms of understanding the mechanism of CO2 reduction, carbonate formation and decomposition reaction, design strategies of cathode electrocatalysts, solid electrolytes and their interface design. In addition, the application of advanced in situ characterization techniques and theoretical calculation of metal–CO2 batteries are briefly introduced, and the combination of theory and experiment in the research of battery materials is discussed as well. Finally, the opportunities and key challenges of solid-state Na-CO2 electrochemical systems in the carbon-neutral era are presented.

Sodium-metal batteries with conventional organic liquid electrolytes have disadvantages including dendrite deposition and safety concern. In this work, we report a low-flammable electrolyte (NaPF6-...

The rational design of efficient and durable oxygen evolution reaction (OER) is important for energy conversion and storage devices. Here, we develop a two-step calcination method to prepare cobalt nanoparticles uniformly dispersed on perovskite oxide nanofibers and to tune oxygen vacancies in perovskite LaMn0.75Co0.25O3-δ nanofibers. The obtained product shows enhanced activity toward OER. In particular, the oxygen deficient LMCO-2 catalyst prepared by a two-step calcination shows excellent OER performance that is 27.5 times that of the LMO catalyst and is comparable to that of the commercial RuO2 catalyst. It also demonstates good stability because of its novel structure, abundant oxygen vacancies, and larger number of metal ions with a high oxidation state. As an air electrode for a flexible zinc-air battery, the cell with the LMCO-2 catalyst delivers a higher power density of 35 mW cm-2 and excellent cycling stability for 70 h. Moreover, the cell exhibits excellent flexibility under different bending conditions.

Understanding the carbon formation mechanism is critical for designing catalysts in various applications. Here, we report the observation of the carbon formation mechanism on Ni-based catalysts by environmental transmission electron microscopy (ETEM) over a wide temperature range in combination with molecular dynamics simulations and density functional theory calculations. In situ TEM observation performed in a C2H2/H2 atmosphere provides real-time evidence that Ni3C is an intermediate phase that decomposes to graphitic carbon and metallic Ni, leading to carbon formation. Mechanisms of acetylene decomposition and evolution of carbon atom configuration are revealed by molecular dynamics simulations, which corroborate the experimental results. The modification of MgO on NiO can effectively decrease the formation of graphitic layers and thus enhance the catalytic performance of NiO. This finding may provide an insight into the origin of the carbon deposition and aid in developing effective approaches to mitigate it.

The design and synthesis of efficient and cost-effective electrocatalysts are vital for rechargeable zinc–air batteries (ZABs). Here, nitrogen-doped NiCo2O4 (N-doped NiCo2O4) was prepared and used ...

Developing low-polarization and stable cathodes is key to the success of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Here we report a study on the electrochemical performance and stability of a commercial (La0.60Sr0.40)0.95(Co0.20Fe0.80)O3-δ (LSCF) cathode overcoated by a SrCo0.9Nb0.1O3-δ (SCN10) nanoscaled layer. At the optimal 20 wt% loading, the SCN10-LSCF bilayer cathode exhibits an 89.4% reduction in polarization resistance over the pristine LSCF at 650 °C. Over a 6,000-h testing at 650 °C, the SCN10-LSCF bilayer cathode also shows a similar stability to but much lower resistance than the pristine LSCF. A combined microscopic and spectroscopic post-test analysis unveils that SCN10-overcoat remains nanosized, well crystallized and uniformly distributed. An elongated, sporadically distributed phase was found and identified as SrCO3 in the SCN10 layer, which may contribute to the degradation of SCN10-LSCF cathode.

The development of high‐performance and low‐cost bifunctional electrocatalysts is still challenging for solving current energy and environmental problems. However, most electrocatalysts require complex synthesis processes, which prohibit mass production. Herein, NiCoFeP nanofibers are synthesized by phosphating the electrospun Ni,Co precursor nanofibers and subsequent displacement reaction of Ni and Fe3+ via impregnation of Fe(NO3)3 solution. The obtained NiCoFeP nanofibers catalyst possesses high intrinsic activity, abundant active sites, and superior kinetics, which shows excellent oxygen evolution reaction (OER) performance with low overpotential of 0.309 V at 50 mA cm−2 in 1 m KOH solution. It also exhibits a long‐term cycling performance for 200 h at 10 mA cm−2 as the cathode for zinc–air battery. Furthermore, it is demonstrated that this displacement reaction method is also suitable for preparing other catalysts NiMnP and NiCuP to enhance their OER performance. This work presents a novel approach for the fabrication of multimetallic catalysts for electrocatalysis.

Lithium metal is considered as the ideal anode for next-generation rechargeable batteries due to its highest theoretical specific capacity and lowest electrochemical potential. However, lithium dendrite growth during lithium deposition could lead to a short circuit and even cause severe safety issues. Here, we use solid-state electrolyte Li3InCl6 as an additive in nonaqueous electrolytes because of its high ionic conductivity (10-3 to 10-4 S cm-1) and good electrochemical stability. It is found that Li3InCl6 can in situ react with metallic lithium to form a ternary composite solid electrolyte interphase (SEI) consisting of a Li-In alloy, LiCl, and codeposited Li3InCl6. The composite SEI can effectively suppress Li dendrite growth and thereby maintain stable long-term cycling performance in lithium metal batteries. The protected lithium electrode exhibits stable cycling performance in a symmetric Li|Li battery for nearly 1000 h at a current density of 1 mA cm-2. Besides, the full battery with a LiFePO4 cathode and a metallic lithium anode delivers a stable capacity of 140.6 mA h g-1 for 500 cycles with a capacity retention of 95%. The Li|S battery with Li3InCl6-added LiTFSI in 1,3-dioxolane/1,2-dimethoxyethane electrolyte also shows significant improvement in capacity retention at 0.5 C. This work demonstrates an effective approach to design dendrite-free metal anodes.

Driver&rsquo, s driving actions on pedals can be regarded as an expression of driver&rsquo, s acceleration/deceleration intention. Quickly and accurately detecting driving action intensity on pedals can have great contributions in preventing road traffic accidents and managing the energy consumption. In this paper, we report a pressure-sensitive and self-powered material named triboelectric nano-generators (TENGs). The generated voltage data of TENGs, which is associated with the pedal action, can be collected easily and stored sequentially. According to the characteristics of the voltage data, we have employed a hybrid machine learning method. After collecting signals from TENGs and driving simulator simultaneously, an unsupervised Gaussian mixture model is used to cluster the pedal events automatically using data from simulator. Then, multi-feature candidates of the voltage data from TENGs are extracted and ranked. A supervised random forest model that treats voltage data of TENGs as input data is trained and tested. Results show that data from TENGs can have a high accuracy of more than 90% using the random forest algorithm. The evaluating results demonstrate the accuracy of the proposed data-driven hybrid learning algorithm for recognition of driver&rsquo, s pedal action intensity. Furthermore, technical and economic characteristics of TENGs and some common sensors are compared and discussed. This work may demonstrate the feasibility of using these data-driven methods on the detection of driver&rsquo, s pedal action intensity.