Energy advances最新文献

[This corrects the article DOI: 10.1039/D4YA00043A.].

Among the diverse range of modern renewable energy storage technologies, electrochemical energy storage devices have been rapidly adopted across various applications owing to their superior characteristics, including high coulombic efficiency, elevated energy and power densities, scalability, modularity, and rapid response capabilities. Conjugated conducting polymers have recently attracted significant attention in electrochemical energy storage devices due to their unique pseudocapacitive behavior, hybrid ionic/electronic conduction, rapid doping/de-doping dynamics, bulk intercalation of ionic species, high specific capacity, and exceptional structural and thermal stability. Conducting polymers exhibit pseudocapacitance through reversible redox reactions coupled with doping/de-doping processes, facilitating the movement of counterion dopants and ionic species between the polymer matrix and the electrolyte. The size and nature of counterion dopants significantly influence the electrochemical performance of these polymers. Small counterion dopants like chloride enhance redox exchange with the electrolyte and broaden the electrochemical potential window, which is advantageous for electrochemical energy storage devices. The pseudocapacitive properties can be further enhanced by increasing the semi-crystalline characteristics and attaining longer polymer chains. This review article focuses on the fabrication methods, fundamental aspects of ionic and electrical conductivity, and pseudocapacitance characteristics of conjugated conducting polymers, as well as their applications in Li–ion batteries, supercapacitors, and redox flow batteries.

Polyethylene oxide (PEO)-based solid composite electrolytes (SCEs), with inorganic fillers, are studied extensively due to their effective balance between mechanical and electrochemical properties. The correlation between the composition of SCEs and their electrochemical behavior has been studied extensively, primarily focusing on the type of polymer matrix with a bias towards high lithium (Li) salt. In this study, we examine the changes in the properties of SCEs at two low EO : Li ratios, 43 : 1 and 18 : 1, in the PEO-LiTFSI matrix (with and without 10 wt% of 5 μm LLZTO) and evaluate their impact on Li stripping and plating reactions. Although higher salt concentration (18 : 1) results in substantially higher ionic conductivity (by approximately an order of magnitude), interestingly we observe that lower salt concentration (43 : 1) exhibits up to 3 times longer Li cycling life. Notably, electrolytes with low salt concentration (43 : 1) are much stiffer, with compressive modulus more than twice as high as the 18 : 1 counterpart. Although the ionic conductivity of the electrolyte is often the most immediate concern in the electrolyte design process, these findings accentuate the equal importance of mechanical properties in order to ensure successful electrolyte performance throughout prolonged Li cycling.

Developing low cost and highly efficient electrocatalysts for the oxygen evolution reaction (OER) is highly desired for renewable energy production. Ni-based electrocatalysts have been widely investigated as candidates for the OER, but developing a low-cost, easily synthesized electrocatalyst with high activity and good stability remains elusive. Herein, we report the facile electrodeposition of triethanolamine-decorated Ni oxide on carbon paper (Ni/CP-TEA) as an efficient electrocatalyst for water oxidation. Structural and experimental analyses reveal that the electrode surface is modified by triethanolamine (TEA) through Ni–N coordination bonding. The leaching of TEA drives rapid in situ surface reconstruction, facilitating the generation of high-valence Ni (Ni³⁺) species, thereby accelerating the OER performance. The Ni/CP-TEA exhibits enhanced electrocatalytic OER performance with a low overpotential of 320 mV at 10 mA cm⁻² and good long-term stability. This work presents a simple route for the rational design of cost-effective and highly efficient OER catalysts.

In many cases, batteries used in light e-mobility vehicles such as e-bikes and e-scooters do not have an active thermal management system. This poses a challenge when these batteries are stored in sub-zero temperatures and need to be charged. In such cases, it becomes necessary to move the batteries to a warmer location and allow them to acclimatize before charging. However, this is not always feasible, especially for batteries installed permanently in vehicles. In this work, we present an internal high-frequency AC heater for a 48 V battery, which is used for light electric vehicles of EU vehicle classes L1e and L3e-A1 for a power supply of up to 11 kW. We have taken advantage of the features of a damped oscillating circuit to improve the performance of the heater. Additionally, only a small inductor was added to the main current path through a cable with three windings. Furthermore, as the power electronics of the heater is part of the battery main switch, fewer additional parts inside the battery are required and therefore a cost and space reduction compared to other heaters is possible. For the chosen setup we reached a heating rate of up to 2.13 K min⁻¹ and it was possible to raise the battery temperature from −10 °C to 10 °C using only 3.1% of its own usable capacity.

Multivalent-ion and all-solid-state batteries have emerged as potential solutions to address resource concerns and safety issues. Calcium is a promising element for multivalent-ion batteries owing to its abundance in the Earth's crust and low reduction potential. In addition, complex hydrides exhibit both high ion conductivity and reduction stability, making them suitable materials for solid-state ion conductors. In this study, we investigated the thermal stability and optimised the synthesis conditions of calcium monocarborane, namely, Ca(CB₁₁H₁₂)₂, which is a closo-type calcium complex hydride. In addition, we conducted electrochemical analysis to assess its performance as a solid-state divalent-ion conductor. The results indicate that a heat-treatment temperature of 433 K provides Ca(CB₁₁H₁₂)₂ with higher ion conductivity (σ = 1.42 × 10⁻⁴ S cm⁻¹) than the other heating temperatures. Thus, 433 K is considered optimal because [CB₁₁H₁₂]⁻ anions decompose when heat-treated at and above 453 K. Furthermore, the insertion and deinsertion of Ca²⁺ ions are stable and reversible in symmetric cells employing Ca–Sn alloy electrodes, representing the first time this has been observed for an inorganic solid-state calcium-ion conductor. Such insertion and deinsertion highlight the potential of Ca(CB₁₁H₁₂)₂ as a solid-state electrolyte for battery applications.

The electrochemical conversion of CO₂ into C₁ and C₂ hydrocarbons, such as methane and ethylene, is a promising pathway toward achieving net zero carbon emissions; however, owing to the high activation barrier of CO₂, this reaction remains a big challenge. In this work, an effective strategy has been developed through the synthesis of a low-cost vanadium- and copper-based layered double hydroxide (LDH) decorated with TiO₂ nanoparticles (VCu LDH/TiO₂) as a highly efficient electrocatalyst for the electrochemical reduction of CO₂ to ethylene. Structural and morphological studies of the developed electrocatalyst were carried out using various analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (FESEM), X-ray photoelectron microscopy (XPS) and transmission electron microscopy (TEM), which confirmed the successful formation of VCu LDH/TiO₂. The electrochemical CO₂ reduction reaction (CO₂RR) was performed in 0.1 M KHCO₃ using an H-type cell and afforded CO, H₂, CH₄, and C₂H₄ as value-added end products. The highest faradaic efficiency of 84% was obtained for C₂H₄ at −0.4 V vs. RHE. The above results suggest that the VCu LDH/TiO₂ NP electrocatalyst may be an excellent candidate for CO₂ reduction and can also be utilized in a wide range of energy conversion and storage applications.

Rationally designing high-efficiency catalysts for electrochemical two-electron water oxidation reaction (2e⁻ WOR) to produce hydrogen peroxide (H₂O₂) is extremely important, while designing bimetallic metal–organic frameworks (MOFs) is of great significance for effective 2e⁻ WOR. Herein, MIL-53(Fe) and different proportions of Co-doped MIL-53(Fe) were prepared by a hydrothermal method. The structural characterization and elemental analysis showed that the Co ions were successfully doped into MIL-53(Fe) to form a MIL-53(Fe/Co) bimetallic MOF, and the morphology of MIL-53(Fe/Co) became more regular after Co doping. We found that the optimized MIL-53(Fe/Co) exhibits remarkable 2e⁻ WOR performance, which gave an overpotential of 150 mV at 1 mA cm⁻². The overpotential of MIL-53(Fe/Co) was approximately 220 mV (at 1 mA cm⁻²) lower than that of MIL-53(Fe), which may be attributed to the change of microstructure of MIL-53(Fe) after Co doping and the synergistic effect between Fe/Co. Our work introduces a strategy for designing bimetallic MOF-based electrocatalysts, opening up new possibilities for efficient 2e⁻ WOR systems.

A unique feature of redox flow batteries (RFBs) is that their open circuit voltage (OCV) depends strongly on the state of charge (SOC). In the present work, this relation is investigated experimentally for the all-vanadium RFB (AVRFB), which uses vanadium ions of different oxidation states as redox pairs in both half-cells. In contrast to several literature studies, which use OCV measurements to deduce the SOC via the Nernst equation, we propose a method based on UV-Vis spectroscopy for SOC estimation, thereby enabling completely independent SOC and OCV measurements. Moreover, rather than relying on data at a single wavelength this UV-Vis method uses the entire absorption spectrum to obtain more robust values for the SOC. The obtained SOC-OCV data agree reasonably well with literature values and reveal a significant influence of the thermodynamic non-ideality of the solutions on the OCV as described by the Nernst equation.

Zeolite-templated carbons (ZTCs) are widely studied from basic research to applied research owing to their characteristic pore structures. To synthesize ZTCs, molecules with a size smaller than the pore sizes of template zeolites have been used as carbon sources for their carbonization in the zeolite pores. Therefore, the type of carbon sources has been limited to molecules with a size smaller than the pore sizes of zeolites. In this study, highly structurally regular N-doped zeolite-templated carbons are synthesized using propylene as a carbon source and chitin as both carbon and nitrogen sources via a depolymerized oligomer filling (DOF) mechanism. Chitin, the second most abundant biopolymer on the Earth, consists of N-acetylglucosamine (GlcNAc) as its unit structure and has a much larger size than the zeolite pores. NaY zeolite is used as a template without drying and mixed with chitin. The mixture is subjected to chemical vapor deposition (CVD) using propylene and subsequent heat treatment for graphitization, followed by HF etching for zeolite removal. Upon heating the mixture of the zeolite and chitin, chitin is catalytically depolymerized into chitin oligosaccharide radicals by the zeolite, and the radicals are absorbed into the zeolite pores below 450 °C, which is supported by electron spin resonance and N₂ adsorption/desorption analyses. The ZTC structure is completed by propylene CVD for adequately filling carbon into the zeolite pores. A validation experiment is conducted using GlcNAc instead of chitin to confirm that the N-doped ZTC is synthesized via the DOF mechanism. The resulting N-doped ZTCs have high structural regularity and high surface areas ranging from 3420 to 3740 m² g⁻¹, and show a higher area-normalized capacitance than undoped ZTC as electric double-layer capacitor electrodes. Utilizing chitin from crustacean shells as one of the raw materials highlights an innovative approach to waste reduction and advances sustainable materials science, contributing to the circular economy and sustainable development goals.