Journal of Power Sources最新文献

A template-directing methodology combined with post-activation methodology is developed to synthesize hierarchical porous carbon (HPC) with a unique nanocage-like morphology and exceptional structural integrity, utilizing light MgO nanocapsules as templates and coal pitch as precursor. The specific surface area and pore volume of HPC can be precisely adjusted by varying the mass ratio between the chemical activator and PC. This optimized pore structure significantly enhances the kinetics of electrolyte ion diffusion, which is a crucial point for the high-performance supercapacitors. The superior capacitive energy-storage behavior with respect to capacitance and rate capability (168 and 160 F g⁻¹ at 1 and 100 A g⁻¹) can be delivered by HPC electrode as compared to commercial activated carbon and pristine PC. The great compatibility to high gravimetric and areal capacitances (173 F g⁻¹ and 1391 mF cm⁻²) can still be achieved even at 8 mg cm⁻² for HPC electrode. Moreover, a full hybrid Li ion capacitor fabricated using HPC, delivers outstanding rate capability, excellent Ragone performance, and exceptional cyclability, establishing the potential of this material for advanced energy storage systems. The successful integration of template-directed synthesis with activation techniques presents a scalable approach to convert coal pitch into high-performance electrode materials.

Optimizing the pore structure of the cathode catalyst layer of proton exchange membrane fuel cells (PEMFC) is crucial for improving oxygen transport and overall cell performance. In this paper, the simulated annealing (SA) algorithm was improved to iteratively optimize the catalyst layer reconstruction model, improve the algorithm's computational efficiency, and construct a model with physical properties close to the pore structure of the actual catalyst layer. The phase exchange process during the computation is performed using an improved Different Phase Neighbors (DPN) algorithm, which prioritizes the nodes with significant phase differences for phase exchange and improves the efficiency of generating candidate solutions. The Hierarchical Annealing Strategy accelerated convergence, reducing computational complexity without compromising accuracy. Comparative analyses of pore size distributions and performance evaluations between the reconstructed models and the actual CL structures confirmed the model's effectiveness and accuracy.

Sodium layered oxides Na_xMO₂ (x ≤ 1 and M = transition metal) are of great interest for sodium-ion batteries due to their high energy density and cost-effectiveness. However, these materials, whether they are stoichiometric (Na/M ≈ 1 as in O3 NaMO₂) or not (Na/M ≈ 0.7 as in P3/P2 Na_xMO₂), have certain disadvantages, namely sensitivity to humidity or inadequate capacity, respectively. Herein, we propose an intermediate composition Na_0.85Ni_0.38Zn_0.04Mn_0.48Ti_0.1O₂ that we succeed to stabilize in either O3 or a nanoscale mixture of O3–P3 or O3–P2 phases as proven by X-ray diffraction and transmission electron microscopy, through complex synthesis approaches including quenching, slow cooling and annealing in different atmospheres (Ar, air, O₂ etc). We rationalize the stabilization of different phases and microstructure as a function of synthesis conditions and show how it influences the electrochemical performance. Through this study we identified a single phase O3 Na_0.85Ni_0.38Zn_0.04Mn_0.48Ti_0.1O₂ synthesized at 1000 °C in air, which exhibits a high capacity of ∼170 mAh/g and good moisture stability. Furthermore, thanks to the synthesis-structure- electrochemical performance relationship identified here, we believe that this study will provide a reliable basis for optimizing the synthesis for best performing sodium layered oxides for commercialization.

Polymer electrolytes (PEs) have been intensively studied in lithium-ion batteries and the studies have recently focused on improving their electrochemical performances. In this study, an in situ thermal curing method is proposed to prepare polyethylene glycol-based electrolytes using a cyclic phosphazene cross-linker directly onto the lithium anode, endowing the preparation of PEs with improved ion transport across the interfaces and better electrochemical performances than those using free-standing polymer electrolytes. The buildup of the cross-linked electrolyte network by incorporating the phosphazene cross-linker endows the as-prepared PEs exhibiting excellent deformation and thermal stability, a wide electrochemical window, high ionic conductivity (3.07 × 10⁻³ S cm⁻¹) at room temperature. The in situ-formed, cross-linked electrolyte network with good elasticity and conformal attachment at the electrolyte/electrode interface achieves a high capacity (>160 mAh g⁻¹ at 0.1C rate) and a long cycle life at room temperature (0.2C rate, 93.8% at 250 cycles) in the equipped Li|LiFePO₄ cell, making this strategy a promising approach for developing the next-generation lithium-ion batteries.

Prelithiation emerges as a promising strategy to compensate the irreversible initial capacity loss of the SiO/Graphite (SiO/Gr) composite anode. However, many scalable prelithiation methods encounter challenges of low efficiency and inhomogeneity, primarily stemming from a limited understanding of the spatial and temporal variations in prelithiation kinetics within large-scale electrodes. Utilizing an electrochemical prelithiation model, we integrated optimal electrode structure design with an electrochemically controllable method to concurrently enhance prelithiation efficiency and homogeneity. We demonstrated that prelithiation efficiency can be controlled by specifying the prelithiation current, while the design of the channel arrangement in the perforated electrode can enhance prelithiation homogeneity. Furthermore, we elucidated the interaction mechanism among channels under varying prelithiation currents and explored the impacts of channel size, channel spacing, and channel arrangement on prelithiation homogeneity under high prelithiation efficiency. With the insight gained from our simulation, the SiO/Gr composite anode featuring a channel diameter of 500 μm and a square channel arrangement with a spacing of 8.7 mm was designed. This design achieved a high prelithiation efficiency within 10 h, and maintained the prelithiation nonuniformity parameter below 0.1, accelerating the practical implementation of high-energy-density SiO/Gr composite anodes.

Interfacial side reaction is a major problem faced by solid state electrolyte (SSE), especially the oxidation reaction between high-voltage cathode materials and SSE. Herein, a double-layer PVCA-ETPTA|LAGP-PPC Janus solid electrolyte (JSE) with ultra-high interfacial stability is successfully designed. An oxidation tolerant cross-linked poly (Vinylene Carbonate) (PVCA)-Ethoxylated trimethylolpropane triacrylate (ETPTA) electrolyte is used on the cathode side, resulting in a stable interfacial layer under high-voltage. To enhance the stability of SSE|Li interface, a protective Li_1.5Al_0.5Ge_1.5P₃O₁₂ (LAGP)-Poly (propylene carbonate) (PPC) layer is adhered to Li metal. The obtained dual-layer structure shows great thermal stability with an electrochemical stable window of 0–4.5 V. Moreover, the PVCA-ETPTA layer fabricated by in-situ polymerization helps building an integrated structure, which can significantly reduce the interfacial resistance. The ionic conductivity of LP|PE can reach 1.2 × 10⁻⁴ S cm⁻¹ at 55 °C. As a consequence, the assembled NCM622|LP|PE|Li solid state cell shows exceptional electrochemical performance, with 70 % cycle retention for 100 cycles at 0.2 C.

Due to the commercialization of solid oxide cells (SOC) progressing at an accelerated pace, computationally inexpensive SOC models adapted to the iterative nature of the engineering process are in increasing demand. Flow simulation in the stack is especially challenging in this regard because detailed computational fluid mechanic models are computationally demanding, while simplified models rely on pressure loss coefficients and friction factors not readily available in the literature. In this study, a computationally inexpensive algebraic model of an SOC stack internal manifold is developed and calibrated for laminar flow conditions. Thereby, pressure loss coefficients and Darcy friction factors are determined for a broad range of operating conditions through symbolic regression of Navier–Stokes flow simulation results of stacks of 20 to 40 cells. The derived Darcy friction factors for the inlet and outlet manifolds prove to be of particular importance, as they deviate strongly from the expressions assumed in similar modeling studies. The predictive power of the developed model is demonstrated by providing accurate predictions of the flow distribution in the stack, even outside of the calibration window.

Potassium Metal Batteries (KMBs) are emerging as favorable candidates for next-generation high-efficiency energy storage technologies, due to their impressive specific capacity, low redox potential, and the abundance of K. Nevertheless, challenges such as dendrite growth and considerable volume expansion have been hindering in their commercial utilization. Herein, a lightweight and self-supporting flexible three-dimensional (3D) composite host with porous metal–organic frameworks and carbon-nanotube (CNT@ZIF-8) is developed. The unique design of CNT@ZIF-8 composite host offers a multitude of potassiophilic N/Zn active nuleation sites, extensive surface area, and a porous structure. These features play a pivotal role in the management of K transport dynamics, facilitating K⁺ prestoring and predistribution. Benefiting from the narrowed concentration polarization and uniform nucleation, a dendrite-free K metal anode is constructed. The K@CNT@ZIF-8 anode demonstrates a remarkable durability, operating for 3200 h under 0.35 mA cm⁻² and 0.35 mAh·cm⁻² conditions, while also maintaining stability over 650 h at 1.0 mA cm⁻² and 1.0 mAh·cm⁻². Additionally, the full cell of PTCDA||K@CNT@ZIF-8 variant exhibits a boosted cycling stability (88 mAh g⁻¹ at 5 C after 1000 cycles) and rate performance (98 mAh g⁻¹ at 20 C). The results underscore the immense potential of CNT@ZIF-8 in facilitating practical applications for energy storage.

Open-framework crystal structured vanadates have been extensively investigated as cathode materials for aqueous zinc-ion batteries (ZIBs). However, the inherent challenges of poor electronic conductivity and structural instability compromise the rate capability and overall cycle life. Herein, we first successfully synthesized octahedral MIL-101(V) and prepared the Zn₃(OH)₂V₂O₇·2H₂O@C (ZVOH@C) composite by in-situ electrochemical conversion of MIL-101(V)-derived crystalline V₂O₃ and carbon composite (V₂O₃@C). The ZVOH@C composite of open-framework crystal structured Zn₃(OH)₂V₂O₇·2H₂O and conductive carbon skeleton not only possesses more active sites, more stable crystal structure and higher electrical conductivity, but also provides faster Zn²⁺ diffusion kinetics. As expected, the ZVOH@C composite electrode exhibits excellent capacity of 506.3 mAh/g at a current density of 1.0 A/g, exceptional rate performance (375.7 mAh/g at 20.0 A/g), and impressive long-term cycling stability, maintaining 314.5 mAh/g over 5000 cycles at 20.0 A/g. This study demonstrates a promising method for designing new cathode materials through in-situ electrochemical synthesis for ZIBs.