Alkaline water electrolysis (AWE) is the most mature technology for hydrogen production by water electrolysis. Alkaline water electrolyzer consists of multiple electrolysis cells, and a single cell consists of a diaphragm, electrodes, bipolar plates and end plates, etc. The existing industrial bipolar plate channel is concave-convex structure, which is manufactured by complicated and high-cost mold punching. This structure still results in uneven electrolyte flow and low current density in the electrolytic cell, further increasing in energy consumption and cost of AWE. Thereby, in this article, the electrochemical and flow model is firstly constructed, based on the existing industrial concave and convex flow channel structure of bipolar plate, to study the current density, electrolyte flow and bubble distribution in the electrolysis cell. The reliability of the model was verified by comparison with experimental data in literature. Among which, the electrochemical current density affects the bubble yield, on the other hand, the generated bubbles cover the electrode surface, affecting the active specific surface area and ohmic resistance, which in turn affects the electrochemical reaction. The result indicates that the flow velocity near the bottom of the concave ball approaches zero, while the flow velocity on the convex ball surface is significantly higher. Additionally, vortices are observed within the flow channel structure, leading to an uneven distribution of electrolyte. Next, modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures, namely, concave and convex, rhombus, wedge and expanded mesh, in the bipolar plate of alkaline water electrolyzer. The results show that the expanded mesh channel structure has the largest current density of 3330 A/m² and electrolyte flow velocity of 0.507 m/s in the electrolytic cell. Under the same current density, the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption. This work provides a useful guide for the comprehensive understanding and optimization of channel structures, and a theoretical basis for the design of large-scale electrolyzer.

The aging characteristics of lithium-ion battery (LIB) under fast charging is investigated based on an electrochemical-thermal-mechanical (ETM) coupling model. Firstly, the ETM coupling model is established by COMSOL Multiphysics. Subsequently, a long cycle test was conducted to explore the aging characteristics of LIB. Specifically, the effects of charging (C) rate and cycle number on battery aging are analyzed in terms of nonuniform distribution of solid electrolyte interface (SEI), SEI formation, thermal stability and stress characteristics. The results indicate that the increases in C rate and cycling led to an increase in the degree of nonuniform distribution of SEI, and thus a consequent increase in the capacity loss due to the SEI formation. Meanwhile, the increases in C rate and cycle number also led to an increase in the heat generation and a decrease in the heat dissipation rate of the battery, respectively, which result in a decrease in the thermal stability of the electrode materials. In addition, the von Mises stress of the positive electrode material is higher than that of the negative electrode material as the cycling proceeds, with the positive electrode material exhibiting tensile deformation and the negative electrode material exhibiting compressive deformation. The available lithium ion concentration of the positive electrode is lower than that of the negative electrode, proving that the tensile-type fracture occurring in the positive material under long cycling dominated the capacity loss process. The aforementioned studies are helpful for researchers to further explore the aging behavior of LIB under fast charging and take corresponding preventive measures.

Designing highly efficient Pt-free electrocatalysts with low overpotential for an alkaline hydrogen evolution reaction (HER) remains a significant challenge. Here, a novel and efficient cobalt (Co), ruthenium (Ru) bimetallic electrocatalyst composed of CoRu nanoalloy decorated on the N-doped carbon nanotubes (CoRu@N-CNTs), was prepared by reacting fullerenol with melamine via hydrothermal treatment and followed by pyrolysis. Benefiting from the electronic communication between Co and Ru sites, the as-obtained CoRu@N-CNTs catalyst exhibited superior electrocatalytic HER activity. To deliver a current density of 10 mA·cm^-2, it required an overpotential of merely 19 mV along with a Tafel slope of 26.19 mV·dec^-1 in 1 mol·L^-1 potassium hydroxide (KOH) solution, outperforming the benchmark Pt/C catalyst. The present work would pave a new way towards the design and construction of an efficient electrocatalyst for energy storage and conversion.