High-Mass-Loading Electrodes for Advanced Secondary Batteries and Supercapacitors

The growing demand for advanced electrochemical energy storage systems (EESSs) with high energy densities for electric vehicles and portable electronics is driving the electrode revolution, in which the development of high-mass-loading electrodes (HMLEs) is a promising route to improve the energy density of batteries packed in limited spaces through the optimal enlargement of active material loading ratios and reduction of inactive component ratios in overall cell devices. However, HMLEs face significant challenges including inferior charge kinetics, poor electrode structural stability, and complex and expensive production processes. Based on this, this review will provide a comprehensive summary of HMLEs, beginning with a basic presentation of factors influencing HMLE electrochemical properties, the understanding of which can guide optimal HMLE designs. Rational strategies to improve the electrochemical performance of HMLEs accompanied by corresponding advantages and bottlenecks are subsequently discussed in terms of various factors ranging from inactive component modification to active material design to structural engineering at the electrode scale. This review will also present the recent progress and approaches of HMLEs applied in various EESSs, including advanced secondary batteries (lithium-/sodium-/potassium-/aluminum-/calcium-ion batteries, lithium metal anodes, lithium-sulfur batteries, lithium-air batteries, zinc batteries, magnesium batteries) and supercapacitors. Finally, this review will examine the challenges and prospects of HMLE commercialization with a focus on thermal safety, performance evaluation, advanced characterization, and production cost assessment to guide future development.