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Roll‐to‐roll dry processing enables the manufacture of high energy density and low cost Li‐ion batteries (LIBs). However, as the thickness of the electrode fabricated by dry processing becomes greater (≥10 mAh cm−2), Li‐ion migration resistance (Rion) and charge‐transfer resistance (Rct) in the electrode dramatically increase due to long diffusion lengths for Li‐ion and electron. Therefore, it is important to reduce diffusion lengths in the electrode to achieve high energy density LIBs. The dry electrode with a high areal capacity of 10 mAh cm−2 and low resistance can be achieved by following three characteristics. First, the fibrillization behavior of polytetrafluoroethylene (PTFE) binder is controlled by adjusting the processing temperature during the fibrillization process, which enables uniform distribution of PTFE binder and carbon black (CB). Second, pore size/distribution and conducting network are engineered by multi‐dimensional conducting agents, enhancing Li‐ions and electrons transport in the electrode. Finally, the structural integrity of LiNi0.80Co0.15Al0.05O2 (NCA) particles is improved without fractures, which enables uniform pore distribution in the electrode by controlling the calendering step. The prepared 10 mAh cm−2 dry electrode with homogeneous microstructure shows reduced Rion and Rct due to short diffusion lengths, which improves electrochemical performances in LIBs with a high volumetric energy density of ≈710 Wh L−1. [ABSTRACT FROM AUTHOR]

The binder migration due to the capillary force‐driven solvent evaporation during the drying process in the electrode manufacturing process induces inhomogeneous binder distribution in the electrode, which deteriorates Li‐ion kinetics and corresponding poor fast‐charging properties in lithium‐ion batteries (LIBs). Here, we report an effective strategy to mitigate the binder migration behavior by applying an electric field during the drying process. As the employed carboxymethyl cellulose (CMC) and styrene‐butadiene rubber (SBR) binders have a negative charge in an aqueous anode slurry system (pH 7), the binder migration behavior could be mitigated by generating an electrical attraction force into the bottom direction by positive electrification of the current collector. The anode prepared with electric field exhibits homogeneous binder distribution in the longitudinal direction, which enhances Li‐ion kinetics, corresponding constant current charging capacity, and cycling stability compared to those of the anode prepared without electric field. [ABSTRACT FROM AUTHOR]

All‐solid‐state batteries (ASSBs) are expected to be next‐generation energy storage systems due to their high energy density and safety. However, their practical use has been limited by a poor rate capability caused by the Li dendrite growth. Under the operation with high current density, the Li migration rate at the interface between anode and solid electrolyte (SE) is faster than the Li replenishing rate by atom diffusion inside of Li, resulting in void formation at the interface between the anode and SE. These voids induce the increase in the localized current density, leading to the growth of Li dendrites. In this study, an ASSBs system is demonstrated with high rate capability by employing lithiated ZnO nanorods into Li. Lithiated ZnO nanorods, which are capable of Li‐ion conduction, providing the passage for Li transportation from the Li bulk to the interface between the Li and SE, resulting in an improvement in the replenishing rate. The lithiated ZnO nanorods in Li enable interfacial integrity by suppressing the void formation at the Li/SE interface even under the high current density. ASSBs employing Li with lithiated ZnO nanorods exhibit stable cyclability without short circuit at 0.3 C during 300 cycles and excellent rate capability. [ABSTRACT FROM AUTHOR]

Borophosphate materials are promising electrocatalysts for water splitting. Their structural flexibility enable self‐adjusting of electronic structure depending on potential. The rich chemistry of borophosphate provides a huge engineering space to tune composition and structure. Herein, amorphized LiNiFe borophosphate (a‐LNFBPO) for an efficient and durable oxygen evolution reaction (OER) is first reported. Facile adsorption of oxygen intermediates on the vacancies generated by spontaneous Li dissolution during the OER and regulated electronic structure resulting from the Ni and Fe interaction can boost the OER. The amorphization of LiNiFe borophosphate modifies the electronic structure with metal‐oxygen (MO) bond contraction and the high valence state of the metal cations, which reduces the charge transfer energy between the catalyst and electrolyte. In addition, abundant defects, dangling bonds, and a disordered arrangement induced by amorphization enable an improvement in structural flexibility, facilitating a facile and entire transformation of originally inert species into the active phase during the OER process. The a‐LNFBPO@Ni foam shows excellent OER properties requiring only a 215 mV overpotential for generating 10 mA cm−2 and long‐term stability over 300 h. [ABSTRACT FROM AUTHOR]

The development of cost effective and high‐performance electrocatalyst is challenging but essential for realizing industrial hydrogen production by electolyzer. Electrocatalysts for water splitting must have active catalytic performance as well as high stability in strong alkaline or acidic media to be used in commercial elecrolyzer. Transition metal based electrocatalysts are considered as highly promising candidates due to their excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance and stability with low materials cost. Recently, binder free self‐supported electrocatalysts based on transition metals have emerged as state‐of‐the‐art catalytic electrodes due to their high activity and robustness. These properties are attributed to lack of catalyst powder aggregation and a strong synergetic effect between the electrode surface and catalyst. In this mini review, recent development in self‐supported electrocatalysts for OER, HER and also bifunctional OER & HER are reviewed in terms of superior activity and robust stability. Material design strategies, structural and compositional properties, and catalytic performance of recently reported self‐supported electrocatalysts are summarized. Finally, overview of recent studies, challenges and prospects related to self‐supported electrocatalysts are discussed. [ABSTRACT FROM AUTHOR]