Among the negative electrode materials for potassium ion batteries, carbon is very promising because of its low cost and environmental benignity. However, the relatively low storage capacity and sluggish kinetics still hinder its practical application. Herein, a large scalable sulfur/nitrogen dual‐doped hard carbon is prepared via a facile pyrolysis process with low‐cost sulfur and polyacrylonitrile as precursors. The dual‐doped hard carbon exhibits hierarchical structure, abundant defects, and functional groups. The material delivers a high reversible potassium storage capacity and excellent rate performance. In particular, a high reversible capacity of 213.7 and 144.9 mA h g−1 can be retained over 500 cycles at 0.1 A g−1 and 1200 cycles at 3 A g−1, respectively, demonstrating remarkable cycle stability at both low and high rates, superior to the other carbon materials reported for potassium storage, to the best of the authors' knowledge. Structure and kinetics studies suggest that the dual‐doping enhances the potassium diffusion and storage, profiting from the formation of a hierarchical structure, introduction of defects, and generation of increased graphitic and pyridinic N sites. This study demonstrates that a facile and scalable pyrolysis strategy is effective to realize hierarchical structure design and heteroatom doping of carbon, to achieve excellent potassium storage performance.

A pyrolyzed polyacrylonitrile/sulfur nanocomposite (SPAN) was used as a positive electrode material for a room temperature K-S battery operated in carbonate electrolyte. SPAN presented a high reversible capacity of 270 mA h g (710 mA h g) and excellent rate performance, which demonstrate that it is a promising positive electrode material for K-ion and K-batteries.

TiO2-based materials have been widely studied in the field of photocatalysis, sensors, and solar cells. Besides that, TiO2-based materials are of great interest for energy storage and conversion devices, in particular rechargeable lithium ion batteries (LIBs). TiO2has significant advantage due to its low volume change (<4%) during Li ion insertion/desertions process, short paths for fast lithium ion diffusion, and large exposed surface offering more lithium insertion channels. However, the relatively low theoretical capacity and electrical conductivity of TiO2greatly hampered its practical application. Various strategies have been developed to solve these problems, such as designing different nanostructured TiO2to improve electronic conductivity, coating or combining TiO2with carbonaceous materials, incorporating metal oxides to enhance its capacity, and doping with cationic or anionic dopants to form more open channels and active sites for Li ion transport. This review is devoted to the recent progress in enhancing the LIBs performance of TiO2with various synthetic strategies and architectures control. Based on the lithium storage mechanism, we will also bring forward the existing challenges for future exploitation and development of TiO2-based anodes in energy storage, which would guide the development for rationally and efficiently designing more efficient TiO2-based LIBs anodes.

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An acetylene black modified gel polymer electrolyte was prepared to simultaneously solve the problems of shuttle effect and lithium dendrite growth for high-performance Li–S batteries.

Low-cost supercapacitors with high energy densities have attracted great research attention, since it would broaden the application of capacitors. Increasing the capacitance is one principle to obtain a high energy density of a supercapacitor. In this study, a low cost aqueous Zn-based hybrid supercapacitor (AZHS) with high energy density is achieved using an actived carbon derived from corncob (denoted as ACC) as the positive electrode, zinc metal as the negative electrode, and the 2 M ZnSO 4 electrolyte. The actived carbon is prepared with a facile calcination-activation process, and it exhibits high specific surface area (2619 m 2 g −1 ). Though without extra heteroatom doping, ACC demonstrates a superb specific capacitance in acidic, alkaline and neutral electrolytes. The assembled AZHS exhibits a high energy density of 94 W h kg −1 at 68 W kg −1 in a potential window of 0.2−1.8 V, and an excellent cycle stability with only 1.8% capacitance decay is obtained after 10 000 cycles at 5 A g −1 . These results suggest that a low cost supercapacitor with high energy density can be achieved by a hybrid system design using electrodes with high capacitance.

Shearing flow induced spiral self-assembly of multi-shelled nanospheres with unusual chirality in block copolymer micelle system.

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