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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.

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Our synthesized ball-cutting Na-FeHCF nanocubes by controlling the stirring speed as a cathode material for ammonium ion storage exhibit high capacity, excellent rate capability, and unparalleled cycling stability.

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.

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The lithium-sulfur (Li-S) battery has received a lot of attention because it is characterized by high theoretical energy density (2,600 Wh/kg) and low cost. Though many works on the "shuttle effect" of polysulfide have been investigated, lithium metal anode is a more challenging problem, which leads to a short life, low coulombic efficiency, and safety issues related to dendrites. As a result, the amelioration of lithium metal anode is an important means to improve the performance of lithium sulfur battery. In this paper, improvement methods on lithium metal anode for lithium sulfur batteries, including adding electrolyte additives, using solid, and/or gel polymer electrolyte, modifying separators, applying a protective coating, and providing host materials for lithium deposition, are mainly reviewed. In addition, some challenging problems, and further promising directions are also pointed out for future research and development of lithium metal for Li-S batteries.