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The selenium (Se) electrochemistry plays a critical role in developing new generation electrochemical energy storage systems beyond the ever-dominating lithium based era. However, fast kinetics and stable Se electrochemistry still remain great challenges, particularly involving K+ reaction instead of Li+. Herein, we report a facile carbon host using pore structure regulation strategy, in which the abundant micropores provide large specific surface area and pore volume that can physically confine and accommodate the small molecular Se. These micropores not only boost the fast reaction kinetics of small molecular Se with K+, but also can restrain the shuttle effect of polyselenides effectively during the reversible reaction. The ordered and interconnected macropores and mesopores can offer rapid mass transfer channels, together with the chemical adsorption from the N-doping, synergistically improving the charger transfer efficiency and reversible stability. The Se/nitrogen-doped macro-/meso-/microporous carbon (Se@NM3C) delivers large specific capacity of 728 mA h g−1 (0.05C), remarkable rate performance, and superior cycling stability. A novel potassium ion (K-ion) capacitors based on this Se–K electrochemistry (Se–KICs) can achieve high energy/power densities and great long-term service life (86% after 10,000 cycles at 2 A g−1). This work unveils insights into chalcogen based electrochemistry for high performance electrochemical energy storage systems. Fast kinetics and stable Se electrochemistry remain great challenges, particularly involving K+ reaction instead of Li+. This manuscript reports a delicate carbon host pore structure regulation strategy, which enables fast and super stable Se–K electrochemistry through precisely physical and chemical confinement. Based upon this, the assembled novel K-ion capacitors (Se–KICs) display high energy/power densities and great long term service life. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon materials possessing many merits including chemical stability, large specific surface, high electrical conductivity, low cost and easy to synthesize have considered as promising electrode materials for electrochemical energy storage devices. Especially, three-dimensional (3D) ordered hierarchically porous carbon (3D OHPC) materials templated from colloidal crystals have attracted much attention. These materials have special advantages such as 3D continuous carbon network that can enhance the charge transfer, interconnected ordered macropores that can promote the rapid diffusion of electrolyte/ions, and meso- or micropores that can provide high surface areas and accommodate guest active materials. In the present review, the synthetic strategies and main features for two main structures of 3D OHPC, inverse opal and opal, are reported and concisely described. Recent progresses in the alkali-metal ion batteries based on 3D OHPC, such as Li-ion batteries, Na-ion batteries, K-ion batteries, Li–S(Se) batteries, are discussed. At last, current challenges in the controlled synthesis of 3D OHPC-based electrode and prospects for the applications in alkali-metal ion batteries are proposed. The review could offer a guidance for rational design and synthesis of 3D OHPC materials toward alkali metal-ion batteries with high-performances. [Display omitted] [ABSTRACT FROM AUTHOR]