Given the abundance of potassium resources, potassium-ion batteries are considered a low-cost alternative to lithium-ion types. However, their electrochemical performance remains rather unsatisfactory because potassium ions have sluggish kinetics and large ionic radius. In this study, NiCo₂Se₄ nanotube spheres are synthesized as efficient potassium storage hosts via a facile two-step hydrothermal process. The rationally designed electrode has various ameliorating morphological and functional features, including the following: (i) A hollow structure allows for relief of the volume expansion while offering an excellent electrochemical reactivity to accelerate the conversion kinetics; (ii) a high electrical conductivity for enhanced electron transfer; and (iii) myriad vacancies to supply active sites for electrochemical reactions. As such, the electrode delivers an initial reversible capacity of 458.1 mAh g⁻¹ and retains 346.6 mAh g⁻¹ after 300 cycles at 0.03 A g⁻¹. The electrode sustains a high capacity of 101.4 mAh g⁻¹ even at a high current density of 5 A g⁻¹ and outperforms the majority of state-of-the-art anodes in terms of both cyclic capacity and rate capability, especially at above 1.0 A g⁻¹. This study not only proves bimetallic selenides are promising candidates for potassium storage devices but also offers new insight into the rational design of electrode materials for high-rate potassium-ion batteries.

Inhomogeneous lithium-ion (Li⁺) deposition is one of the most crucial problems, which severely deteriorates the performance of solid-state lithium metal batteries (LMBs). Herein, we discovered that covalent organic framework (COF-1) with periodically arranged boron-oxygen dipole lithiophilic sites could directionally guide Li⁺ even deposition in asymmetric solid polymer electrolytes. This in situ prepared 3D cross-linked network Poly (ACMO-MBA) hybrid electrolyte simultaneously delivers outstanding ionic conductivity (1.02 × 10⁻³ S cm⁻¹ at 30 ℃) and excellent mechanical property (3.5 MPa). The defined nanosized channel in COF-1 selectively conducts Li⁺ increasing Li⁺ transference number to 0.67. Besides, The COF-1 layer and Poly(ACMO-MBA) also participate in forming a boron-rich and nitrogen-rich solid electrolyte interface to further improve the interfacial stability. The Li‖Li symmetric cell exhibits remarkable cyclic stability over 1000 h. The Li‖NCM523 full cell also delivers an outstanding lifespan over 400 cycles. Moreover, the Li‖LiFePO₄ full cell stably cycles with a capacity retention of 85% after 500 cycles. the Li‖LiFePO₄ pouch full exhibits excellent safety performance under pierced and cut conditions. This work thereby further broadens and complements the application of COF materials in polymer electrolyte for dendrite-free and high-energy-density solid-state LMBs.