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Metal-organic framework-derived NiCo 2.5 S 4 microrods wrapped in reduced graphene oxide (NCS@RGO) were synthesized for potassium-ion storage.Upon coordination with organic potassium salts,N CS@RGO exhibits an ultrahigh initial reversible specific capacity (602 mAh g À1 at 50 mA g À1 ) and ultralong cycle life (a reversible specific capacity of 495 mAh g À1 at 200 mA g À1 after 1900 cycles over 314 days). Furthermore,t he battery demonstrates ah igh initial Coulombic efficiency of 78 %, outperforming most sulfides reported previously.A dvanced ex situ characterization techniques,i ncluding atomic force microscopy, were used for evaluation and the results indicate that the organic potassium salt-containing electrolyte helps to form thin and robust solid electrolyte interphase layers,w hichr educe the formation of byproducts during the potassiation-depotassiation process and enhance the mechanical stability of electrodes.T he excellent conductivity of the RGO in the composites,a nd the robust interface between the electrodes and electrolytes,i mbue the electrode with useful properties;i ncluding,u ltrafast potassium-ion storage with areversible specific capacity of 402 mAh g À1 even at 2Ag À1 .

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We are the first to utilize reduced graphene oxide (RGO) wrapped metal organic framework-derived FeS2 hollow nanocages (FeS2@RGO) as an anode for K-ion batteries.

In this work, an ether‐based electrolyte is adopted instead of conventional ester‐based electrolyte for an Sb2O3‐based anode and its enhancement mechanism is unveiled for K‐ion storage. The anode is fabricated by anchoring Sb2O3 onto reduced graphene oxide (Sb2O3‐RGO) and it exhibits better electrochemical performance using an ether‐based electrolyte than that using a conventional ester‐based electrolyte. By optimizing the concentration of the electrolyte, the Sb2O3‐RGO composite delivers a reversible specific capacity of 309 mAh g−1 after 100 cycles at 100 mA g−1. A high specific capacity of 201 mAh g−1 still remains after 3300 cycles (111 days) at 500 mA g−1 with almost no decay, exhibiting a longer cycle life compared with other metallic oxides. In order to further reveal the intrinsic mechanism, the energy changes for K atom migrating from surface into the sublayer of Sb2O3 are explored by density functional theory calculations. According to the result, the battery using the ether‐based electrolyte exhibits a lower energy change and migration barrier than those using other electrolytes for K‐ion, which is helpful to improve the K‐ion storage performance. It is believed that the work can provide deep understanding and new insight to enhance electrochemical performance using ether‐based electrolytes for KIBs.

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As one of the most promising candidates in wearable energy storage devices, aqueous fibrous zinc metal batteries (AFZMBs) remain limited by some severe challenges, such as short life span and unstable capacity performance, etc. In this work, the stability of AFZMB is extended by fabricating an innovative stratified deposition framework (SDF) anode. The as‐prepared SDF electrode can achieve a stratified deposition of Zn metals from the bottom layer to the top layer due to the different overpotentials and binding energy of Zn deposition. Compared with commercial Zn fibers, this dexterous structure provides enough deposition space for Zn metals between the separator and the electrode, dramatically alleviating conventional dendrite puncture and prolonging life expectancy by an order of magnitude. It is found that SDF/AFZMB exhibits a long circulation of 2000 cycles with 89.0% capacity retention at 5 C with superior flexibility, demonstrating potential for application in future wearable electronics.