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.

Mass loading and potential plateau are the two most important issues of potassium (K)-ion batteries (KIBs), but they have long been ignored in previous studies. Herein, we report a simple and scalable method to fabricate acidized carbon clothes (A-CC) as high mass loading (13.1 mg cm −2 ) anode for KIBs, which achieved a reversible areal-specific capacity of 1.81 mAh cm −2 at 0.2 mA cm −2 . Besides, we have proposed the concept of "relative energy density" to reasonably evaluate the electrochemical performance of the anode. According to our calculation method, the A-CC electrode exhibited an ultrahigh relative energy density of 46 Wh m −2 in the initial charge process and remained at 40 Wh m −2 after 50 cycles. Furthermore, we performed the operando Raman spectroscopy (ORS) to investigate the K-ion storage mechanism. We believe that our work might provide a new guideline for the evaluation of anode performance, thereby, opening an avenue for the development of commercial anode.

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As one of the promising anode materials, iron selenide has received much attention for potassium-ion batteries (KIBs). Nevertheless, volume expansion and sluggish kinetics of iron selenide result in the poor reversibility and stability during potassiation–depotassiation process. In this work, we develop iron selenide composite matching ether-based electrolyte for KIBs, which presents a reversible specific capacity of 356 mAh g−1 at 200 mA g−1 after 75 cycles. According to the measurement of mechanical properties, it is found that iron selenide composite also exhibits robust and elastic solid electrolyte interphase layer in ether-based electrolyte, contributing to the improvement in reversibility and stability for KIBs. To further investigate the electrochemical enhancement mechanism of ether-based electrolyte in KIBs, we also utilize in situ visualization technique to monitor the potassiation–depotassiation process. For comparison, iron selenide composite matching carbonate-based electrolyte presents vast morphology change during potassiation–depotassiation process. When changing to ether-based electrolyte, a few minor morphology changes can be observed. This phenomenon indicates an occurrence of homogeneous electrochemical reaction in ether-based electrolyte, which results in a stable performance for potassium-ion (K-ion) storage. We believe that our work will provide a new perspective to visually monitor the potassium-ion storage process and guide the improvement in electrode material performance.

To meet the increasing requirement of flexible energy storage devices, it is critical to develop an electrode with commercial-level mass loading of active material for supercapacitors. Herein, we fabricated a...

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