Recently, nonaqueous potassium-ion batteries (KIBs) are attracting because of increasing interest due to the abundance of potassium resources, but the systematic study about the effects of electrolyte's salt on the electrochemical performance of electrode materials is still insufficient. Here, it is shown that the capacity retention and Coulombic efficiency of commercial micrometric MoS 2 can be remarkably improved by simply using potassium bis(fluorosulfonyl)imide (KFSI) over potassium hexafluorophosphate (KPF 6 ) dissolved in ethylene carbonate/diethyl carbonate as the electrolyte. By constructing various cell configurations, it is discovered that the degradation of MoS 2 ||K half-cells in KPF 6 -containing electrolyte originates from the failure of the MoS 2 electrode. The solid electrolyte interphase (SEI) layer formed on MoS 2 during cycling was systematically investigated by using a series of characterizations. It is found that a stable, protective, and KF-rich SEI layer is formed on MoS 2 in the KFSI-containing electrolyte, while an unstable, KF-deficient, and organic species-rich SEI layer is formed in the KPF 6 -containing electrolyte. Finally, the origins of such differences are discussed, which will provide new insights into further exploration of novel electrolytes for KIBs.

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The application of a layered K0.5MnO2 cathode in potassium-ion batteries is limited by its poor cycling performance when charged above 4.0 V (vs K+/K), and the underlying mechanism for this electrochemical instability is still unclear. Here, it is discovered that ethylene carbonate (EC) will intercalate into the depotassiated K0.5MnO2, causing the exfoliation of the layered compound and the capacity decay under high charge cutoff voltage. When the carbonates are replaced with a nonflammable phosphate, the electrochemical performance of K0.5MnO2 above 4.0 V (vs K+/K) is significantly enhanced with a large reversible capacity (120 mAh g–1) and high capacity retention of 84% after 400 cycles. This phosphate-based electrolyte also demonstrates good compatibility with the commercial graphite anode, enabling the encouraging electrochemical performance of the K0.5MnO2|graphite full-cell. The present study provides new insights on further exploration of other electrolytes to advance the emerging low-cost and high-performance potassium-ion batteries.

Tumor fibrotic stroma forms complex barriers for therapeutic nanomedicine. Although nanoparticle vehicles are promising in overcoming biological barriers for drug delivery, fibrosis causes hypoxia, immunosuppression and limited immunocytes infiltration, and thus reduces antitumor efficacy of nanosystems. Herein, we report the development of cancer‐associated fibroblasts (CAFs) responsive honeycomb‐like nanoassemblies of carbon dots (CDs) to spatially program the delivery of multiple therapeutics for enhanced antitumor chemoimmunotherapy. Doxorubicin (DOX) and immunotherapeutic enhancer (Fe ions) are immobilized on the surface of CDs, whereas tumor microenvironment modifier (losartan, LOS) is encapsulated within the mesopores. The drugs‐loaded nanoassemblies disassociate into individual CDs to release LOS to mitigate stroma and hypoxia in response to CAFs. The individual CDs carrying DOX and Fe ion efficiently penetrate deep into tumor to trigger intensified immune responses. Our in vitro and in vivo studies show that the nanoassemblies exhibit effective T cells infiltration, tumor growth inhibition and lung metastasis prevention, thereby providing a therapeutic platform for desmoplasia solid tumor.

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