Hard carbon (HC) is a promising anode material for sodium ion batteries (SIBs) and potassium ion batteries (PIBs), but the cycle performance is still not satisfactory for practical application, due to the volume change during the insertion/extraction process of Na+ or K+ . [1] Moreover, the poor flexibility of the conventional HC anodes prepared through coating method cannot satisfy the requirement of flexible devices.[2,3] Herein, we propose a very simple but powerful strategy to fabricate flexible HC electrode with excellent structure and cycle stability for SIBs and PIBs by using Ti3C2Tx MXene as a multi-functional buffer binder. By vacuum-assisted filtration of evenly dispersed solution of HC and MXene, the obtained MXene-bonded HC films are flexible, free-standing and can be directly used as anodes for SIBs and PIBs. The elimination of all the inactive components, including polymer binders, conductive additives and current collectors, makes the HC-M films show superior el…