Polymer “Tape”‐Assisted Ball‐Milling Method Fabrication Few‐Atomic‐Layered Bismuth for Improving K+/Na+ Storage

Few‐layered 2D analogs exhibit new physical/chemical properties, leading to a strong research interest and broad areas of application. Recently, lots of methods (such as ultrasonic and electrochemical methods) have already used to prepared 2D materials. However, these methods suffer from the drawbacks of low yield, high cost, or precarious state, which limit the large‐scale applications. Inspired by the famous Scotch tape method, we develop a ball‐milling with polymer “tape” method, fabricating few‐atomic‐layered material, showing the high‐yield, low‐cost, and much stability. As electrode material, ultrathin 2D materials can shorten the ion transfer pathway, contributing to the development of high‐power batteries. Meanwhile, few‐atomic‐layered structure can expose more active sites to increase their capacity, showing special energy storage mechanism. We use the as‐prepared few‐atomic‐layered Bi (FALB) and reduced oxide graphene composites as the anode for potassium/sodium‐ion batteries (KIBs/NIBs). The sample achieves a high reversible capacity of 395 mAh g−1 for KIBs, of which FALB contributes 438 mAh g−1 (higher than the theoretical capacity of Bi, 386 mAh g−1), and it carries outstanding cycle and rate performance in KIBs/NIBs. The few‐atomic‐layered material has been synthesized by a ball‐milling with polymer “tape” method, exhibiting thinner thickness, higher yield, and more stable state than that of nanosheets exfoliated through ultrasonic methods. Additionally, the obtained few‐atomic‐layered bismuth is beyond the alloying capacity (Bi ↔ A3Bi, A = K, Na) due to the many active sites, showing special energy storage mechanism in K+/Na+‐ion batteries.