A scalable, ecofriendly, and cost-effective lithium metal protection layer from a Post-it note

Although there have been many studies addressing the dendrite growth issue of lithium (Li)-metal batteries (LMBs), the Li-metal anode has not yet been implemented in today's rechargeable batteries. There is a need to accelerate the practical use of LMBs by considering their cost-effectiveness, ecofriendliness, and scalability. Herein, a cost-effective and uniform protection layer was developed by simple heat treatment of a Post-it note. The carbonized Post-it protection layer, which consisted of electrochemically active carbon fibers and electrochemically inert CaCO₃ particles, significantly contributed to stable plating and stripping behaviors. The resulting protected Li anode exhibited excellent electrochemical performance: extremely low polarization during cycling (<40 mV at a current density of 1 mA cm^-2) and long lifespan (5000 cycles at 10 mA cm^-2) of the symmetric cell, as well as excellent rate performance at 2C (125 mA h g^-1) and long cyclability (cycling retention of 62.6% after 200 cycles) of the LiFePO₄‖Li full cell. The paper-derived Li protection layer offer a facile and scalable approach to enhance LMB electrochemical performance.