Biomass-Derived Anion-Anchoring Nano-CaCO3Coating for Regulating Ion Transport on Li Metal Surface

The free transport of anions in a Li metal battery can cause multiple issues, including a high anion transference number, space charge, and concentration polarization, eventually leading to uncontrolled dendrite formation and decreased performance. Herein, we report an anion-anchoring nano-CaCO3 (NC) coating derived from eggshell biowaste for stabilizing Li metal anodes. As the adsorption of local TFSI– anions onto the NC adsorbent can undermine the anion concentration gradient and promote rapid Li-ion diffusion, it can effectively inhibit the proliferation of Li dendrites assisted by the NC coating. Consequently, Li/Cu cells with NC@Cu electrode can achieve a high Coulombic efficiency of ∼98.4% for more than 420 cycles and can even reach ∼99.1% at an ultrahigh areal capacity of 20 mAh cm–2. In particular, full cells with NC/Li@Cu electrodes show a stable lifespan of over 240 cycles with an average efficiency of ∼99.8% at a low N/P ratio of ∼3.3.