A Protective Layer of UIO-66/Reduced Graphene Oxide to Stabilize Zinc-Metal Anodes toward High-Performance Aqueous Zinc-Ion Batteries.

Rechargeable aqueous Zn-ion batteries with a Zn anode hold great promise as promising candidates for advanced energy storage systems. The construction of protective layer coatings on Zn anode is an effective way to suppress the growth of Zn dendrites and water-induced side reactions. Herein, we reported a series of UIO-66 materials with different concentrations of reduced graphene oxide (rG) coated onto the surface of Zn foil (Zn@UIO-66/rGx; x = 0.05, 0.1, and 0.2). Benefiting from the synergistic effect of UIO-66 and rG, symmetric cells with Zn@UIO-66/rGx (x = 0.1) electrodes exhibit excellent reversibility (e.g., long cycling life over 1100 h at 1 mA cm-2/1 mAh cm-2) and superior rate capability (e.g., over 1100 and 400 h at 5 mA cm-2/2.5 mAh cm-2 and 10 mA cm-2/5 mAh cm-2, respectively). When the Zn@UIO-66/rG0.1 anode was paired with the NaV3O8·1.5H2O (NVO) cathode, the Zn@UIO-66/rG0.1||NVO cell also delivered a high reversible capacity of 189.9 mAh g-1 with an initial capacity retention of 61.3% after 500 cycles at 1 A g-1, compared to the bare Zn||NVO cell with only 92 cycles.

From graphite of used lithium-ion batteries to holey graphite coated by carbon with enhanced lithium storage capability.

The efficient recycling of waste graphite anode from used lithium-ion batteries (LIBs) has attracted considerable concerns mainly owing to the environment protection and reutilization of resources. Herein, we reported a rational and facile strategy for the synthesis of holey graphite coated by carbon (hG0.01@C0.10) through the separation, purification and creation of holey structures of waste graphite by using NaOH and carbon-coating by using phenolic resin. The holey structures facilitate the hG0.01@C0.10 with the quick penetration of electrolytes and rapid diffusion of Li+. The carbon coating is more favorable for hG0.01@C0.10 with improved electronic conductivity and less alleviated volume during the cycles. Benefiting from the synergistic effect of holey structures and carbon coating, the hG0.01@C0.10 as anode for LIBs displays a high reversible capacity of 377.6 mAh g-1 at 0.5 C and superior rate capabilities (e.g., 348.0 and 274.7 mAh g-1 at 1 and 2 C, respectively) and maintains a high reversible capacity of 278.7 mAh g-1 at 1 C after 300 cycles with an initial capacity retention of 80.0 %.