Mosaic Nanocrystalline Graphene Skin Empowers Highly Reversible Zn Metal Anodes

Abstract

Constructing a conductive carbon-based artificial interphase layer (AIL) to inhibit dendritic formation and side reaction plays a pivotal role in achieving longevous Zn anodes. Distinct from the previously reported carbonaceous overlayers with singular dopants and thick foreign coatings, a new type of N/O co-doped carbon skin with ultrathin feature (i.e., 20 nm thickness) is developed via the direct chemical vapor deposition growth over Zn foil. Throughout fine-tuning the growth conditions, mosaic nanocrystalline graphene can be obtained, which is proven crucial to enable the orientational deposition along Zn (002), thereby inducing a planar Zn texture. Moreover, the abundant heteroatoms help reduce the solvation energy and accelerate the reaction kinetics. As a result, dendrite growth, hydrogen evolution, and side reactions are concurrently mitigated. Symmetric cell harvests durable electrochemical cycling of 3040 h at 1.0 mA cm −2 /1.0 mAh cm −2 and 136 h at 30.0 mA cm −2 /30.0 mAh cm −2 . Assembled full battery further realizes elongated lifespans under stringent conditions of fast charging, bending operation, and low N/P ratio. This strategy opens up a new avenue for the in situ construction of conductive AIL toward pragmatic Zn anode.

Synchronous Dual Electrolyte Additive Sustains Zn Metal Anode with 5600 h Lifespan

“…[3] Encouragingly, the introduction of GO would offset this drawback: the possible formation of ion transport channel via rGO would drastically decrease the polarization. [31] The nucleation overpotential at different current densities also shows the same trend (Figure S14). To examine the Zn plating/stripping behaviors in different electrolytes, Coulombic efficiency (CE) of TiÀ Zn asymmetric cells equipped with three types of electrolytes was plotted under 10.0 mA cm À 2 /1.0 mAh cm À 2 (Figure 2h; Figure S15).…”

“…Meanwhile, three fitted peaks centering at 531.0, 532.0 and 533.6 eV in the O 1s profile could be assigned to C=O, CÀ O/CÀ OH and OÀ C=O bonding, respectively (Figure 1g). [31] These abundant functional groups of rGO would play a vital role in the Zn electrodeposition. Electrochemical impedance spectroscopy (EIS) profiles of ZnÀ Zn symmetric cells using different electrolytes were further collected to derive the chargetransfer resistance (R ct , Figure 1h).…”

“…The cell with dual-additives has the highest corrosion potential as well as lowest corrosion current density, representing a superior anti-corrosion feature. [31] The inhibitory effect on parasitic side reactions in the presence of dual-additives mainly originates from two aspects: the optimization of Zn 2 + solvation structure by XY and the isolation of water by rGO AIL. To confirm such a synergistic essence, post-mortem X-ray diffraction of Zn anodes after 50 cycles under 1.0 mA cm À 2 /1.0 mAh cm À 2 was carried out (Figure S19).…”

“…Note that the abundant oxygen-containing groups (C=O and OÀ C=O) of rGO could interact with water molecules in the solvated shell, thus facilitating the desolvation process. [31,44] In further contexts, temperature-dependent EIS study was performed to probe the desolvation effect (Figure S20). As expected, the R ct increases slightly at all temperatures with the incorporation of XY into the electrolyte.…”

Construction of an Artificial Interfacial Layer with Porous Structure toward Stable Zinc‐Metal Anodes

“…[ 5 ] The construction of artificial interfacial layer on the surface of zinc metal is an economical and practical strategy to promote reversibility and durability. However, the artificial interfacial layers are normally constructed through ex situ methods, such as knife coating, [ 6 ] evaporation coating, [ 7 ] sputter coating, [ 8 ] spin coating, [ 9 ] and chemical vapor deposition, [ 10 ] which always suffer from the issues of uneven coating, increased electrode thickness, weak adhesion, and easy failure. These issues may result in irregular deposition behavior of Zn 2+ , low energy density, and short cycle life of batteries.…”