RESUMEN
The use of the "Holy Grail" lithium metal anode is pivotal to achieve superior energy density. However, the practice of a lithium metal anode faces practical challenges due to the thermodynamic instability of lithium metal and dendrite growth. Herein, an artificial stabilization of lithium metal was carried out via the thermal pyrolysis of the NH4F salt, which generates HF(g) and NH3(g). An exposure of lithium metal to the generated gas induces a spontaneous reaction that forms multiple solid electrolyte interface (SEI) components, such as LiF, Li3N, Li2NH, LiNH2, and LiH, from a single salt. The artificially multilayered protection on lithium metal (AF-Li) sustains stable lithium stripping/plating. It suppresses the Li dendrite under the Li||Li symmetric cell. The half-cell Li||Cu and Li||MCMB systems depicted the attributions of the protective layer. We demonstrate that the desirable protective layer in AF-Li exhibited remarkable capacity retention (CR) results. LiFePO4 (LFP) showed a CR of 90.6% at 0.5 mA cm-2 after 280 cycles, and LiNi0.5Mn0.3Co0.2O2 (NCM523) showed 58.7% at 3 mA cm-2 after 410 cycles. Formulating the multilayered protection, with the simultaneous formation of multiple SEI components in a facile and cost-effective approach from NH4F as a single salt, made the system competent.
RESUMEN
Electrochemical stability and interfacial reactions are crucial for rechargeable aqueous zinc batteries. Electrolyte engineering with low-cost aqueous electrolytes is highly required to stabilize their interfacial reactions. Herein, we propose a design strategy using glutamic additive and its derivatives with modification of hydrogen-bonding network to enable Zn aqueous battery at a low concentration (2 m ZnSO4 + 1 m Li2SO4). Computational, in situ/ex situ spectroscopic, and electrochemical studies suggest that additives with moderate interactions, such as 0.1 mol % glutamic additive (G1), preferentially absorb on the Zn surface to homogenize Zn2+ plating and favorably interact with Zn2+ in bulk to weaken the interaction between H2O and Zn2+. As a result, uniform deposition and stable electrochemical performance are realized. The Zn||Cu half-cell lasts for more than 200 cycles with an average Coulombic efficiency (CE) of >99.32% and the Zn||Zn symmetrical cells for 1400 h with a low and stable overpotential under a current density of 0.5 mA cm-2, which is better than the reported results. Moreover, adding 0.1 mol % G1 to the Zn||LFP full cell improves its electrochemical performance with stable cycling and achieves a remarkable capacity of 147.25 mAh g-1 with a CE of 99.79% after 200 cycles.
