Enabling selective zinc-ion intercalation by a eutectic electrolyte for practical anodeless zinc batteries

Abstract

Two major challenges hinder the advance of aqueous zinc metal batteries for sustainable stationary storage: (1) achieving predominant Zn-ion (de)intercalation at the oxide cathode by suppressing adventitious proton co-intercalation and dissolution, and (2) simultaneously overcoming Zn dendrite growth at the anode that triggers parasitic electrolyte reactions. Here, we reveal the competition between Zn2+vs proton intercalation chemistry of a typical oxide cathode using ex-situ/operando techniques, and alleviate side reactions by developing a cost-effective and non-flammable hybrid eutectic electrolyte. A fully hydrated Zn2+ solvation structure facilitates fast charge transfer at the solid/electrolyte interface, enabling dendrite-free Zn plating/stripping with a remarkably high average coulombic efficiency of 99.8% at commercially relevant areal capacities of 4 mAh cm−2 and function up to 1600 h at 8 mAh cm−2. By concurrently stabilizing Zn redox at both electrodes, we achieve a new benchmark in Zn-ion battery performance of 4 mAh cm−2 anode-free cells that retain 85% capacity over 100 cycles at 25 °C. Using this eutectic-design electrolyte, Zn | |Iodine full cells are further realized with 86% capacity retention over 2500 cycles. The approach represents a new avenue for long-duration energy storage.

Tetraphenylporphyrin‐based Chelating Ligand Additive as a Molecular Sieving Interfacial Barrier toward Durable Aqueous Zinc Metal Batteries

“…Moreover, the Zn anodes before and after cycling in TPPS/ZnSO 4 electrolyte was subjected to an in‐depth X‐ray photoelectron spectroscopy (XPS) test. As seen from the S 2p spectra in Figure 6d, peaks of SO 4 2− and ZnS from ZnSO 4 appear at 169.5 and 161.6 eV, respectively, while the peak at 166.6 eV is assigned to HSO 3 − species originating from the adsorbed TPPS additive [11,27a,35] . It is noted that the presence of ZnS before etching may ascribe to the residual ZnSO 4 electrolyte on the Zn anode surface.…”

“…The high salt cost and electrolyte viscosity hinder the practical applications of highly concentrated electrolytes [8] . Introducing organic co‐solvents (e.g., ethylene glycol, [9] propylene carbonate, [10] sulfolane [11] ) is considered as a viable alternative to reduce the activity of water. However, these electrolyte systems generally suffer from enlarged de‐solvation barrier, degraded charge transfer kinetics, as well as compromise in safety (e.g., electrolyte flammability) [12] .…”

Highly Stable Aqueous/Organic Hybrid Zinc-Ion Batteries Based on a Synergistic Cathode/Anode Interface Engineering

“…A similar pattern can also be noted in the vibration of -CF 3 (Figure S2). Meanwhile, in the range of 2800–3800 cm –1 , where the O–H stretching bands of water were recorded (Figure d), three types of water molecules, namely “network water (NW)”, “intermediate water (IW)” and “multimer water (MW)”, can be classified according to the Gaussian function of the O–H stretching band. Apparently, the weakly H-bonded NW can be easily interrupted by the introduction of TMP, which is probably associated with the [TMP-OTf-H 2 O] species formed by the salting effect .…”

Toward Practical Multivalent Ion Batteries with Quinone-Based Organic Cathodes

“…The proton-initiated side reactions in aqueous Zn battery systems can be mitigated by modifying the interface to limit the activity of protons, following similar strategies that were recently attempted for inorganic-based cathodes. 69,70 Finally, appropriate applications should be sought for each type of multivalent ion organic battery to make the most of the benefits they provide. To fulfill the rising need for the generation and storage of renewable energy, several advanced battery technologies serving many purposes beyond those requiring a high energy density are expected to be the focus of much research and development.…”