Aqueous Zn batteries have high safety, low cost, and the potential to deliver energy density comparable to that of alkali-ion batteries. However, their practical application is largely hampered by the limited cycle life associated with Zn anodes under conditions of high depth of discharge and high current densities. In this work, we report on electrodeposited indium−zinc alloy anodes that have well-dispersed zinc domains surrounding indium domains that form porosity during discharge, which enhances tolerance to dendrites. The InZn anodes (∼8−15% In) exhibit low polarization of ∼5−25 mV and demonstrate 700 cycles at 10 mA cm −2 and 45% depth-of-discharge. Full cells with an InZn anode and dibenzo[b,i]thianthrene-5,7,12,14-tetraone (DTT) cathode in 2 M ZnSO 4 deliver a capacity of ∼110 mAh g −1 and good stability over 40 cycles. The work reveals a rational design of Zn-based anodes toward practical battery applications and opens the door to future development of aqueous Zn batteries.
Zinc-based batteries have attracted extensive attention in recent years, due to high safety, high capacities, environmental friendliness, and low cost compared to lithiumion batteries. However, the zinc anode suffers primarily from dendrite formation as a mode of failure in the mildly acidic system. Herein, we report on electrochemically deposited zinc (ED Zn) and copper−zinc (brass) alloy anodes, which are critically compared with a standard commercial zinc foil. The film electrodes are of commercially relevant thicknesses (21 and 25 μM). The electrodeposited zinc-based anodes exhibit low electrode polarization (∼0.025 V) and stable cycling performance in 50 cycle consecutive experiments from 0.26 to 10 mA cm −2 compared to commercial Zn foil. Coulombic efficiencies at 1 mA cm −2 were over 98% for the electrodeposited zinc-based materials and were maintained for over 100 cycles. Furthermore, full cells with an electrodeposited Zn/brass anode, electrolytic manganese dioxide (EMD) cathode, in 1 M ZnSO 4 + 0.1 M MnSO 4 delivered capacities of 96.3 and 163 mAh g −1 , respectively, at 100 mA g −1 compared to 92.1 mAh g −1 for commercial Zn. The electrodeposited zinc-based anodes also show better rate capability, delivering full cell capacities of 35.9 and 47.5 mAh g −1 at a high current of up to 3 A g −1 . Lastly, the electrodeposited zinc-based anodes show enhanced capacity for up to 100 cycles at 100 mA g −1 , making them viable anodes for commercial use.
Solid–electrolyte
interphases is essential for stable cycling
of rechargeable batteries. The traditional approach for interphase
design follows the decomposition of additives prior to the host electrolyte,
which, as governed by the thermodynamic rule, however, inherently
limits the viable additives. Here we report an alternative approach
of using a nonsacrificial additive. This is exemplified by the localized
high-concentration electrolytes, where the fluoroethylene carbonate
(FEC) plays a nonsacrificial role for modifying the chemistry, structure,
and formation mechanism of the cathode–electrolyte interphase
(CEI) layers toward enhanced cycling stability. On the basis of ab
initio molecular dynamics simulations, we further reveal that the
unexpected activation of the otherwise inert species in the interphase
formation is due to the FEC–Li+ coordinated environment
that altered the electronic states of reactants. The nonsacrificial
additive on CEI formation opens up alternative avenues for the interphase
design through the use of the commonly overlooked, anodically stable
compounds.
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