Confinement of Zinc Salt in Ultrathin Heterogeneous Film to Stabilize Zinc Metal Anode

Abstract

Aqueous zinc metal batteries (AZMBs) have drawn great attention due to the high theoretical capacity, low redox potential, and abundance reserves. However, the practical application of rechargeable AZMBs are hindered by the poor reversibility of Zn metal anode, owing to easy dendrite growth and serious side reactions. Herein, the preparation of heterogeneous interfacial film with highly dispersed and confined zinc salt in a 2D channel by coassembling polyamide 6, zinc trifluoromethanesulfonate, and layered double hydroxides, which significantly suppresses the dendrite formation, H2 evolution reaction as well as O2 corrosion is reported. The as‐developed Zn anodes exhibit a long cycling life up to 1450 h with low reversible deposition potential. Moreover, the assembled Zn||Mn battery delivers a high initial capacity of 321 mAh g−1 and a low capacity decay of ≈0.05% per cycle after 590 cycles, which is promising for high‐performance AZMBs. A fluorescent film to realize the in situ observation of the Zn anode during cycling, which provides a new chance for visual observation of the working state of the Zn interface, is also assembled.

Strategies of regulating Zn2+solvation structures for dendrite-free and side reaction-suppressed zinc-ion batteries

“…For instance, an ultrathin film composed of polyamide 6 (PA6), zinc trifluoromethane-sulfonate (Zn(TfO) 2 ) and layered double hydroxides (LDHs) (PA6/Zn(TfO) 2 /LDH) was reported to stabilize Zn metal anodes. 289 The interlayer space between PA6 and LDHs achieved the robust confinement of Zn(TfO) 2 via unique hydrogen bond networks in the PA6/Zn(TfO) 2 /LDH film (Fig. 11h), which could not only boost the fast and homogeneous Zn 2+ diffusion at the interface, but also significantly prevent the erosion of Zn metal anodes from H 2 O/O 2 to avoid the decomposition of electrolyte.…”

“…11h), which could not only boost the fast and homogeneous Zn 2+ diffusion at the interface, but also significantly prevent the erosion of Zn metal anodes from H 2 O/O 2 to avoid the decomposition of electrolyte. 289 Moreover, a cellulose nanowhisker-graphene (CNG) membrane, assembled with graphenes (GNs) and cellulose nanowhiskers (CNWs) could also function as a de-solvation layer to prevent H 2 O molecules from encountering the anode surface. 286 The researchers demonstrated that the CNWs showed strong interaction with H 2 O molecules and [Zn(H 2 O) 6 ] 2+ complexes due to the high adsorption energy, and the CNG membrane could attract [Zn(H 2 O) 6 ] 2+ and then take off H 2 O molecules via hydrogen bond interaction (Fig.…”

“…The super-saturated electrolyte layers for stabilizing zinc metal anodes and the corresponding electrochemical performance are summarized in Table 5. 90,182,286–289 These functional layers enable the hydrated Zn 2+ ions to de-solvate before reaching the surface of the zinc anode via hydrogen bonding or electric field, which prevents the direct contact between active H 2 O molecules and the zinc metal, thereby suppressing the HER, corrosion and byproduct formation. 290–292 Generally, this pre-desolvation process requires these functional layers to have a suitable internal fine structure to reject hydrated Zn 2+ ions.…”

High cycle stability of Zn anodes boosted by an artificial electronic–ionic mixed conductor coating layer

“…For the organic ion regulators, the polarization is generally very high, which hinders the rate performance of the battery. [28][29][30][31][32] The inorganic ion regulators were reported with small polarization, yet they either go through multiple preparation procedures, 33 or improved mechanical properties of the coating layer are requested. 34 Thus, it is signicant to explore the surface coating layer for Zn anodes to alleviate the disadvantages of electron or ion regulators, in the meantime, with a facile preparation method.…”

LiCoO2 Ultrathin Layer for Uniform Lithium Deposition toward a Highly Stable Lithium Metal Anode

“…To induce a homogeneous plating/stripping, considerable efforts have been devoted, i.e., developing new/highly concentrated electrolytes, fabricating an artificial solid electrolyte interface (SEI), and introducing solid electrolyte. − Another effective strategy is engineering a three-dimensional (3D) framework collector to decrease local current density that induces uniform Li nucleation and prevents dendrite growth . The 3D frameworks with porous structures provide buffer spaces to reduce volume changes. − However, these 3D frameworks generally fail to display lithiophilicity, which results a high nuclear barrier and makes it impossible to use directly for metal anode collectors.…”