Controlled Deposition of Zinc‐Metal Anodes via Selectively Polarized Ferroelectric Polymers

Abstract

are highly promising thanks to several advantages: (1) zinc metal possesses high specific capacities (820 mAh g −1 and 5855 mAh cm −3 ); [6] (2) zinc metal has high compatibility in water and a reasonably low electrochemical potential (−0.76 V vs SHE), which enables its application of aqueous battery system with extremely high safety; [7] (3) zinc has higher abundance than lithium in the earth crust, and the mature production technology makes the price of zinc extremely costeffective. [8] However, zinc metal's performance in aqueous ZIBs suffers from several problems, particularly dendrite formation. [9] Many factors can contribute to zinc-dendrite formation, especially the uneven distribution of surface charge density at the anode and the inhomogeneous ion flux in the electrolyte, causing zinc to deposit unevenly and form zinc tips on the surface of the anode. Such as-formed zinc-metal tips tend to exhibit locally concentrated surface charge density and promote the growth of zinc over other areas, which is often referred to as the notorious "tip effect". [10] These zinc tips eventually grow into prominent zinc dendrites during cycling and finally cause an internal battery short circuit (Figure 1, top panel). Thus, a stable zinc-metal anode with dendrite-free deposition behavior is a key requirement for the broad application of aqueous ZIBs.In recent years, suppressing the zinc-dendrite growth in aqueous zinc-ion batteries has attracted widespread research interest. Various approaches have been adopted to fulfill this goal, including optimizing electrolyte components, [11] applying 3D current collectors, [12] and constructing artificial interphases. [13] Constructing artificial interphases before battery assembly is an easy and highly efficient strategy to enable a highly stable zinc anode in operating batteries. [14] These artificial protective layers are generally proposed to introduce physiochemical interactions with zinc, and thus realize its stable deposition. However, most reported artificial protective layers were prepared with a relatively high thickness, [14,15] which would inevitably harm the gravimetric and volumetric specific capacities of the ZIBs. Therefore, designing thin artificial protective layers, which can still achieve a dendrite-free zinc-deposition behavior while minimizing the impact on battery energy density, becomes critical for zinc-metal anodes. Considering the high Young's modulus of zinc, [16] constructing a protective layer to suppress zinc-dendrite growth is a very challenging task.Aqueous zinc-ion batteries are regarded as ideal candidates for stationary energy-storage systems due to their low cost and high safety. However, zinc can readily grow into dendrites, leading to limited cycling performance and quick failure of the batteries. Herein, a novel strategy is proposed to mitigate this dendrite problem, in which a selectively polarized ferroelectric polymer material (poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))) is employed as a surface protective layer on zinc ...

Novel Concept of Separator Design: Efficient Ions Transport Modulator Enabled by Dual‐Interface Engineering Toward Ultra‐Stable Zn Metal Anodes

“…More importantly, such DIE separator modified cells enable performing ultrahigh cumulative capacities reaching up to 8000 and even 9500 mAh cm −2 , not only many times higher than that of the unmodified one (Figure 2d), but also much superior to many other previous reports (Figure 2c). [23,25,31,[35][36][37][38][39][40] To reveal the mechanism behind them, Brunner-Emmet-Teller test (Figure S14, Supporting Information) was first performed to explore the decoration of BTO nanoparticles on influencing the pore size structure of separator. The results reveal that the GF and DIE separator exhibit similar surface area of 2.1 and 1.7 m 2 g −1 , respectively.…”

Highly Reversible Zinc Anode Enabled by a Cation-Exchange Coating with Zn-Ion Selective Channels

“…Designing artificial solid-electrolyte interphase (SEI) films on a Zn anode shows great potential to address the aforementioned issues. − Polymers with good flexibility, high ionic conductivity, and superior processability are regarded as an ideal substance for the generation of artificial SEI films. − However, most of polymer-based artificial SEI films exhibit high polarization and inferior selective access of Zn 2+ ions. Cui et al .…”

Comprehensive review onzinc‐ionbattery anode: Challenges and strategies

“…Similarly, Wang et al developed an effective layer using a ferroelectric polymer material (poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE))), which formed a static electric field between the zinc anode and coating layer that regulated zinc deposition and inhibited zinc dendrites. Symmetric zinc batteries employing this layer demonstrated a long life span of 2000 h at 0.2 mAh cm −2 and an outstanding rate performance with a current density up to 15 mA cm −2 114 . The interaction between the zinc anode and protective barrier plays an important role in defining the adherence force between them.…”

“…Symmetric zinc batteries employing this layer demonstrated a long life span of 2000 h at 0.2 mAh cm À2 and an outstanding rate performance with a current density up to 15 mA cm À2 . 114 The interaction between the zinc anode and protective barrier plays an important role in defining the adherence force between them. Automatically coated or self-assembled protective layers generally possess better stability and strength against electrode volume changes.…”