Highly Reversible Zn Metal Anodes Realized by Synergistically Enhancing Ion Migration Kinetics and Regulating Surface Energy

Abstract

The Zn metal anode suffers from uncontrollable dendrite formation and intricate parasitic reactions that dramatically impede the commercialization of aqueous Zn metal batteries (AZMBs). This st proposes synergistic strategies for facilitating Zn 2+ migration kinetics and regulating surface energy to achieve dendrite-free Zn deposition and suppressing self-corrosion by covering Zn anode with multifunctional covalent organic frameworks possessing sulfonate-rich (SO 3 H) covalently-tethered nanochannels (SCOFs). Benefiting from the vital interplay between SO 3 H and Zn 2+ , the SCOFs coatings form ample Zn 2+ accelerated transport channels to extract Zn 2+ from the electrolyte quickly, thereby promoting rapid desolvation of hydrated Zn 2+ , enhancing ion replenishment capability, and guaranteeing a steady stream of Zn 2+ flux for endowing uniform and compact nucleation. Additionally, the zincophilic SCOFs significantly reduce the surface energy of the Zn (002) crystal plane, inducing preferentially crystallographic (002) orientation electroplating growth. Consequently, the SCOFs-coated Zn anodes (SCOFs@Zn) demonstrate an excellent lifespan up to 4000 h at 5 mA cm −2 , 1 mAh cm −2 , and 3000 h at 5 mA cm −2 , 2 mAh cm −2 . Meanwhile, the full cell paired with the MnO 2 cathode sustains remarkable reversibility within 1000 cycles. The synergistic approach to manipulating ion migration and surface energy provides new insights into developing highly stable AZMBs.

Bioinspired Separator with Ion-Selective Nanochannels for Lithium Metal Batteries

“…Here, temperature-dependent EIS measurements were carried out to investigate the Li + desolvation of EAA75 separator (Figure S8). The activation energy ( E a ) of ion desolvation can be obtained by the linear fitting ln( R ct –1 ) vs 1/ T according to Arrhenius formula: 1 / italicR ct = A nobreak0em0.25em⁡ exp ( − E a / R T ) As shown in Figure f, the activation energy of EAA75 separator is 44.56 kJ mol –1 , lower than that of PE separator ( E a = 59.26 kJ mol –1 ). The lower E a of EAA75 separator means the faster Li + migration and the carboxyl groups are beneficial to the desolvation of Li + , resulting the faster ion transfer kinetics. − Furthermore, the hydrogen bonding between PF 6 – and −COOH decreases the concentration polarization through anchoring the PF 6 – to alleviate the concentration polarization.…”

Cation and Anion Modulation Strategies toward Ideal Zinc Artificial Interface

“…The homogeneous pore structure has a high specific surface area, providing sufficient zincophilic sites, short and open ion diffusion channels, more uniform electric field and concentration field, which is expected to accelerate the diffusion of Zn 2 + and limit the occurrence of competitive side reactions. At present, pore structure engineering as a strategy to regulate Zn 2 + flux mainly focuses on the construction of two-dimen-sional (2D) nanopores [10] and three-dimensional (3D) frameworks.…”

“…Recently, developing artificial interface layer with strong coordination with Zn 2+ has aroused attention. Due to the coordination interaction with Zn 2+ , the ASEI affects the Zn 2+ distribution and diffusion behavior, [28] which can optimize the Zn stripping/plating behavior [10] and improve the electrochemical polarization and nucleation overpotentials [29] . Specifically, the artificial layer modification would change the nucleation barrier on the Zn surface, which is highly related to electrical field, ion concentration and surface energy, thus affecting the nucleation overpotential [30] .…”

Covalent Organic Frameworks in Aqueous Zinc‐Ion Batteries

“…proposed the use of multifunctional sulfonic acid‐rich COF films (SCOFs) coated with zinc anodes to achieve dendrite‐free zinc anodes and inhibition corrosion by enhancing Zn 2+ migration kinetics from the perspective of regulating crystal surface energy (Figure 8c). [90] The pro‐zinc interactions between SCOFs and zinc foil greatly decreased the surface energy of the Zn (002) crystal plane, which makes Zn deposition preferentially grow toward the (002) crystal plane and prevents uncontrollable dendrite formation. As a result, SCOFs@Zn exhibited extremely stable and long cycle life of more than 3000 h and 4000 h at both 5 mA cm −2 , 2 mAh cm −2 , and 5 mA cm −2 , 1 mAh cm −2 , respectively (Figure 8d).…”