Chemical Buffer Layer Enabled Highly Reversible Zn Anode for Deeply Discharging and Long‐Life Zn–Air Battery

Abstract

Rechargeable alkaline Zn–air batteries (ZABs) are attracting extensive attention owing to their high energy density and environmental friendliness. However, the dilemma of Zn anode, composed of ineluctable passivation and dissolution problems, severely hinders the discharge and cycling performance of the battery. Herein, the authors propose a chemical buffer layer coated on Zn metal (CBL@Zn) anode, in which ZnO nanorods are uniformly dispersed in graphene oxide (GO), to improve the reversibility of Zn↔ZnO electrochemical conversion process. Benefiting from the cooperative effect of ZnO nanorods’ nuclei role and GO's adsorption affinity, the electrochemical precipitation–dissolution behavior of insulated ZnO is chemically regulated and the Zn(OH)42− ions are effectively confined in the chemical buffer layer. Therefore, the symmetrical CBL@Zn‐CBL@Zn coin cell achieves a superior stability of 100 cycles with quite low overpotential (30 mv). When paired with commercial catalysts to assemble alkaline ZABs for practical use, an ultra high depth of discharge (DODZn) >98% and excellent 450‐h long‐term cycling performance are realized. This chemical buffer strategy can potentially provide a new insight for developing other highly reversible alkaline Zn‐metal batteries.

Janus Hollow Nanofiber with Bifunctional Oxygen Electrocatalyst for Rechargeable Zn–Air Battery

“…The XRD pattern (Figure S11, Supporting Information) also shows that the crystalline phase of NiFe@C@Co CNFs is stable after charge-discharge cycling. While the byproduct K 2 CO 3 was observed on the air cathode in Figures S10 and S11 (Supporting Information), generated by the reaction between KOH and CO 2 in air, [55,56] which is another obstacle to be solved in the research of Zn-air battery. With the above-mentioned results, it can be concluded that NiFe@C@Co CNF is a highly efficient and stable air cathode that benefits from the unique Janus-like hollow structure.…”

Rational Design of Flexible Zn-Based Batteries for Wearable Electronic Devices

“… As the discharge continues, the generated (Zn­(OH) 4 2– ) becomes supersaturated in the electrolyte and further transforms into insoluble zinc oxide (ZnO) (eq ). − Simultaneously, oxygen in the air is reduced to OH – by the oxygen reduction reaction (ORR) on catalyst active sites on the cathode (eq ). , Driven by the concentration gradient, OH – migrates to the anode and cations in the electrolyte migrate in the opposite direction .…”

Research progress on the construction of synergistic electrocatalytic ORR/OER self-supporting cathodes for zinc–air batteries

“…To improve the reversibility of the electrochemical conversion process between Zn and ZnO, Sun et al proposed the coating of the Zn anode with a chemical buffer layer to evenly disperse ZnO nanorods in GO (CBL@Zn). 70 Due to the synergistic effect of the nuclear ZnO nanorods and GO adsorption affinity, the electrochemical deposition/dissolution process of ZnO could be effectively regulated. Zn (OH) 4 2− was effectively conned in the chemical buffer layer, thus effectively eliminating zinc passivation.…”