Electrochemically Derived Graphene‐Like Carbon Film as a Superb Substrate for High‐Performance Aqueous Zn‐Ion Batteries

Abstract

3D graphene, as a light substrate for active loadings, is essential to achieve high energy density for aqueous Zn-ion batteries, yet traditional synthesis routes are inefficient with high energy consumption. Reported here is a simplified procedure to transform the raw graphite paper directly into the graphene-like carbon film (GCF). The electrochemically derived GCF contains a 2D-3D hybrid network with interconnected graphene sheets, and offers a highly porous structure. To realize high energy density, the Na:MnO 2 /GCF cathode and Zn/GCF anode are fabricated by electrochemical deposition. The GCF-based Zn-ion batteries deliver a high initial discharge capacity of 381.8 mA h g −1 at 100 mA g −1 and a reversible capacity of 188.0 mA h g −1 after 1000 cycles at 1000 mA g −1 . Moreover, a recorded energy density of 511.9 Wh kg −1 is obtained at a power density of 137 W kg −1 . The electrochemical kinetics measurement reveals the high capacitive contribution of the GCF and a co-insertion/desertion mechanism of H + and Zn 2+ ions. First-principles calculations are also carried out to investigate the effect of Na + doping on the electrochemical performance of layered δ-MnO 2 cathodes. The results demonstrate the attractive potential of the GCF substrate in the application of the rechargeable batteries.

Oxygen‐Deficient Birnessite‐MnO2 for High‐Performing Rechargeable Aqueous Zinc‐Ion Batteries

“…The maximum energy and power density of other similar recent works reporting on high performance Zn//MnO 2 battery systems were also included in the plot for comparison against our Zn//O dc À MnO 2 battery system. [17,29,40] As observed from the plot, the Zn// O dc À MnO 2 battery system in our work managed to achieve comparable and even better performance than the other Zn// MnO 2 battery systems.…”

Dendrites in Zn‐Based Batteries

“…[282] When summarizing previous works providing the parameter of cathode loading mass, it is apparent to note that the majority of laboratory studies showed low areal capacities of less than 0.3 mAh cm −2 , and the areal current varies from 1 to 12 mA cm −2 (Figure 25). [33,79,80,94,96,280,[283][284][285][286][287][288][289] These areal capacities are extremely low for powering customer electronics. [122] Rather than numerically refreshing the cycling life in laboratory, evaluating the diverse methods of dendrite protection under practical conditions moves toward the realization of dendrite-free Zn metal batteries.…”

Self-assembled α-MnO2 urchin-like microspheres as a high-performance cathode for aqueous Zn-ion batteries

“…Typically, AZIBs consist of an intercalation-type cathode, a zinc metal anode and a Zn 2+ -based aqueous electrolyte, which demonstrate attractive features of large theoretical capacity (820 mA h g −1 and 5855 mA h cm −3 ), wide working potential window (0-2 V), reversible plating/stripping of Zn, high safety, environmental friendliness, low cost and facile manufacturing process [1][2][3][4]. Since Kang's group [5] [6][7][8][9]. Among them, the α-MnO 2 -based AZIBs exhibit the highest specific capacity of more than 380 mA h g −1 , long-term reversibility and extraordinary rate capability, which benefit from their 2×2 tunnel structure with corner-sharing double MnO 6 octahedra chains [10].…”