3D hierarchical graphene matrices enable stable Zn anodes for aqueous Zn batteries

Abstract

Metallic zinc anodes of aqueous zinc ion batteries suffer from severe dendrite and side reaction issues, resulting in poor cycling stability, especially at high rates and capacities. Herein, we develop two three-dimensional hierarchical graphene matrices consisting of nitrogen-doped graphene nanofibers clusters anchored on vertical graphene arrays of modified multichannel carbon. The graphene matrix with radial direction carbon channels possesses high surface area and porosity, which effectively minimizes the surface local current density, manipulates the Zn2+ ions concentration gradient, and homogenizes the electric field distribution to regulate Zn deposition. As a result, the engineered matrices achieve a superior coulombic efficiency of 99.67% over 3000 cycles at 120 mA cm−2, the symmetric cells with the composite zinc anode demonstrates 2600 h dendrite-free cycles at 80 mA cm−2 and 80 mAh cm−2. The as-designed full cell exhibits an inspiring capacity of 16.91 mAh cm−2. The Zn capacitor matched with activated carbon shows a superior long-term cycle performance of 20000 cycles at 40 mA cm−2. This strategy of constructing a 3D hierarchical structure for Zn anodes may open up a new avenue for metal anodes operating under high rates and capacities.

Synergistic effects of Lewis acid–base and Coulombic interactions for high-performance Zn–I2 batteries

“…[1][2][3][4][5] Among the series of aqueous batteries, zinciodine (Zn-I 2 ) batteries have attracted significant research attention due to their low cost (75 ppm Zn in Earth's crust and abundant iodine in ocean, 50-60 mg L À1 ), 6 the immanent safety of the aqueous electrolyte, and relatively high theoretical capacities of Zn (820 mA h g À1 or 5855 mA h cm À3 ) and I 2 (211 mA h g À1 ). [7][8][9][10][11] Besides, the intrinsic conversion process of iodine batteries with complete electron exchange produces a flat voltage plateau, which has incomparable advantages compared with that of intercalation-type cathode materials. [12][13][14][15] Nevertheless, the restricted lifespan of Zn-I 2 batteries is far from adequate and is a severe setback to their further progress.…”

Solvation structure regulation of an organic small molecule additive for dendrite-free aqueous zinc-ion batteries

“…13 To make matters worse, irregularly shaped zinc dendrite particles tend to puncture the separator, resulting in a short circuit in the battery. 14–16 To alleviate the above problems, researchers have proposed strategies such as constructing artificial interfacial layers, 17 modifying collectors, 18 optimizing the internal structure of the zinc anode, 19 modifying the separator, 20 and increasing the salt concentration 21 to protect the Zn anode from the deleterious reactions associated with aqueous electrolyte. While these methods provide new insights into zinc metal protection, they are difficult to implement from the perspective of manufacturing process and production cost.…”

MOF nanosheets as ion carriers for self-optimized zinc anodes

“…Numerous solutions have been proposed to address inhomogeneous electric field issues from the perspective of substrate homogenization. 20–30 For example, various protective layers, such as solid electrolyte interphase (SEI), 31–33 TiO 2 , 34,35 metal organic frameworks (MOFs), 36,37 self-assembled multilayer 38 and polyamide (PA), 39 have been used to homogenize the electric field distribution at the electrode–electrolyte interfaces and isolate Zn anode from water corrosion. However, the micrometer-level thickness of the protective layers retards the diffusivity of Zn 2+ and limits its high-rate performance.…”

“…Another class of solutions is to reconstruct Zn anode structures. 25,29,30,40–43 Among these methods, alloying and pretreatment of zinc anodes are usually adopted to rectify the initial surface unevenness, while the limited thickness of heteroepitaxial or homoepitaxial zinc deposition poses a challenge to long-term battery cycling. Although the adsorption of additives, including ions, small molecules and nanoparticles, at the electrode/electrolyte interface could inhibit side reactions and influence the nucleation and growth of Zn, 44–51 it is important to note that the substrate inhomogeneity and variations in the electric field persist.…”