Utilization of Hyper-Dendritic Zinc during High Rate Discharge in Alkaline Electrolytes

Abstract

Zinc is a low cost and abundant material, and its strong reducing potential combined with stability in aqueous solutions give it high energy density and safety. It is, therefore, known to be an excellent choice of anode for a wide range of battery designs. However, this material presents some challenges for use in a secondary battery, including morphology changes and dendrite growth during charge (Zn deposition), and low utilization during discharge (Zn dissolution). Low utilization is related to a combination of corrosion and passivation effects. In this paper, we demonstrate a hyper-dendritic (HD) zinc morphology that has a high surface area and allows for rapid discharge in a completely freestanding system with no binders or conductive additives, while still maintaining significantly higher utilization than typical zinc morphologies. At rates of 2.5 A/g, the HD zinc has a utilization level approximately 50% higher than typical zinc granules or dust. Furthermore, we demonstrate that, through tuning of the electrolyte with specific additives, we are able to further increase the utilization of the material at high rate discharge by up to 30%. Zinc possesses many characteristics that are favorable for large scale energy storage: high volumetric energy density, low cost, low toxicity, global abundance, and chemical compatibility with aqueous electrolytes.1 As an example of a zinc battery application, silver-zinc batteries have been successfully used as primary and secondary cells in a range of demanding applications, including those requiring large scale, high power and high energy density. These include critical military and space applications.However, zinc electrodes present some significant challenges, and anode failure is a key factor in the reduced cycle life of these batteries. 2These challenges include morphology changes and dendrite growth during deposition, 3 which can lead to problems such as the short circuit of a cell, and poor utilization efficiencies during dissolution, arising mainly from corrosion and passivation effects.1 As such, typical zinc utilization levels are limited to 60% or less. 4,5 Careful engineering and materials science can extend the cycle life of the electrode; however, the issues of morphology change and poor utilization still present major limitations for secondary batteries with a zinc electrode. 2,6 A range of battery designs have been proposed to address some of the morphology-related problems: flow-based designs, fuel cell-like designs, and novel electrode architectures.In flow-based systems, redox flow batteries based on chemistries such as ZnBr and ZnFe attempt to mitigate changes in electrode morphology during cycling by continuously reforming the cathode and anode. However, these systems can suffer from low energy density 7 due to the limited solubility of the dissolved redox species. Other battery designs proposed include semi-solid and flow-assisted designs where the active material is refreshed periodically.8 These flow based approaches suffer from a significant energ...

Dendrites in Zn‐Based Batteries

“…[111] In addition, the rapid corrosion of the Zn anode that leads to the apparent shape change also aggravates dendrite formation. [112,113] These alkaline Zn dendrites show a 1D ramified cone-like topology, which is likely to easily pierce the separators (Figure 5a,b). [34] They can form even under moderate conditions of low capacity and current density, implying that their origin lies in thermodynamic instability.…”

Dendritic Zn Deposition in Zinc‐Metal Batteries and Mitigation Strategies

“…Electrolyte additives in platting solution are considered a promising approach to control parasitic side reactions on Zn‐metal anode and the dendrite suppression. [ 78–80 ] The effect of organic and inorganic additives of Triton X‐100, sodium lauryl sulfate, and Pb 2+ to suppress Zn dendrite in Zn‐polyaniline batteries made with Zn‐metal anode is reported by Kan et al [ 81 ] They have shown that the presence of additives results in smooth and uniform Zn deposition. Tetra‐alkyl ammonium hydroxides are also shown to suppress Zn dendrite in Zn−Ni batteries.…”

Aqueous Magnesium Zinc Hybrid Battery: An Advanced High-Voltage and High-Energy MgMn2O4 Cathode

“…Among the above-mentioned RAMBs, those with zinc as the anode material have gained much interest due to the vast availability, low cost, nontoxicity, acceptable volumetric energy density, chemical affinity with aqueous electrolytes, and outstanding electrochemical properties of zinc. These properties suggest that zinc is an ideal negative electrode material for RAMBs. , Furthermore, because zinc is inexpensive and highly reliable, RAMBs with zinc anodes are promising candidates for large-scale ESDs . Much research has been done to utilize several electrode materials as divalent zinc storage hubs. − However, RAMBs with superior electrodes that have high capacity, high voltage, and stable electrochemistry and employ zinc as the anode are still under investigation.…”