Atomic Engineering Catalyzed MnO₂ Electrolysis Kinetics for a Hybrid Aqueous Battery with High Power and Energy Density

Abstract

Research interests and achievements in zinc aqueous batteries, such as alkaline Zn//Mn, Zn//Ni/Co, Zn-air batteries and near-neutral Zn ion and hybrid ion batteries, have surged throughout the world due to their peculiarity of low-cost and high-safety. However, practical application of Zn-based secondary batteries is plagued by restrictive energy and power densities in which an inadequate output plateau voltage and sluggish kinetics are mutually accountable. Here, a novel paradigm high-rate and high-voltage Zn-Mn hybrid aqueous battery (HAB) is constructed with an expanded electrochemical stability window over 3.4 V that is affordable. As a proof of concept, we demonstrate catalyzed MnO 2 /Mn 2+ electrolysis kinetics in HAB via facile introduction of Ni 2+ into the electrolyte. Various spectra techniques are employed including, in situ synchrotron X-ray powder diffraction, ex situ X-ray absorption fine structure and electron energy loss spectrum, to reveal the reversible charge storage mechanism and origin of boosted rate-capability. Density functional theory calculations figure out enhanced active electron states and charge delocalization after This article is protected by copyright. All rights reserved.introducing strong electronegativity Ni. Simulations of reaction pathways confirm enhanced catalyzed electrolysis kinetics by the facilitated charge transfer at active O sites around Ni dopants. These findings significantly advance aqueous batteries a step closer toward practical low-cost application.

Controlling electrochemical growth of metallic zinc electrodes: Toward affordable rechargeable energy storage systems

“…Figure 4A compares the typical electrolyte systems for Zn batteries: aqueous, walt-in-salt, molten salt, organic, and polymeric electrolytes. While all these systems exhibit some favorable features, it is clear that the aqueous electrolytes (89) appear as the most desirable option for its high operation current density (≈50 mA/cm 2 ) and low cost (<$1/kg) when paired with cost-effective cathodes such as MnO 2 (20,90). Compared with electrolytes that generate multiple inorganic/organic/polymeric products, aqueous Zn electrolytes have a relatively simple chemistry as delineated in Fig.…”

Opportunities of Aqueous Manganese‐Based Batteries with Deposition and Stripping Chemistry

“…Recently, Qiao and coworkers [ 79,147 ] reported an aqueous electrolytic MnO 2 ‐Zn battery that was comprised of a Zn‐foam anode, a glass fiber separator, a carbon fiber cloth as the cathode substance and a mixture of ZnSO 4 with MnSO 4 aqueous electrolyte (Figure 4a). When charged at 2.2 V to a capacity of 2 mAh cm ‐2 , the MnO 2 ‐Zn battery is capable of delivering an initial discharge capacity of 1.3 mAh cm ‐2 , which gradually increased to 1.92 and 1.97 mAh cm ‐2 in the 10th and 100th cycle, respectively.…”

“…Recently, Qiao and coworkers reported an electrolyte decoupled MnO 2 ‐Zn battery with catalyzed Mn 2+ /MnO 2 electrolysis kinetics (discharge in 60 s, at 50 C) via facile introduction of trace amount of Ni 2+ into the electrolyte (Figure 4f). [ 147 ] The hybrid aqueous battery demonstrated an electrochemical stability window of over 3.4 V and flat discharge voltage of 2.44 V.…”

“…Recently, the Ni catalyzed Mn 2+ /MnO 2 electrolysis kinetics process was carefully explored by Qiao and coworkers with the help of synchrotron spectra techniques and DFT calculations. [ 147 ] The significant role of Ni introduction in powering electrolytic reactivity is proposed via enhanced active electron states, charge delocalization, and facilitated charge‐transfer around strong electronegativity Ni.…”

“…Previous successful integration of the renewable energy resources and the practical applications of the stored energy to power LED panel, cellphone, and vehicle model have demonstrated the significant potential of the Mn‐based batteries with the Mn 2+ /MnO 2 chemistry for large‐scale energy storage. [ 76,78,79,147 ]…”