A KMnO₄-Generated Colloidal Electrolyte for Redox Mediation and Anode Protection in a Li–Air Battery

Abstract

The rechargeable lithium–oxygen (Li–O2) battery has the highest theoretical specific energy density of any rechargeable batteries and could transform energy storage systems if a practical device could be attained. However, among numerous challenges, which are all interconnected, are polarization due to sluggish kinetics, low cycle life, small capacity, and slow rates. In this study, we report on use of KMnO4 to generate a colloidal electrolyte made up of MnO2 nanoparticles. The resulting electrolyte provides a redox mediator for reducing the charge potential and lithium anode protection to increase cycle life. This electrolyte in combination with a stable binary transition metal dichalcogenide alloy, Nb0.5Ta0.5S2, as the cathode enables the operation of a Li–O2 battery at a current density of 1 mA·cm–2 and specific capacity ranging from 1000 to 10 000 mA·h·g–1 (corresponding to 0.1–1 mA·h·cm–2) in a dry air environment with a cycle life of up to 150. This colloidal electrolyte provides a robust approach for advancing Li–air batteries.

Fast Charge‐Transfer Rates in Li‐CO2 Batteries with a Coupled Cation‐Electron Transfer Process

“…To prepare the nanoflakes (NFs) of materials, the synthesized samples were exfoliated in isopropyl alcohol (IPA) using probe sonication followed by a centrifugation process (Figure 1A(i)). [17,18,20,24] Figure 1 shows the characterization results for Sb 0.67 Bi 1.33 Te 3 and the results for Sb 0.67 Bi 1.33 S 3 are included in SI file (Figures S1A-C, Supporting Information). Scanning Electron Microscopy (SEM) images of Sb 0.67 Bi 1.33 Te 3 powder before and after exfoliation are presented in Figure 1A(ii),(iii), respectively, showing the flake morphology of the material.…”

“…One major issue with the Li‐CO 2 chemistry is that existing catalysts are too inefficient in practice, exhibiting: 1) either low catalytic activities for CO 2 RR/CO 2 ER in aprotic media such as noble and transition metal (e.g., Pt and Au nanoparticles (NPs)), [ 17,18 ] or 2) low structural stability at high current rates such as 2D materials (e.g., MoS 2 ). [ 19,20 ] Another issue is that unlike Li‐O 2 batteries, [ 21–23 ] in Li‐CO 2 batteries the liquid catalysts so called “redox mediator” are usually inactive for the decomposing of discharge products, i.e., Li 2 CO 3 and solid carbon. Thus, a novel catalytic system is yet to be developed for a reversible and long cycle‐life Li‐CO 2 battery operating at high current rates.…”

Effect of Redox Additive in Aqueous Electrolyte for Electrochemical Energy Storage Applications of A and B Site Ordered LaCaCoCrO6 Double Perovskite

“…Consequently, the specific capacitance of the electrode material increases with improved cycle stability. [69] By using Equation ( 9) and (10), the estimated values of energy density and power density at 2 A g À1 are 13.75 and 439.84 W kg À1 , respectively (Figure 8f ).…”

Progress and Complexities in Metal–Air Battery Technology

“…[ 13 ] Another recent novelty is the KMnO 4 ‐based colloidal particulate electrolyte in a Li–O 2 battery with a cathode made of a mixed transition metal dichalcogenide alloy, Nb 0.5 Ta 0.5 S. The cell demonstrated a specific capacity of 10 000 mAhg −1 at a current density of 1 mAcm −2 for 150 cycles. [ 14 ] The state‐of‐the‐artwork highlighted by Science consists of a lithium carbonate anode, cathode employing molybdenum disulfide, and ionic liquid electrolyte with dimethyl sulfoxide. [ 15 ] This Li–O 2 battery remained stable for up to 700 cycles when exposed to a synthetic air environment.…”