Rational Design of Electrolyte Solvation Structures for Modulating 2e⁻/4e⁻ Transfer in Sodium–Air Batteries

Abstract

In sodium–air batteries (SABs), achieving the regulation of the electron transfer number during oxygen reduction reactions (ORRs) in the same electrolyte system remains a significant challenge. In this work, a promising strategy is proposed to dynamically modulate 2e−/4e− transfer in ORRs by regulating the electrolyte structures to realize the different performances of SABs. The 4e− ORR can be realized by decreasing the electrolyte concentration. The solvation sheath of Na+ at dilute concentrations consists mainly of water molecules that hinder the access of Na+ to the cathode surface due to the high solvation energies indicated by theoretical calculations, thereby impeding the 2e− reaction. In contrast, excess free water can easily access the cathode surface and trigger the 4e− ORR. The solvation energies of Na+ can be remarkably reduced by increasing the electrolyte concentration, forming a water‐in‐salt unit, in which the Na+ mainly coordinates with the bis(fluorosulfonyl)imide anion and can be easily released from the solvation sheath. Hence, the 2e− ORR is significantly promoted and becomes the dominant reaction. The SAB based on the 2e− reaction exhibits excellent energy density (15980 Wh kg−1) and good cycle performance (300 times), and the 4e− reaction exhibits excellent power density (12.09 mW cm−2).

P‐Orbital Bismuth Single‐Atom Catalyst for Highly Effective Oxygen Electroreduction in Quasi‐Solid Zinc‐Air Batteries

“…[5,6] The low reserves of noble metals force researchers to reduce the usage amount of metal during preparing ORR catalysts, meanwhile, to improve the loading of noble metals within catalysts and utilization efficiency for the rational utilization of resources. [7,8] Except rational utilization of noble metal catalysts (such as Pt/C), researchers are also committed to developing plentiful low-cost and non-noble metal catalysts with excellent ORR activity. [9] Massive researchers have found that non-noble metal catalysts based on 3d-shell transition metals as main active components are the mainstream of ORR catalysts on account of benefits such as low price, excellent electro-catalytical performances, easily regulated molecular structures, and coordination environments.…”

Recent advances in solid‐state metal–air batteries

“…In addition, theoretical simulation is also an effective means, such as first-principal calculation 152 or molecular dynamics simulation. 153 In sum, there is still a long way to go for the application of all-solid-state metal-air batteries. Significant research efforts are still required for the further development of solid-state metal-air batteries.…”

High‐Rate Performance of Fluorinated Carbon Material Doped by Phosphorus Species for Lithium‐Fluorinated Carbon Battery

“…Compared with some secondary batteries, such as all-solid-state batteries and metal-air batteries, Li/CF x battery has better performance for some internet of things devices and sensors in extreme temperature conditions. [5,6] Unfortunately, owing to the poor electronic conductivity of the fluorinated carbon (CF x ) material, the Li/CF x battery is suffering from a low-rate discharge limit and voltage delay. Such a voltage delay may add insult to injury, worsening the power capability exertion.…”