Sodium Batteries: A Review on Sodium-Sulfur and Sodium-Air Batteries

Abstract

Lithium-ion batteries are currently used for various applications since they are lightweight, stable, and flexible. With the increased demand for portable electronics and electric vehicles, it has become necessary to develop newer, smaller, and lighter batteries with increased cycle life, high energy density, and overall better battery performance. Since the sources of lithium are limited and also because of the high cost of the metal, it is necessary to find alternatives. Sodium batteries have shown great potential, and hence several researchers are working on improving the battery performance of the various sodium batteries. This paper is a brief review of the current research in sodium-sulfur and sodium-air batteries.

Recent Advances in Emerging Non‐Lithium Metal–Sulfur Batteries: A Review

“…Thus, various carbonaceous matrices (e.g., graphene, carbon nanotubes (CNTs)), MXenes, and conductive polymers have been used to construct sulfur composites for high-performance sulfur cathodes. [43][44][45] (ii) Severe volume changes in sulfur during the charge/ discharge cycles. The mass density of elemental sulfur is ≈2.07 g cm −3 , while the generated polysulfides have a relatively lower density, for example, the mass density of sodium sulfide decreases to 1.86 g cm −3 .…”

A Progress Report on Metal–Sulfur Batteries

“…Nonaqueous Na‐S and K‐S batteries also work under a similar mechanism as that for the Li–S battery. [ 58 ] Electrolytes of Na‐S and K‐S batteries are formulated by following the same idea of Li–S system, being prepared by dissolving either a sodium salt [ 59 ] or a potassium salt [ 60 ] in a single ether‐based solvent or a mixed solvent of ethers. The charge‐discharge of Na‐S and K‐S cells also involves the formation of polysulfide intermediates that are soluble in either‐based solvents.…”

Unveiling the physiochemical aspects of the matrix in improving sulfur-loading for room-temperature sodium–sulfur batteries

“…complicated, the intermediate reaction steps that occur during the reactions are presented below through a series of reactions (eqn (1)-( 4)). 34,36 S 8 + 2Na + + 2e À -Na 2 S 8 (solid-liquid transition; B2.20 V vs. Na/Na + )…”

“…The reduction of Na + ions occurs at the cathode, where sulfur gains electrons and combines with the sodium ions to produce a range of polysulfides (Na 2 S n ), ranging from long-chain (4 r n r 8) to short-chain polysulfides (1 r n r 4). 36 The dissolution and diffusion of sodium polysulfides upon the oxidation of Na 2 S x (x = 1) provide mediators for the redox reactions to enhance the insulating nature of the elemental sulfur (5 Â 10 À30 S cm À1 @25 1C) and Na 2 S. 35,37 Due to the high solubility of the reaction intermediates, they shuttle between the anode and cathode, leading to polysulfide shuttling. The shuttle effect for RT-Na/S is even more severe than that of the Li-S battery, and consequently large volume fluctuations (about 170%) occur, leading to the structural collapse of the cathode during repeated charge/discharge cycles.…”