Gradient Designs for Efficient Sodium Batteries

Abstract

Sodium batteries have received extensive attention as low-cost and high-performance devices for next-generation energy storage. There are, however, significant challenges toward practical deployment such as poor electrode integrity and durability. These are primarily caused by severe stress and strain upon electrochemical (de)­sodiation, as a result of large Na ions. Gradient designs, either chemically or structurally, have proven uniquely capable of mitigating these issues. Despite the early stage of development, gradient designs have enabled significant progress in sodium batteries. In this Focus Review, we highlight the principles and features of gradient designs and their successful applications in sodium batteries. A particular focus is placed on the understanding of how the gradient idea could address some critical issues such as stress dissipation, structure stabilization, charge and mass transport, and dendrite suppression. The remaining challenges and future research directions related to gradients in sodium batteries are also discussed.

Inhibition of the P3–O3 phase transition via local symmetry tuning in P3-type layered cathodes for ultra-stable sodium storage

“…Sodium ion batteries (SIBs) are an emerging secondary battery technology for grid-scale energy storage owing to the abundance and low cost of Na sources. [1][2][3][4] To meet the ever-growing demand for sodium electricity booming, developing suitable cathodes with high reversibility and rate capability is one of the particularly critical aspects. Among numerous cathode candidates, layered oxides Na x TMO 2 (TM = 3d transition metals) are attractive for their stable structure, high average working voltage and facile processability.…”

Engineering CSFe Bond Confinement Effect to Stabilize Metallic‐Phase Sulfide for High Power Density Sodium‐Ion Batteries

“…The two peaks at 164.9 and 163.8 eV positions of NHCFs-S-FeS 2 can also be attributed to C-S-Fe 2p 1/2 and C-S-Fe 2p 3/2 , respectively. Finally, the last two peaks approximately at 169.6 and 168.5 eV of all composites indicate the presence of SO 4 2− , which stems from partially oxidized sulfur species on the material surface. [45] Whilst, the C 1s spectra in NHCFs-S-Fe 7 S 8 , NHCFs-S-FeS 2 , and NHCFs-CS 2 could be categorized into three obvious peaks close located at 284.8, 286.1, and 289.1 eV, consistent with CC/CC, CS, and OCO bonds, respectively (Figure S9b-d), [44,47] demonstrating the existence of the CS bonds between the carbon skeleton and iron sulfide particles.…”

“…

Sodium-ion batteries (SIBs) are regarded as the most cost-effective substitute for largescale power storage because sodium exhibits similar electrochemical properties and is far more abundant than lithium (Na: 23.0 wt.% vs Li: 0.017 wt.%). [1][2][3][4] Hence, SIBs have been extensively researched in both academic circles and the industrial community recently. [5][6][7] Excellent rate characteristics and high reversible capacity have been proven for high-power 26650-type columniform SIBs in the early commercialization stage.

…”

Unconventional Designs for Functional Sodium‐Sulfur Batteries

“…This conversion reaction of S leads to a large theoretical capacity of 1672 mAh g −1 , and the stripping and plating of Na metal give a high capacity of 1166 mAh g −1 . [6,7] The combination of these two highcapacity electrode materials leads to a high specific energy of 1274 Wh kg −1 (based on the product of Na 2 S), which is much greater than that of Li-ion batteries. Current Li-ion batteries in electronics need to recharge at least once each day.…”