Better Cycling Performances of Bulk Sb in Na-Ion Batteries Compared to Li-Ion Systems: An Unexpected Electrochemical Mechanism

Abstract

Pure micrometric antimony can be successfully used as negative electrode material in Na-ion batteries, sustaining a capacity close to 600 mAh g(-1) at a high rate with a Coulombic efficiency of 99 over 160 cycles, an extremely high capacity compared to any other compound tested against both Li and Na. The reaction mechanism with Na does not simply go through the alloying mechanism observed for Li where the intermediate species are those expected from the phase diagram. In the case of Na, the intermediate phases are mostly amorphous and could not be precisely identified. Surprisingly, we evidenced that a competition takes place at the end of the discharge of the Sb/Na cell between the formation of the hexagonal and the cubic polymorphs of Na(3)Sb, the last being described in the literature as unstable at atmospheric pressure and only synthesized under high pressure (1-9 GPa). In addition, fluoroethylene carbonate added to the electrolyte combined with an appropriate electrode formulation based on carboxymethyl cellulose, carbon black, and vapor ground carbon fibers seems to be determinant in the excellent performances of this material.

A Safer Sodium‐Ion Battery Based on Nonflammable Organic Phosphate Electrolyte

“…Another pair of the weak peaks around 0 V should be attributed to the intercalation/deintercalation reaction of Na in carbon. At the subsequent scans, except for the disappearance of the irreversible current peak at ≈1.0 V due to the formation of SEI film, the CV curves show an additional reduction peaks at 0.63 V, which is apparently attributed to the first‐step alloying reaction of Sb with Na 36, 62, 63. This phenomenon suggests an activation process occurring during first discharge to accelerate the kinetics of the alloying reaction.…”

Assessing Si-based anodes for Ca-ion batteries: Electrochemical decalciation of CaSi2

“…Alloying electrodes have shown to exhibit large capacities with lithium [5] and are also starting to be investigated with sodium and magnesium [6,7]. A recent publication reported on a tin anode for a Caion system utilizing manganese hexacianoferrate as the cathode, although no detailed characterization was provided on the tin electrode reaction mechanism [8].…”

MoS2/Graphene Composite Paper for Sodium-Ion Battery Electrodes

“…8 To this end, researchers have proposed a number of high-capacity sodium host materials (negative electrode) involving either carbon or group IVA and VA elements that form intermetallic compounds with Na. [9][10][11][12][13] The alloying compounds demonstrate high first cycle Na-storage capacities, such as Na 15 Sn 4 (847 mAhg -1 ), Na 15 Pb 4 (485 mAhg -1 ), Na 3 Sb (600 mAhg -1 ) and Na 3 P (2560 mAhg -1 ), respectively. However, this comes at the cost of very high volume change upon Na-insertion (as much as 500 % in some cases), resulting in formation of internal cracks, loss of electrical contact, and eventual failure of the electrode (particularly for thick electrodes).…”