CuV₂S₄: A High Rate Capacity and Stable Anode Material for Sodium Ion Batteries

Abstract

The ternary compound CuVS exhibits an excellent performance as anode material for sodium ion batteries with a high reversible capacity of 580 mAh g at 0.7 A g after 300 cycles. A Coulombic efficiency of ≈99% is achieved after the third cycle. Increase of the C-rate leads to a drop of the capacity, but a full recovery is observed after switching back to the initial C-rate. In the early stages of Na uptake first Cu is reduced and expelled from the electrode as nanocrystalline metallic Cu. An increase of the Na content leads to a full conversion of the material with nanocrystalline Cu particles and elemental V embedded in a NaS matrix. The formation of NaS is evidenced by Na MAS NMR spectra and X-ray powder diffraction. During the charge process the nanocrystalline Cu particles are retained, but no crystalline materials are formed. At later stages of cycling the reaction mechanism changes which is accompanied by the formation of copper(I) sulfide. The presence of nanocrystalline metallic Cu and/or CuS improves the electrical conductivity, leading to superior cycling and rate capability.

Elucidation of the Sodium – Copper Extrusion Mechanism in CuCrS2: A High Capacity, Long‐Life Anode Material for Sodium‐Ion Batteries

“…In several publications it was reported that ether‐based electrolytes show a superior cycle life in LIBs and SIBs containing sulfide based materials, and therefore NaCF 3 SO 3 in DGM was chosen here . In order to improve the cycling stability, different cut‐off potentials were applied at a current density of 120 mA g −1 for the first and 600 mA g −1 for subsequent cycles (Figure ).…”

“…In several publications it was reported that ether-based electrolytes show a superior cycle life in LIBs and SIBs containing sulfide based materials, and therefore NaCF 3 SO 3 in DGM was chosen here. [47][48][49] In order to improve the cycling stability, different cut-off potentials were applied at a current density of 120 mA g À1 for the first and 600 mA g À1 for subsequent cycles (Figure 2). When cycled in the voltage range of 3-0.01 V, the capacity fades slowly from 520 to 445 mAh g À1 from the third to the 70 th cycle and followed by a quick capacity drop for subsequent cycles down to 121 mAh g À1 at cycle 100 (Figure 2a).…”

Pulverization‐Tolerance and Capacity Recovery of Copper Sulfide for High‐Performance Sodium Storage

“…As a promising alternative for LIBs, thus, sodium ion batteries (SIBs) have been suggested owing to natural abundance and low cost of sodium, and its similar chemical nature to lithium. [5,9,12] There have been numerous reports on conversion reaction materials that show the capacity recovery after its initial degradation, [13][14][15] which is counter-intuitive since conversion reaction typically induces pulverization, which translates directly into capacity degradation. [1][2][3][4][5][6][7] Unlike intercalation reaction, conversion and alloying reactions generally involve abrupt crystallographic changes and huge volume expansion rate over 100% leading to capacity degradation by active materials destruction.…”

“…[1][2][3][4][5][6][7] Unlike intercalation reaction, conversion and alloying reactions generally involve abrupt crystallographic changes and huge volume expansion rate over 100% leading to capacity degradation by active materials destruction. [5,9,12] There have been numerous reports on conversion reaction materials that show the capacity recovery after its initial degradation, [13][14][15] which is counter-intuitive since conversion reaction typically induces pulverization, which translates directly into capacity degradation. [5,9,12] There have been numerous reports on conversion reaction materials that show the capacity recovery after its initial degradation, [13][14][15] which is counter-intuitive since conversion reaction typically induces pulverization, which translates directly into capacity degradation.…”

Schwefel‐basierte Elektroden mit Mehrelektronenreaktionen für Raumtemperatur‐Natriumionenspeicherung

“…Diese Eigenschaften machen es zu einem vielversprechenden Anodenmaterial fürh ochleistungsfähige Na-Ionen-Batterien. B. CuV 2 S 4 , [31] FeV 2 S 4 [32] und Ni 3 Co 6 S 8 . Sie basiert auf der Nickelarsenidstruktur (NiAs) mit a = 3.67 , c = 5.04 , wobei die c-Schichten abwechselnd Fe 2+ -u nd S 2À -Ionen enthalten.…”