Performance of NASICON Symmetric Cell with Ionic Liquid Electrolyte

Abstract

To improve the thermal stability of lithium- and sodium-ion batteries, the room-temperature molten salts LiBF4 /1-ethyl-3-methyl imidazolium tetrafluoroborate (EMIBF4) and NaBF4/EMIBF4 were used as ionic liquid (IL) electrolytes instead of flammable carbonate-type organic electrolyte solvents. To avoid cathodic decomposition of the IL electrolytes, a symmetric cell configuration with Na Superionic CONductor (NASICON)-type normalA3normalV2(PO4)3 (where A is Li or Na) as both cathode and anode was tried in a coin-type cell (type 2320). As a result, both the polyanionic-based Li3normalV2(PO4)3 (LVP) as well as Na3normalV2(PO4)3 (NVP) symmetric cells using organic electrolytes were found to operate as secondary batteries and exhibited satisfactory electrochemical performances. The substitution of the organic electrolytes by the appropriate IL electrolytes in both cases resulted in the reduction in the first discharge capacities. However, the IL-based cells revealed better cyclability and a more stable behavior at elevated temperatures. The obtained electrochemical behavior of the symmetric cells was confirmed by the complex impedance measurements at 25 and 80°C . In addition, the thermal stability of LVP and NVP with the IL electrolytes was also examined.

Effect of Iron Substitution in the Electrochemical Performance of Na3V2(PO4)3as Cathode for Na-Ion Batteries

“…A similar feature is commonly detected in Li 3 V 2 (PO 4 ) 3 , while a 4 V signal is rarely reported for the sodium compound. 22 It was ascribed to the extraction of the third sodium atom parallel to the oxidation of V 4+ to V 5+ . The significant overvoltage would involve the consumption of a high energy for the removal of the last alkali atom from the NASICON 3D framework.…”

“…These authors ascribed this plateau to the extraction of the third alkali atom ascribable to the V 5+ /V 4+ redox couple, similarly to the Li 3 V 2 (PO 4 ) 3 case. 22 Quasi-equilibrium curves were recorded for the first cycles by the PITT method (Figure 7). The potential versus composition plot (dark line) reproduces very well the features observed in Figure 4.…”

Electrode Materials for Sodium-Ion Batteries: Considerations on Crystal Structures and Sodium Storage Mechanisms

“…Carbon-coated Na 3 V 2 (PO 4 ) 3 was investigated and showed promising performance. Taking advantage of the large voltage difference between the plateaux, a symmetric cell using Na 3 V 2 (PO 4 ) 3 as both negative and positive electrodes was designed with an ionic liquid electrolyte [84]. The symmetric cell reversibly delivered 64 mA h g −1…”

Aromatic porous-honeycomb electrodes for a sodium-organic energy storage device

“…There is an urgent need for alternative energy storage devices with a performance comparable to, or better than rechargeable lithium batteries. One possible approach is to use sodium as an alternative charge carrier [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] to lithium, as the cost of sodium carbonate (Na 2 CO 3 ), for example, is only 3% of Li 2 CO 3 (ref. 5).…”