Towards Li-Ion Batteries Operating at 80 °C: Ionic Liquid versus Conventional Liquid Electrolytes

Abstract

Li-ion battery (LIB) full cells comprised of TiO 2 -nanotube (TiO 2 -nt) and LiFePO 4 (LFP) electrodes and either a conventional organic solvent based liquid electrolyte or an ionic liquid based electrolyte have been cycled at 80 • C. While the cell containing the ionic liquid based electrolyte exhibited good capacity retention and rate capability during 100 cycles, rapid capacity fading was found for the corresponding cell with the organic electrolyte. Results obtained for TiO 2 -nt and LFP half-cells indicate an oxidative degradation of the organic electrolyte at 80 • C. In all, ionic liquid based electrolytes can be used to significantly improve the performance of LIBs operating at 80 • C.

Capacity Limiting Effects for Freestanding, Monolithic TiO2 Nanotube Electrodes with High Mass Loadings

“…Given that the additional plateau only is seen in the 0.2C cycling curves, it is reasonable to assume that the reorganization only takes place for a sufficiently high degree of lithiation. These results in Figure are incidentally, in good agreement with our previous findings, demonstrating the presence of a second lithiation plateau at about 1.6 V vs Li + /Li as well as a corresponding delithiation plateau for analogous 10 μm long TiO 2 nanotubes cycled at a rate of 0.2C at 80 °C in 1 M LiTFSI in propylene carbonate. The fact that the extra lithiation and delithiation plateaus were very clearly seen in the latter article supports the hypothesis that an activation-controlled reorganization takes place at a sufficiently high degree of lithiation and that this facilitates further lithiation of the TiO 2 nanotubes.…”

“…30,33 As mentioned above, the lithiation rate has been assumed to be limited by the increasing Coulombic repulsion between the lithium ions and the slow lithium ion diffusion in the highly lithiated phase. 22,30,31 During and after the phase transformation, the redox reaction should still be TiO 2 + xe − + xLi + = Li x TiO 2 since the gravimetric capacities reached in the previous paper 28 only were about 150 mAh g −1 , which correspond to x ∼ 0.45. The latter value is in very good agreement with the corresponding result for the 4.5 μm nanotube electrode in Figure 2c, indicating a gravimetric capacity of about 150 mAh g −1 .…”

Poly(Ionic Liquid)s-in-Salt Electrolytes with Co-coordination-Assisted Lithium-Ion Transport for Safe Batteries

“…These performances also highlight the practical applications of polyIL-insalt electrolyte in high temperature batteries, which is a strategy to greatly simplify the battery system and improve energy efficiency for EVs. 60,61 Ongoing full cell testing, including with higher voltage cathode materials, is underway to determine the full potential of these electrolytes.…”

UV-Cured Poly(Siloxane-Urethane)-Based Polymer Composite Materials for Lithium Ion Batteries—The Effect of Modification with Ionic Liquids

“…A conductivity mechanism in lithium ion batteries containing both lithium salts and ILs as electrolytes was described in [51]. More recently, a comparison of electrochemical properties of lithium ion batteries containing ILs and conventional solvents was made [52]. The cell containing IL exhibited good capacity retention and rate capability during 100 cycles, while rapid capacity fading was found for the corresponding cell with the organic electrolyte.…”