Improved Performance of VO_x‐Coated Li‐Rich NMC Electrodes

Abstract

A VOx coating of Li1.2Mn0.56Ni0.16Co0.08O2, made through a low‐temperature annealing process (350 °C), results in the formation of a protecting layer, which enables electrodes to be prepared with an aqueous binder, offering a significantly improved electrochemical performance. The comparison with uncoated electrodes demonstrates the significantly improved performance of VOx‐coated Li1.2Mn0.56Ni0.16Co0.08O2, which substantially outperforms the uncoated material by 30 mAh g−1 at moderate rates. The VOx coating is found to prevent the contact of Li1.2Mn0.56Ni0.16Co0.08O2 with water from the aqueous‐binder processing, preventing leaching of metal cations. Upon cell operation, the coating delays the transformation of the active layer material into the spinel phase, occurring at low voltages, thus delaying its typical capacity fade upon cycling. Finally, the coating contributes to the overall material capacity, while ensuring the lithium deintercalation and intercalation processes.

Effect of coatings on the green electrode processing and cycling behaviour of LiCoPO4

“…Although VO x is not a good electronic conductor, a very thin layer of VO x on the particle surface of Li 2 MnO 3 $LiMO 2 (M ¼ Ni, Mn, Co), also operating above 4.5 V, was shown to signicantly enhance the capacity and cycling performance. 17 As shown later in this manuscript, the carbon coating enhances signicantly the conductivity of LCP electrodes which, therefore, deliver higher capacities. However, such electrodes still suffer from signicant fading upon cycling, thus offering poor capacity retention.…”

Generation of Vanadium Oxide Quantum Dots with Distinct Fluorescence and Antibacterial Activity via a Room‐Temperature Agitation Strategy

“…Vanadium oxide (VO x ) nanomaterials including nanowires, nanoflakes, nanotubes, have been attracting great interest in nanozyme, high‐energy lithium batteries, environmental remediation catalysis, hydrogen storage, etc ,. due to their outstanding properties such as low toxicity, structural flexibility and distinctive redox behavior .…”

Role of Manganese in Lithium- and Manganese-Rich Layered Oxides Cathodes

“…6 Despite the great potential, the implementation of Li-rich NMC in practical Li-ion batteries is limited by the poor kinetics and reversibility and the large voltage decay upon cycling. To circumvent this issue, many synthesis efforts have been performed, 4,[7][8][11][12][13][14][15][16][17][18][19][20][21] however, understanding the problem from the structural/chemical point of view is still limited.…”

“…Some irreversible reactions occur as demonstrated by the disappearance of the voltage plateau at 4.4 V in the following discharge and the next cycles. 13,14 It has been proposed that, in the first charge, two reactions occur in series: (i) one involving the LiMO 2 component, i.e., the Ni 2+ /Ni 4+ and Co 3+ /Co 4+ redox reactions, while…”

“…S15g) strongly suggests formation of compounds with the oxygen expected to be released at the end of the voltage plateau in the uncoated material, but which seems suppressed by the VO x -coating. 14 In the following we continue to focus on the pre-edge absorption features which are less influenced by the chemical environment being more directly connected to the M valence and magnetic state. In Fig.…”