Niobium oxides are an emerging class of anode materials
for use
in high-power lithium-ion batteries. Galvanostatic cycling and electrochemical
impedance spectroscopy (EIS) were used in this study to investigate
the influence of electrode porosity, electrode mass ratio, and cycling
rate on the capacity, cycle life, and ionic conductivity of Li-ion
battery cells based on a modified micron-sized MoNb
12
O
33
(MNO) anode powder. Both electrode and cell designs were
found to have a significant impact on the rate performance and cycle
life of Li-ion half- and full cells. A higher specific capacity, improved
rate performance, and a longer cycle life were obtained in both anode
and cathode half-cells by lowering the electrode porosity through
calendaring. MNO/Li half-coin cells displayed excellent cyclability,
reaching 80% state of health (SOH) after 600 cycles at C/2 charge
and 1C discharge. MNO/NMC622 full-coin cells displayed a high capacity
of 179 mAh g
–1
at 100 mA g
–1
(0.5
mA cm
–2
) and excellent cyclability at 25 °C,
reaching 70% SOH after over 1000 cycles at 1 mA cm
–2
after optimizing their N/P ratio. Excellent cyclability was obtained
at both 1C/1C and fast 2C/2C cycling, reaching 80% SOH after 700 and
470 cycles, respectively. Full-coin and small pouch cells had outstanding
rate performance as they could be charged from 0 to 84% capacity in
less than 5 min at 10 mA cm
–2
and to 70% SOC in
120 s at 20 mA cm
–2
.
The influence of diverse types of dispersing agents on the stability of aqueous boron carbide suspensions has been investigated. The best dispersants for aqueous B4C suspensions could not be accurately determined from zeta potential and settling experiments. Rheological measurements on concentrated slurries enabled identification of the optimal concentration of each dispersant and showed that PEI cationic polyelectrolytes were most effective.
Wadsley-Roth niobates show promise as anode materials for high-power lithium-ion batteries. This study presents a comprehensive investigation into the kinetics and thermodynamics of Li-ion transport in doped and carbon-coated micron-sized MoNb12O33 (MNO) electrodes, optimizing its performance in high-power cells alongside a LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode. The electrodes and cells were designed with an areal capacity of 1.2 ± 0.2 mAh cm2, 90 wt% active material, and a negative-to-positive capacity ratio of ~1.2. Galvanostatic intermittent techniques and potentiostatic electrochemical impedance spectroscopy (EIS) were employed to elucidate kinetic and thermodynamic electrochemical parameters. MNO exhibited an exchange current density of ~0.012-0.021 mA cm-2 and high lithium diffusion coefficients of ~10-9 cm2 s-1 at 50% state of charge (SOC) and 25°C. Lithiation and delithiation rate tests in MNO//Li and NMC622//MNO cell configurations at 15°C and 0°C highlighted the exceptional rate performance. Rapid charging of full cells was achieved at all tested temperatures, with charging times of 3 minutes to 75% state of charge at 25°C, 6 minutes at 15°C, and 30 minutes at 0°C. Notably, a 6-minute charge (10C rate) at 0°C still provided 50% of the initial capacity. EIS at various SOC levels indicated the formation of an unstable or reversible solid electrolyte interphase (SEI) layer on the MNO anode at 70-100% SOC. This research provides a valuable parameter set for the development of physics-based models and establishes a solid foundation for advancing the application of MoNb12O33 anode materials in high-power lithium-ion batteries, with potential implications for the broader field of energy storage technologies.
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