Electrochemical Performance of Carbon Modified LiNiPO₄ as Li-Ion Battery Cathode: A Combined Experimental and Theoretical Study

Abstract

This study demonstrates the synthesis of olivine LiNiPO 4 and carbon modified LiNiPO 4 (LNP/C-composites) cathode materials for use in lithium-ion batteries (LIBs) synthesized via non aqueous sol-gel process. The LNP/C-composites were fabricated through high energy ball-milling of LiNiPO 4 with different weight ratios of conductive carbon black. The electrochemical performance of LiNiPO 4 has been considerably improved by modifying the material with conductive carbon black which enhanced cathode performance as thoroughly studied by electrochemical analysis. Discharge capacities of LNP/C-composite cathodes with 25 wt% carbon were 175 mAh g −1 , 150 mAh g −1 and 125 mAh g −1 with corresponding capacity retention of 82.7%, 84.1% and 82.2% after 100 cycles at 0.05C, 0.1C and 1C rates, respectively. High-temperature electrochemical impedance spectra correspond to decreased charge transfer resistance with increased electronic conductivity and minimum cell polarization for the LNP/C powders. Additionally, the inflow of lithium-ion flux in cathode particle was simulated by using phase-field modeling indicating the coexistence of Li-poor and Li-rich phases during charging and discharging processes. The findings are significant for the development of optimal battery electrode materials as the methodology and insights used are readily transferable to other ioninsertion based electrodes.

Electro-Oxidation of Ammonia over Copper Oxide Impregnated γ-Al2O3 Nanocatalysts

“…Also, the bandgap decreases with the increase of crystallite size due to the quantum confinement effect [80,81]. Furthermore, the conductive electrocatalysts let ample electrons speed up the electrochemical reactions [82,83]. Therefore, in general, the materials containing higher CuO contents give better AEO per-formance due to the rapid transfer of electrons from the conduction band.…”

Nickel-doped lanthanum cerate nanomaterials as highly active electrocatalysts

“…The decreasing trend of polarization resistance of the 3L-LCNiO-5-based cell with temperature rise is presented in Figure 5A and shows an increase in the ionic conduction of the composited device at higher temperatures (Nasir et al, 2020).…”

“…Activation energy (E a ) is a major barrier in solid-state devices, and electrocatalysts are required to lower its value by adopting an alternative energy conversion path. In the cathodic performance of the Ni-doped lanthanum cerates in the 3-L configuration, the activation energy was estimated from the temperaturedependent EIS data using the Arrhenius equation: ln σT ln σ o − Ea RT (4) The activation energy for ionic conduction was calculated for the composited devices from the slopes of the Arrhenius plots (-E a /R) (Nasir et al, 2020), as presented in Figure 5B, to be 2.99 eV for LCNiO-1, 1.76 eV for LCNiO-5, and 1.16 eV for LCNiO-9. Electrical bandgaps were calculated using conductivity measurements (electrical bandgap = 2E a ).…”

Phosphate Polyanion Materials as High-Voltage Lithium-Ion Battery Cathode: A Review

“…However, these efforts were insufficient, and a complete elimination of the cobalt element from the cathode materials was encouraged for the development of lost-cost and more sustainable lithium-ion batteries . Undoubtedly, phosphate-based polyanions meet the requirement of cobalt-free cathodes, with both LiMnPO 4 and LiNiPO 4 achieving similarly high working potentials as LiCoPO 4 , , with LiMnPO 4 offering an identical gravimetry specific capacity to LiFePO 4 and slightly higher than LiCoPO 4 …”

“…However, these efforts were insufficient, and a complete elimination of the cobalt element from the cathode materials was encouraged for the development of lost-cost and more sustainable lithium-ion batteries. 99 Undoubtedly, phosphate-based polyanions meet the requirement of cobalt-free cathodes, with both LiMnPO 4 and LiNiPO 4 achieving similarly high working potentials as LiCoPO 4 , 100,101 with LiMnPO 4 offering an identical gravimetry specific capacity to LiFePO 4 and slightly higher than LiCoPO 4 . 102 Recently, orthosilicate (Li 2 MSiO 4 ) counterparts had attracted tremendous attention given their capabilities to offer higher theoretical gravimetry specific capacities (>300 mAh• g −1 for LiFeSiO 4 ) and almost identical working potentials (3.1 V vs Li/Li + for LiFeSiO 4 ) as phosphate analogues.…”