Electrode Engineering with CNTs to Enhance the Electrochemical Performance of LiNi_0.6Co_0.2Mn_0.2O₂ Cathodes with Commercial Level Design Parameters

Abstract

Electrode engineering is considered an essential step toward fabricating advanced Li‐ion batteries (LIBs). Conducting agents play a critical role in determining both the electron conduction and Li‐ion transport in electrodes and thus in enhancing battery performance. Here, we report the effect of carbon nanotube (CNT) addition on the electrochemical properties of LiNi0.6Co0.2Mn0.2O2 (NCM622) cathodes. By varying the CNT content from 0 to 2 wt% in the total weight percentage (2 wt%) of conducting agents containing carbon black, the rate capability and cycling performance are examined. The limiting factors affecting the electrochemical performance are probed by using electrochemical impedance spectroscopy and pulse polarization measurements. The results show that as the CNT content increases, the electrical conductivity of the electrode decreases and the porosity increases. The addition of 1 wt% CNT gives rise to the best rate and cycling properties for the NCM622 electrodes. The pulse measurements reveal that the CNT addition mitigates the concentration polarization upon charging/discharging at high current rates owing to the evolved micrometer‐scale pores in the electrodes, thereby leading to better rate capability. The post‐mortem analysis on the electrodes discharged at a high current rate by time‐of‐flight secondary ion mass spectroscopy mapping show that the CNT addition allows facile Li‐ion transport from the electrolyte side into the NCM lattice, even in the vicinity of the bottom region (current collector side), which strongly corroborates the pulse polarization results. These findings suggest that the use of CNTs as a conducting agent is effective in improving the electrochemical performance of Ni‐rich cathodes.

Enhancing the Electrochemical Properties of Nickel-Rich Cathode by Surface Coating with Defect-Rich Strontium Titanate

“…However, under 5C and 10C current rates, NCA-STOx maintained higher specific capacity than NCA suggesting that electrical conductivity becomes more significant under high rates. 36,37 Notably, STO-NCA (without NaBH 4 treatment) also demonstrates improved rate performance when the C-rate is ≥ 1C, which follows our previous research. 12 The reason could be that the coating layer suppressed severe side reactions triggered by high current density.…”

Enhancement of Li intercalation kinetics of LiFePO4 nanoparticles with mesoporous carbon

“…Typically, Li-ion redox materials offer substantial energy density in battery systems but suffer from poor rate performance due to the slow Li-ion extraction/intercalation reaction [4,5] . To address this issue, the incorporation of certain carbon materials, such as carbon nanotubes (CNTs) and conductive black, or the development of Li-ion cathode material/porous carbon composites has been widely employed to enhance electron transfer within the cathode [6][7][8][9][10] . However, these approaches have not directly improved Li-ion diffusion within the matrix of the cathode materials.…”

Analysis of Electrochemical Performance with Dispersion Degree of CNTs in Electrode According to Ultrasonication Process and Slurry Viscosity for Lithium-Ion Battery

“…These disadvantages make it unsuitable for batteries that require high power density, with the electron movement being a limiting factor at high C-rates. Therefore, research using carbon nanotubes (CNTs) with high aspect ratio and high crystallinity as a conductive material have been widely reported [ 13 , 14 , 15 , 16 ], but due to the high aggregation characteristics of CNTs during the electrode fabrication process, it is difficult to apply it effectively as a conductive material [ 17 , 18 , 19 ]. Therefore, focusing on finding an effective electrode fabrication process that combats this aggregation of CNTs will yield a significantly improved high current density performance for the cathode electrode.…”