Figure 5 Rate capabilities (a), charge-discharge curves at 2 C (b), and impedance curves (c) of the LFP electrodes with SCNT-S-1.4%, SCNT-S-0.7% and the undoped CNTs as conductive additive, fabricated with NMP as solvent. For LFP, 1 C correspond to 140 mAh g-1.
3.3.2 Water-based slurry
Compared to NMP, water is a cheaper and safer solvent. Replacing NMP by water in the electrode fabrications is promising to further reduce the cost of LIBs. Therefore, we further applied the as-prepared CNTs as aqueous conductive additives for LFP electrodes, using water rather than NMP as solvent in the electrode fabrication. As shown in Figure 6a, obvious CNT agglomerates are observed in the LFP electrode fabricated with the pristine CNTs aqueous slurry. Similar CNT agglomeration is also found in the LFP electrode with SCNT-M (Figure 6b). In contrast, evenly-distributed CNT networks without obvious agglomeration are found in the LFP electrodes using SCNT-S and SNCNTs aqueous slurries (Figure 6c and d). It is comprehensible since SNCNTs and SCNT-S have better hydrophility than SCNT-M and CNTs, thus leading to better dispersion in aqueous slurries.