High-Rate NMC Cathodes Achieved with Carbon Nanotube Additive
Through a collaborative effort, the Dillon Group at NREL and the Whittingham Group at SUNY -Binghamton have enhanced the conductivity of NMC cathodes to improve their rate capability in Li-ion batteries. These layered cathodes usually suffer from poor electrical conductivity and capacity fade at high charge/discharge rates. To mitigate these problems, the researchers have incorporated single-wall carbon nanotubes (SWNTs) into the NMC cathodes (LiNi0.4Mn0.4Co0.2O2). The resultant composite cathodes exhibit stable high-rate capacities, ~130 mAh/g at 5C and nearly 120 mAh/g at 10C for over 500 cycles, which are significantly higher than those achieved with conventional NMC cathodes.
- Figure 1. a) SEM image of NMC cathode with 5 wt.% carbon nanotube loading, revealing that the particles are interconnected with well-dispersed carbon nanotubes. b) TEM image of the composite electrode showing that the carbon nanotubes seamlessly stick on the NMC particle surface. c) Comparison of conventional NMC cathode and NMC cathode with carbon nanotubes (NMCCNT) for 100 cycles while varying from low to high rates and then returning to low rate.