Free-standing ultrathick LiMn2O4@single-wall carbon nanotubes electrode with high areal capacity

Abstract

The ever-increasing demands for advanced lithium-ion batteries with high energy density have greatly stimulated the pursuit of thick electrodes with high active material loading. However, it is not feasible to prepare thick electrodes with traditional coating methods due to mechanical instability. Herein, using single-wall carbon nanotubes (SWCNT) as conductive carbon and binder, free-standing LiMn2O4 thick electrodes (F-LMO) with ultrahigh-mass loading up to ∼190 mg cm−2 were prepared by vacuum filtration combined with freeze-drying. The thick electrodes with ∼30 mg cm−2 mass loading achieved a high specific capacity of 106.7 mAh g−1 with a good capacity retention of 94% over 50 cycles at 0.5 C, which was superior to the traditional coating electrodes (∼20 mg cm−2) of 99.3 mAh g−1 with 95% because of the enhanced electronic conductivity originated from SWCNT. In addition, the high active material ratio of 97.5 wt%, near-theoretical reversible capacity, and high mass loading gave ultrathick F-LMO electrodes (600 μm) of ∼190 mg cm−2 with a remarkable areal capacity of 20 mAh cm−2. Moreover, the concentration polarization that occurred in the thick F-LMO electrodes under high current density was discussed via electrochemical stimulation.