Dendrite-free lithium deposition on conventional graphite anode by growth of defective carbon-nanotube for lithium-metal/ion hybrid batteries

Conventional graphite faces theoretical capacity limitation, and conventional cells using graphite should have a sufficient N/P ratio to avoid lithium plating on the surface of graphite. This lithium plating not only causes severe cell degradation due to its poor reversibility but also causes critical safety issues by penetrating the separator. In this study, we present defective carbon-nanotube-grown graphite that has a high affinity for lithium deposition for electrochemical lithiation. These lithiophilic defective carbon nanotubes can result in densely packed lithium deposition without any dendritic lithium plating, causing poor reversibility and fatal safety issues. We observed that the dense lithium deposition on the defective-carbon-nanotube grown graphite provides three times denser deposition and 13% improved initial coulombic efficiency than dendritic lithium deposition on pristine graphite. As a result, in a full-cell evaluation, the lithiophilic defective carbon growth graphite showed excellent cycle stability (83.7%) over 300 cycles even with a reverse designed N/P ratio (0.8), which can increase the energy density by reducing the amount of anode and introducing lithium metal deposition on the anode surface.