Anode

Graphite Anode

Graphite

Engineering microstructure and defects to enhance electrochemical performance in graphite anodes Researchers at North Carolina State University and Oak Ridge National Laboratory used nanosecond pulsed laser annealing (PLA) to alter the structure of graphite and improve electrochemical performance. Carbon vacancies created during the PLA process provide sites for Li+ during charging, while increasing the current density that can be achieved during discharge by 20 percent. In addition, steps and grooves generated on the surface of the graphite improve Li+ diffusion transport. Inactive or ineffective disordered carbon and PVDF binder that may otherwise hinder lithium transport is also removed from the graphite surfaces. However, PLA must be optimized; if the vacancy concentration is too high, crowding of Li+ can cause electron trapping and result in lithium plating.

Figure A-B: AFM images of a (A) reference graphite without PLA treatment and (B) optimised PLA treatment graphite sample. Figure C shows a reference sample (S0) compared to under-annealed and unoptimised (S1), optimised (S2), and over-annealed and unoptimised (S3) PLA-treated graphite. Academia | P. 216 Source: N. Khosla, J. Narayan, R. Narayan, X Sun, M P Paranthaman

Pulsed laser annealing (PLA) alters graphite structure for increased rate capability in lithium ion cells, owing to increased vacancies within the structure and surface steps and grooves.

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