Electrochemical characterization with homopolymer of 2-propen-1-amine coating on artificial graphite/carbon/silicon composites as anode materials for lithium ion batteries

This study reports the coating of spherical artificial graphite/disordered carbon/silicon (AG/C/Si) with a homopolymer of 2-propen-1-amine (PAA) layer. Transmission electron microscopy (TEM) observations clearly showed that the surface of the particle was coated with an amorphous layer of PAA-coated AG/C/Si composites. The resulting PAA-coated AG/C/Si electrode structure did not destroy locally because of large volume change. For both charge and discharge at 0.1 C, the PAA-coated AG/C/Si yielded the first columbic efficiency of approximately 89.1% and the first irreversible capacity decreased from 95.1 to 55.0 mAh g−1. Moreover, the discharge capacity was 410.1 mAh g−1 after 50 cycles, and its capacity retention increased to 91.5%. The addition of PAA decreased the specific surface area (BET) of the AG/C/Si composites and reduced the direct contact between the anode electrode surface and the electrolyte. These results indicate that PAA-coated AG/C/Si composites have relatively lower electrochemical resistance and favorable cycling stability.

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► PAA-coated AG/C/Si electrode structure showed no local cracking for large volume changes.
► PAA coating on AG/C/Si composites prevented bare silicon from contacting the electrolyte, it formed stable SEI layers.
► PAA-coated AG/C/Si composites showed a relatively low SEI resistance.