Abstract:
An old coconut shell as a green biomass was known as a potential carbon materials for rGO and
cost effectiveness. The objective of this study is synthesizing an rGO – like carbon (C) compound
from coconut shells and inserting into LiFePO4 (LFP), as Li-ion battery cathode. Thus, an
LFP/rGO nanocomposite was successfully fabricated using an unconventional approach which is
the combination of the sol-gel technique and mechanical ultracentrifugation. LiFePO4 precursors
were prepared from commercial starting materials, using the sol-gel technique, and the
composites’ carbon weight content was varied between 15% and 30%. This process was
subsequently followed by evaluating the microstructural characteristics and electrochemical
properties as cathode for the Li-ion batteries. The results showed a high tendency of achieving
maximum efficiency with merged LFP and rGO, although LFP molecules appear scattered but are
firmly attached to each rGO structure, acting as a "bridge" between the surrounding particles. This
reduced graphene oxide (rGO) link is relatively effective in limiting LFP grain growth as well as
expanding the surface area, leading to a declined Li-ion diffusion rate. Consequently, the bridge
presence also demonstrated a significant effect by enhancing the conductivity, electrical capacity
and performance of the LFP/rGO cycle than pure LFP. Furthermore, the percentage ratio of the
synthesized LFP/rGO cathode (85:15), attained higher cycle capacity, compared to 70:30 on the
level of 0.1 C, with specific discharging average of 128.03 mAhg-1
and retention capacity of
97.75% after 50 cycles, at room temperature and a rate of 0.1 C.
Keywords: reduced graphene oxide (rGO), LFP (LiFePO4), LFP/rGO, nanocomposites, and mechanical ultracentrifugation method.
