High C-rate capability at 10C is a key performance indicator
for
the commercialization of the next-generation high-charging lithium
microbattery. However, silicon (Si) anode satisfying the prerequisite
high specific capacity suffers from poor electron/ionic conductivity,
seriously limiting the 10C rate capability. Accordingly, we propose
the strategy of inserting highly conductive silver nanoparticles (AgNPs)
as an interlayer between two RF-sputtered amorphous Si thin films
to form an Si/Ag/Si multilayered anode, with the density and spatial
distribution of the AgNPs well-controlled by thermal evaporation.
This strategy is exclusively beneficial to scale up film thickness
for higher capacity. Without AgNPs, the 10C rate performance of the
double-layer Si (D_Si) is worse than the single layer (S_Si) in the
same total thickness, suggesting the adverse effect of the interface.
However, this situation is progressively improved with the AgNPs density
incorporated at the interface, where the densest AgNPs anode (D_SiAg3)
demonstrated a noticeable improvement reaching 1250 mAh/g at 10 C
with a 46% capacity retention rate. By scaling up to triple layers,
T_SiAg3 performed the superior 10C rate capability to T_Si, testifying
to the scalable potential of the unique design for boosting high-power
batteries. Finally, with electrochemical impedance spectroscopy results,
a possible mechanism to explain the enhancement in rate capability
is subject to where Li-ion diffusion is accelerated by the charge-induced
electric field condensing around the AgNPs. This design for a multilayered
nanocomposite can contribute to the design and fabrication of high-charging
batteries and battery-on-chip.
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