Enhancing Ion Transport in Thick Li-ion Battery Electrodes by Pore Engineering
Author(s)
Kim, Doyoub
Advisor(s)
Editor(s)
Collections
Supplementary to:
Permanent Link
Abstract
The development of lithium-ion batteries (LIBs) has been the driving force behind the
use of mobile electronic devices and the enabler of electric vehicles (EVs) and most energy
storage systems (ESSs). Despite their relatively high energy and power densities, reliability
and cost efficiency, the current performance limitations of conventional LIB materials highlight
the need for further improvements. To achieve volumetric and gravimetric energy densities
beyond 600-700 Wh/L and 250 Wh/kg, increasing the areal capacity loading of the electrode
from 3-4 mAh/ cm2
to 5-7 mAh/cm2 while maintaining volumetric electrode capacity and fast
charge and discharge capabilities is critical, especially for the widespread adoption of electric
vehicles. However, thicker and denser electrodes with higher areal capacities and lower
porosity (<20%) can compromise ion transport, reduce rate performance and lower capacity
utilization, especially at fast C-rates, due to highly tortuous ion paths that impede ion transport
and introduce unwanted internal resistance.
To address the drawbacks of dense electrodes, our study investigated the tradeoff
between laser patterning material loss and electrochemical performance of commercially
produced thick and dense high-nickel NCA, graphite, and silicon-blended graphite anodes
using high-nickel NCA, graphite, and silicon-blended graphite electrodes with areal capacities
of 4.8 and 6 mAh/ cm2
and porosities of less than 20%. The study revealed that laser patterning
of straight, tapered channels in these electrodes decreased electrode tortuosity and accelerated
ion diffusion. This resulted in a substantial improvement in rate performance compared to
conventional thick electrodes. Despite these improvements, this approach typically resulted in
significant electrode material loss of 1 to 8% by weight, which reduced the volumetric capacity
of the electrodes, compromised energy density, and increased the overall cost of the battery.
In response to these challenges, an innovative, cost-effective one-step electrode
patterning method has been developed. This novel approach forms a hexagonal array of
channels in highly areal loading graphite anodes as part of an advanced electrode architecture
engineering process. Not only does it prevent active material loss, but it's also suitable for a
continuous, roll-to-roll process. Although these introduced channels represent a minimal
volume fraction, they significantly improve battery performance by accelerating electrolyte
infiltration and subsequently increasing battery rate performance.
Another alternative approach involving the use of aqueous processed electrodes with
inhomogeneous randomly distributed pores of different channel sizes was also explored. This
strategy not only addresses the kinetic limitations associated with thick, high-mass LIB battery
electrodes, but also responds to environmental and health concerns associated with the use of
N-methyl-2-pyrrolidone (NMP) in the battery industry. Despite the random distribution of
these channels, they significantly improve the overall performance of the battery by facilitating
ion transport
Sponsor
Date
2023-08-09
Extent
Resource Type
Text
Resource Subtype
Dissertation