posted on 2023-12-11, 16:04authored byAndrew M. Ullman, Xiaomin Tang, Xi Chelsea Chen
The
use of metal–organic frameworks (MOFs) in hybrid electrolytes
for lithium (Li) metal batteries has grown in prominence in recent
years, primarily due to the chemical tunability of the MOF’s
pore structures, which can directly influence Li–ion transport
properties. The most attractive form factor for a MOF electrolyte
is a thin, flexible membrane, which requires the application of pressure
to increase the contact between the MOF particles. Herein, a systematic
study of the influence of pressure on the properties of MOF-808-based
membranes is presented. It is shown that when a dry, roll-pressed
membrane is subjected to pressure ≥120 MPa, a total loss of
crystallinity and a significant loss of porosity is observed. Alternatively,
a slurry-cast membrane, compressed under controlled pressures, can
maintain crystallinity and porosity while decreasing the interparticle
void space. Interesting, the conductivity of the membranes infiltrated
with liquid electrolyte is not greatly affected by the pressure applied,
though ultimately it is shown that for cycling with Li metal, compressed
membranes with compact particles are preferred. This study highlights
the critical importance of controlling the pressure applied to MOF-based
membranes during fabrication and during cell assembly and lays out
the foundation for further investigation of how to optimize membrane
fabrication for hybrid electrolytes that use MOFs as the dominate
component.