Magnetic Field-Driven Ion Selectivity Boosts LiF-Rich SEI Formation for Enhanced Lithium Metal Battery Performance Across Temperatures

Lithium metal anodes are considered highly promising
electrode
materials due to their exceptional theoretical capacity and low reduction
potential. However, their path to large-scale commercialization has
been obstructed by significant challenges such as uncontrolled volume
expansion, severe side reactions, and dendrite formation. To tackle
these issues, our study introduces a covalent modification of separators
using tannic acid (TA) and Co2+, coupled with the application
of an external magnetic field. This innovative approach promotes the
adsorption of CO32– ions while inhibiting
the uptake of F– ions on the TA-Co/PP separators,
leading to the formation of a LiF-rich solid electrolyte interface
on the anode surface. Such modifications significantly enhance the
electrochemical performance of lithium metal batteries. Remarkably,
with the aid of the magnetic field, batteries featuring these modified
separators maintained a Coulombic efficiency of 90% over 650 cycles
at 1 mA cm–2. Additionally, under challenging conditions
at 60 °C and 4 mA cm–2, the polarization voltage
of Li symmetric cells utilizing TA-Co/PP separators is maintained
at just 20 mV. This successful demonstration underlines the potential
of our method to catalyze the broader adoption and commercialization
of lithium metal batteries across varied temperature spectra.