  Conductive metal-organic frameworks (c-MOFs) and ionic liquids (ILs) have
emerged as auspicious combinations for high-performance supercapacitors.
However, the nanoconfinement from c-MOFs and high viscosity of ILs slow down
the charging process. This hindrance can, however, be resolved by adding
solvent. Here, we performed constant-potential molecular simulations to
scrutinize the solvent impact on charge storage and charging dynamics of
MOF-IL-based supercapacitors. We find conditions for >100% enhancement in
capacity and ~6 times increase in charging speed. These improvements were
confirmed by synthesizing near-ideal c-MOFs and developing multiscale models
linking molecular simulations to electrochemical measurements. Fundamentally,
our findings elucidate that the solvent acts as an ionophobic agent to induce a
substantial enhancement in charge storage, and as an ion traffic police to
eliminate convoluted counterion and co-ion motion paths and create two distinct
ion transport highways to accelerate charging dynamics. This work paves the way
for the optimal design of MOF supercapacitors.
