Solvated-ion intercalation or co-intercalation
reactions make graphite
a versatile anode for Na-ion chemistry and beyond. This alternate
intercalation mechanism could overcome the difficulties faced by conventional
intercalation reactions with graphite. The proper choice of the solvent
molecule could co-intercalate Na-, Li-, and K-ions with high capacity
and power density values, which are tailor-made for metal-ion capacitor
(MIC, M = Li, Na, and K) applications. This review summarizes significant
advances in co-intercalation chemistry, research progress in MICs
with a graphite anode, and activated carbon cathodes in glyme family
solutions. Also, we compare the advantages and challenges of MICs
with the co-intercalation-based mechanism in place of conventional
graphite anodes with bare-ion intercalation. The progress indicates
high-performance hybrid-ion capacitors with high power capability
and fast reaction kinetics. At the same time, it is essential to find
methods to improve the energy-storage capability of such MICs to realize
their commercial reality.