Fast-charging
lithium-ion batteries (LIBs) have been severely hampered
by the slow development of their electrolytes. Herein, we demonstrate
that the size effect of solvent sheath would pose a great effect on
the fast-charging performance of LIBs. Three similar ethers, including
diethyl ether (DEE), dipropyl ether (DPE), and dibutyl ether (DBE),
were mixed with 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl
ether (TTE) and lithium bis(fluorosulfonyl)imide (1 M) to form an
electrolyte for fast-charging LIBs, respectively. The results showed
that it is more difficult to form ternary graphite intercalation compounds
(GICs) in the electrolyte with a larger solvation sheath. The DEE
electrolyte can form stable GICs and generate an inner LiF-rich solid
electrolyte interphase (SEI), lowering the diffusion barrier of Li+. Therefore, the graphite anode powered by the DEE electrolyte
can maintain a capacity of 190 mAh g–1 at 4 C after
500 cycles. This kind of size effect of solvation sheath is also applicable
to lithium metal batteries.