posted on 2022-01-10, 16:05authored byZhuo Zhang, Liying Tian, Hongyu Zhang, Hai Xu, Panpan Dong, Yayun Zhang, Donghui Long
Solid-state
lithium batteries using solid composite polymer electrolytes
(CPEs) with great thermal and mechanical stabilities are believed
to be the next-generation advanced electrochemical devices, but they
suffer from low ionic conductivity at room temperature and a poor
interface between the electrode and the electrolyte. Herein, we present
a poly(ethylene oxide) (PEO)-based CPE allowing rapid Li+ migration enabled by coordinating the anions on the exposed metal
sites of a metal–organic framework (MOF). The CPE contains
MOF-74 fillers, a PEO matrix, and lithium bis(trifluoromethanesulfonyl)imide
(LiTFSI). Owing to the strong anchoring effect of MOF-74 fillers on
TFSI– verified by calculations and measurements,
the CPE exhibits a high ionic conductivity (5.5 × 10–5 S·cm–1 at 30 °C), a wide electrochemical
stability (4.8 V), and an improved Li+ transference number
(0.36). Besides, the adjusted local current density promotes the interfacial
stability against the Li anode in a Li symmetric battery, which performed
well at a current density of both 0.2 and 0.4 mA cm–2. With these advantages, the all-solid-sate LiFePO4 battery
fabricated exhibited stable cycling performances (161 mA h g–1 and maintained 152 mA h g–1 after 300 cycles at
0.5 C). This strategy gives fresh reference to the utilization of
different MOFs and polymers in building high-performance solid-state
lithium batteries.