posted on 2021-12-13, 17:33authored byJianghe Liu, Zijian Ye, Xingcheng Hu, Sultan Ahmed, Shenhua Song
The scarcity of Li along with its
uneven distribution in earth
has become a great challenge in the field of electrochemical energy
storage. Replacing Li with Na may address the above issues, as Na
and Li are very similar in electrochemical characteristics, and Na
is abundant in nature with low cost. Herein, the Na-ion conducting
gel polymer membranes comprising a 2-HEC/EMITf/NaTf system are synthesized
by employing the solution-casting method. The effects of NaTf salt
and EMITf ionic liquid on the electrical and electrochemical properties
of membranes are investigated. It is demonstrated that the salt is
dissolved in the polymer matrix, thereby raising its ionic conductivity
(IC), which is further raised by ionic liquid incorporation. The optimized
membrane (2-HEC:EMITf:NaTf = 1:0.6:0.15 in mass, named as GPE/Na-3)
exhibits a high room-temperature IC of 1.11× 10–3 S cm–1 along with a wide electrochemical stability
window of 4.8 V. The membrane also displays sound tensile strength
and breaking strain (4.5 MPa and 94.4%, respectively). As the electrolyte,
the optimized membrane is combined with graphene electrodes to fabricate
a supercapacitor. The supercapacitor presents a high capacitive behavior
with an appealing cyclic stability. As evident from the above performance,
it is believed that the Na-ion conducting gel polymer membrane possesses
potential applications in future Na-ion energy storage devices.