Room temperature performance of 4 V aqueous hybrid supercapacitor using multi-layered lithium-doped carbon negative electrode

Abstract

Water-stable multi-layered lithium-doped carbon (LixC6) negative electrode using poly(ethylene oxide) (PEO)-lithium bis(trifluoromethansulfonyl)imide (LiTFSI) polymer electrolyte containing N-methyl-N-propylpiperidinium bis(trifluoromethansulfonyl)imide (PP13TFSI) ionic liquid was developed. Electrochemical properties at 60˚C of the aqueous hybrid supercapacitor using activated carbon positive electrode and a multi-layered LixC6 negative electrode (LixC6 | PEO-LiTFSI | LTAP) without PP13TFSI exhibited performance similar to that using Li anode (Li | PEO-LiTFSI | LTAP). A drastic decrease in ESR was achieved by the addition of PP13TFSI to PEO-LiTFSI, allowing room temperature operation. The ESR of the multi-layered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI at 25˚C was 801  cm 2 , which is 1/6 the value of the multi-layered Li negative electrode with PEO-LiTFSI (5014  cm 2). Charge/discharge test of the aqueous hybrid supercapacitor using multilayered LixC6 negative electrode with PEO-LiTFSI-PP13TFSI at 25˚C afforded specific capacity of 20.6 mAh (g-activated carbon) 1 with a working voltage of 2.7-3.7 V, and good long-term capability up to 3000 cycles. Furthermore, an aqueous hybrid supercapacitor consisting of a high capacitance RuO2 nanosheet positive electrode and multi-layered LiC6 negative electrode with PEO-LiTFSI-PP13TFSI showed specific capacity of 196 mAh (g-RuO2) 1 and specific energy of 625 Wh (kg-RuO2) 1 in 2.0 M acetic acid-lithium acetate buffered solution at 25˚C.

Conducting Nanosheets and Nanoparticles for Supercapacitors and Fuel Cell Electrocatalysts

“…Changing Li foil to pre-lithiated graphite (Li x C 6 ) particles and addition of N-methyl-N-propylpiperidinium bis(trifluoromethansulfonyl)imide (PP13TFSI) ionic liquid into the polymer electrolyte increased the conductivity of the protected anode, and the resistance of the protected Li x C 6 anode was 1/6 of that of protected Li anode, allowing room temperature operation of the cell. 46 Combining this improved protected Li x C 6 anode with a RuO 2.0 nanosheet cathode, maximum capacitance of 196 mAh (g-RuO 2 ) ¹1 and specific energy of 625 Wh (kg-RuO 2 ) ¹1 was achieved at room temperature ( Fig. 9).…”

“…For the Li + conducting solid electrolyte, a 150 µm NASICON-type glass ceramic Li 1+x+y (Ti,Ge) 2¹x Al x Si y P 3¹y O 12 (x ³ 0.25, y ³ 0.3) (LTAP) is used. 41,[45][46][47][48] The polymer electrolyte (PEO-LiTFSI: polyethylene oxide polymer doped with Li(CF 3 SO 2 ) 2 N) or alginate gel acts as a buffer layer to avoid contact of Li with LTAP. Figure 8 shows charge/discharge curves of one of our earlier proof-of-concept cells (Li « PEO-LiTFSI « LTAP « AcOLi-AcOH« RuO 2.0 nanosheets).…”

“…9). 46 Interested readers are suggested to refer to a recent review 45 regarding details of the 4-V aqueous hybrid supercapacitor technology.…”

“…Left axis: Cell voltage in two-electrode configuration (black). Right axis: potential of RuO 2.0 nanosheet positive electrode (red) and Li x C 6 negative electrode (blue) 46.…”

Improved Water-stable Protected Anodes with Low Resistance for Aqueous Energy Storage Devices

“…5,6 The adoption of aqueous electrolyte allows the use of pseudocapacitive positive electrodes (e.g. RuO 2 and MnO 2 ) with high specific capacitance, [5][6][7][8][9] with the advantage of increasing the maximum operating cell voltage to 4 V instead of 1 V for pure aqueous electrolytes. However, owing to the multi-component structure, the total resistance of the protected anode is high and is not suitable for high power applications.…”