Charge–discharge behavior of a Na2FeP2O7 positive electrode in an ionic liquid electrolyte between 253 and 363 K

Abstract

The electrochemical properties of a Na 2 FeP 2 O 7 positive electrode were investigated in the ionic liquid sodium bis(fluorosulfonyl)amide (NaFSA)-N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)amide (C 3 C 1 pyrrFSA). A stable charge-discharge behavior was obtained over the temperature range 253-363 K. The cell offered nearly a one-electron theoretical capacity of about 90 mAh g −1 at 298-363 K. The rate capability showed considerable enhancement with increasing temperature, delivering 50 mAh g −1 at a very high rate of 4000 mA g −1 (ca. 41 C) at 363 K. Furthermore, the Na 2 FeP 2 O 7 positive electrode demonstrated excellent cyclability, exceeding 300 cycles, in terms of both capacity retention and coulombic efficiency at 298-363 K, as only negligible capacity fade (<1%) was observed. This good performance over a wide temperature range will meet the requirements of the versatile applications expected for Na secondary batteries.promising platform for the broad spectrum of applications expected for Na secondary batteries. 4 5 6 7 8

Full Utilization of Superior Charge-Discharge Characteristics of Na1.56Fe1.22P2O7Positive Electrode by Using Ionic Liquid Electrolyte

“…24,28 The positive electrode was prepared by mixing Na 2-x Fe 1+x/2 P 2 O 7 , acetylene black and polytetrafluoroethylene in a weight ratio of 75:20:5. The mass loading and thickness of the active material were around 2.0 mg cm -2 and 50 μm, respectively.…”

“…20,21 However, the adoption of IL electrolytes for Na batteries has received less attention so far. 22,23 In our previous studies, the charge-discharge behavior of Na 2 FeP 2 O 7 electrodes in Na[FSA]-[C 3 C 1 pyrr][FSA] (where FSA = bis(fluorosulfonyl)amide and C 3 C 1 pyrr = N-methyl-Npropylpyrrolidinium) IL electrolytes was investigated over a wide temperature range of 253-363 K. 24 The results revealed a considerable enhancement in rate capability with increasing temperature along with an outstanding cyclability, implying that there are significant opportunities to improve the performance of Na secondary batteries by utilizing an IL electrolyte. Another advantage of using IL electrolytes is that the operation of the batteries at high temperatures is favorable to fully draw the potential capacity of the electrode material.…”

Structural and Electrochemical Properties of Hard Carbon Negative Electrodes for Sodium Secondary Batteries Using the Na[FSA]&ndash;[C₃C₁pyrr][FSA] Ionic Liquid Electrolyte

“…[1][2][3][4][5][6][7][8][9][10][11] Sodium is abundant in the crust and seawater, showing a relatively low standard redox potential (¹2.71 V vs. SHE). Thus, batteries with low cost and high energy density can be constructed.…”

Charge-discharge Performance of an Ionic Liquid-based Sodium Secondary Battery in a Wide Temperature Range

“…The semicircle at the middle frequency corresponds to the electrochemical reaction process which includes both positive and negative electrode reactions. 21,22 The electrochemical reaction resistance (R ER ) largely increases with lowering the operating temperature, indicating a significant sensitivity to temperature. ) and Q (E a = 23.7 kJ mol ¹1 ), which supports that R ³ is due to the electrolyte resistance.…”

“…More importantly, the value of R ER is much larger than that of R ³ , which indicates that the total cell resistance is mainly governed by R ER . In our previous study, 21 the impedance of Na/Na symmetric cell was measured at different temperatures, which revealed that the major component of R ER originates from the Na metal electrode, especially at lower temperatures. Thus, it is concluded that the drastic decrease of capacity at lower temperatures in the present study is mainly caused by the higher R ER of Na counter electrode.…”