A TEMPO-substituted polyacrylamide as a new cathode material: an organic rechargeable device composed of polymer electrodes and aqueous electrolyte

Abstract

Poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl acrylamide) was designed and synthesized as an electrode-active polymer for an organic rechargeable device containing an aqueous electrolyte. The device demonstrated a 1.2 V output voltage, exceeded 2000 charging-discharging cycles, and had a high charging rate performance within 1 min.Polyacrylamide is a well-known hydrophilic soft matter widely used in cell culture, drug delivery, and soil amendment. 1-4 Its applications have been vigorously studied in the biological, medical and agricultural fields. On the other hand, the study of the electronic energy related application has been minor and limited to polymer electrolyte fuel cells. 5 We now report a new application of polyacrylamide as an electrode-active material in organic rechargeable devices.Organic-based electrode-active materials have been paid considerable attention because of their potential to overcome the inherent disadvantages of metal-based electrodes, such as limited raw-material resource and tedious waste process. We have focused on the reversible redox reaction of radical species, such as nitroxide, phenoxyl and galvinoxyl radicals, synthesizing a series of aliphatic polymers bearing pendant radical groups (we call them "radical polymer"), and utilizing them as an electrode-active or charge-storage material in a rechargeable device. 6-13 A typical example of a radical polymer is poly(2,2,6,6tetramethylpiperidinyloy-4-yl norbornene). 10 This polymer contains 2,2,6,6-tetramethylpiperidin-1-oxyl-4-yl (TEMPO) groups which are rapidly, reversibly, and stoichiometrically oxidized to the corresponding oxoammonium cation. The poly(TEMPOsubstituted norbornene) was used as the positive electrode (the cathode) ‡ and coupled with a lithium metal negative electrode (an anode) ‡ in a semi-organic rechargeable device containing a LiPF 6 ethylene carbonate/diethyl carbonate (1/1) solution. The device demonstrated a high charging-discharging performance, such as a 3.6 V output voltage, rapid charging within 1 min, and exceeded 1000 charging-discharging cycles. 12 In addition, a test cell composed of the poly(TEMPO-substituted norbornene) cathode, poly(galvinoxylstyrene) anode and (

Polymers with n-type nitroxide side groups: Synthesis and electrochemical characterization

“…Typically, nitroxides are often embedded in rings, like the six-membered ring of the TEMPO-radical [8][9][10][11][12] or the five-membered ring in the PROXYL-radical [14]. These radicals are often used in organic radical batteries [2,3,5,6,[8][9][10][11][12]15,16] and organic memory devices [17] because of their reversible redox-chemistry.…”

“…These radicals are often used in organic radical batteries [2,3,5,6,[8][9][10][11][12]15,16] and organic memory devices [17] because of their reversible redox-chemistry.…”

“…Common polymer-backbones functionalized with nitroxides are, e.g., methacrylate [6], acrylate [18], norbornene [12], vinylether [9], styrene [16] or acrylamide [8]. These materials, in particular polymers with TEMPO moieties, have been applied as redox-active material in organic radical batteries (ORBs).…”

“…Today there are hundreds of stable nitroxide-radicals known and one of the most commonly used nitroxide is the 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) radical [1][2][3][8][9][10][11][12]. Nitroxide-radicals are usually stable against water and air.…”

Hybrid Organic Electrodes: The Rational Design and Synthesis of High-Energy Redox-Active Pendant Functionalized Polypyrroles for Electrochemical Energy Storage

“…15 For example, polyacrylamide with TEMPO ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl or (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl), as the redox-active pendant (RAP) exhibited a practical capacity of 114 mAh/g for up to 2000 cycles with 80% capacity retention. [17][18][19][20][21] However, the electronically z E-mail: hda1@cornell.edu; coates@cornell.edu insulating nature of the polymer backbone required the addition of more than 50 weight% conducting additives (typically carbon) in electrode fabrication. [15][16][17][18][19][20][21] As a result, the practical capacities of these composites are significantly lower than expected (especially when normalized to the total weight of the composite, not just the active material).…”