Polytriphenylamine Derivative and Carbon Nanotubes as Cathode Materials for High-Performance Polymer-Based Batteries

Abstract

Composites of polytriphenylamine (PTPA), its novel derivative poly­(4-carbamoyl-N,N-diphenylaniline-2,2,5,5-tetramethyl-pyrrolin-1-oxyl) (PTPA-PO), and multiwalled carbon nanotubes (CNTs) were synthesized by in situ polymerization. The characterization results showed that the CNTs were homogeneously distributed in the polymer matrix and formed a cross-linked conductive network. The electrical properties of PTPA/CNT composites were better than those of traditional acetylene black as conductive agents. Electrochemical tests showed that the initial specific discharge capacity of the PTPA/CNT composites was 107.6 mAh g–1 (theoretical capacity of PTPA is 109 mAh g–1). Furthermore, further research to increase the specific capacity demonstrated that the as-synthesized polytriphenylamine derivative, PTPA-PO, with a CNT cathode presented two well-defined plateaus and an enhanced discharge capacity of 139.3 mAh g–1. Additionally, the PTPA-PO/CNT electrode showed superior cycling performance and remained above 90% of the initial capacity after 100 cycles. The enhanced electrochemical performance of PTPA-PO was due to its combination of the conducting polymer PTPA and free radical active site pendant PO, which increased its electrochemical reaction rate, and this composite is a promising material for high-performance polymer-based organic batteries.

Sustainable Energy Storage: Recent Trends and Developments toward Fully Organic Batteries

“…The overall capacity was 120 mAh g −1 , losing 10 % over 100 cycles. Subsequently, the same group attempted to enhance the electrochemical performance by the introduction of MWCNTs, but no significant improvement was achieved . A polymer of the 1,1,3,3‐tetramethylisoindolin‐2‐yloxyl radical showed a comparable performance in a lithium‐ion cell, whereas a polyphosphazene bearing an N‐tert ‐butyl‐ N ‐oxylamino phenyl radical unit resulted in a higher initial capacity of 145 mAh g −1 but a capacity drop of 35 % during the first 50 cycles .…”

“…A cell based on a polytriphenylamine and a graphite electrode and a potassium hexafluorophosphate‐based electrolyte was demonstrated, displaying a stable voltage but a low capacity of 60 mAh g −1 and a coulombic efficiency of only 80 % . Dong and co‐workers prepared a polytriphenylamine on MWCNTs via in situ polymerization of triphenylamine in a dispersion of MWCNTs . Subsequently, the authors built a hybrid lithium‐ion cell without additional conductive additives, which revealed a stable voltage of 3.7 V and a capacity of 100 mAh g −1 , retaining 85 % after 100 cycles.…”

“…Subsequently,t he same group attempted to enhancet he electrochemical performance by the introduction of MWCNTs,b ut no significant improvementw as achieved. [121] Ap olymer of the 1,1,3,3-tetramethylisoindolin-2yloxyl radical showedacomparablep erformance in al ithiumion cell, [122] whereas ap olyphosphazene bearing an N-tertbutyl-N-oxylamino phenylr adicalu nit resulted in ah igher initial capacity of 145 mAh g À1 but ac apacity drop of 35 %d uring the first 50 cycles. [123] Aphenoxyl radicalwas used in apolynorbornenei nf orm of tetramethylphenoxyl units, but ab uilt hybrid lithium-ion cell showed ac apacity of only 60 mAh g À1 , losing 20 %c apacity over the first 100 cycles.…”

“…[133] Dong and co-workers prepared ap olytriphenylamine on MWCNTsvia in situ polymerizationo ft riphenylamine in adispersion of MWCNTs. [121] Subsequently,t he authors built ah ybrid lithium-ion cell without additional conductive additives, which revealed as table voltage of 3.7 Va nd ac apacity of 100 mAh g À1 ,r etaining 85 %a fter 100 cycles.…”

Nitroxide radical cathode material with multiple electron reactions

“…Another solution is to attach radicals to a conductive skeleton, for example, polytriphenylamine (PTPA) [26]. Dong's and Zhang's groups attached 2,2,5,5-tetramethyl-3-pyrrolin-1-oxyl (PO) and 2,2,6,6-tetramethylpiperidiny-N-oxyl (TEMPO) to PTPA, respectively [27][28][29], which presented both p-type and n-type reactions in the favor of conductive PTPA. Unfortunately, the introduced PTPA skeleton decreased the theoretical capacity (~180 mAh g À1 ), which is much lower than poly (2,2,6,6-tetramethylpiperidinyloxy methacrylate (PTMA) (223 mAh g À1 ).…”