Design, Synthesis, and Characterization of Polyphosphazene Bearing Stable Nitroxide Radicals as Cathode-Active Materials in Li-Ion Batteries

Abstract

A new synthetic strategy is developed for the synthesis of polyphosphazene bearing stable nitroxide radicals as a pendant group. The resulting material is investigated as a cathode‐active material for rechargeable lithium–ion batteries that performs 80 mAh g−1 capacities at a C/2 current density over 50 cycles. Thus, the inorganic–organic hybrid system can be proposed as an alternative cathode‐active material with improved performance.

A novel polyphosphazene with nitroxide radical side groups as cathode‐active material in Li‐ion batteries

“…Although the initial decomposition temperature of PNPP is around 92°C, it is not detrimental for the LIB applications since most of the common carbonate electrolytes start being decomposed much earlier. The EPR spectrum of the PNPP as seen in Figure B showed three hyperfine split lines with g factor (with respect to the value of the free electron) of 2.0074 that is consistent with our previously published studies …”

“…31 P NMR spectrum of PNPP exhibited a single peak at −19.66 ppm as expected and shown in Figure A. 1 H NMR spectrum of the PNPP polymer reveals that it has two different peak groups consisting of the aromatic protons (6.5‐7.8 ppm) and the tert‐butyl group protons (1.29‐1.49 ppm) . Particularly, IR spectra of polymers indicated the conversion of the all N─OH units to the N─O .…”

“…In order to prepare the targeted cathode material ( PNPP ), our previously developed synthetic methodology, which is a two‐step macromolecular nucleophilic substitution process, is modified and improved, and its synthetic route is shown in Figure . Firstly, poly (dichlorophosphazene) ( PDCP ) is prepared by according to the literature procedure .…”

“…Recently, we have demonstrated a new synthetic approach to obtain stable nitroxide radicals appended polyphosphazene . The stable nitroxyl radicals onto polyphosphazene compound resulted a charge capacity of 133 mAh/g in the first cycle as theoretical capacity afforded important insights into the development of much more effective cathode‐active materials.…”

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

“…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 phenoxyl radical was used in a polynorbornene in form of tetramethylphenoxyl units, but a built hybrid lithium‐ion cell showed a capacity of only 60 mAh g −1 , losing 20 % capacity over the first 100 cycles …”