A new hexa-armed star polymer bearing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-pending polymer chains emanating from a phosphazene core (P2) was prepared and used as the cathode material in Li-ion battery assembly. The properties of the assembled battery (BP2) were compared with those of BL2 assembled using its linear counterpart (L2). Their spin concentrations investigated via solution electron spin resonance (ESR) measurements were found to be almost the same. The charge/discharge capacities and energy densities of BP2 were considerably higher than those of BL2. However, they exhibited comparable charge/discharge efficiencies and their discharge capacities dropped to similar percentages of their initial values. (C) 2016 Elsevier B.V. All rights reserved.