N n dimethylformamide (dmf)

Poly(2,6-dimethyl-1,4-phenylene oxide) powder (PPO), 1-methylpyrrolidine (≥98%), and manganese (IV) oxide (5 μm, 99.99%) were supplied by Sigma-Aldrich (St. Louis, MO, USA). N-bromosuccinimide (NBS) for synthesis, benzoyl peroxide (BPO, with 25% H₂O), and chlorobenzene were purchased from Merck Millipore. 1-methyl-2-pyrrolidinone (NMP), ethanol, methanol, and toluene all with Grade AR were purchased from QRëC (New Zealand). N,N-dimethylformamide (DMF) (LOBA Chemie, Grade AR, Mumbai, India), trimethylamine (TCI, ca. 25% in methanol), 1-methylimidazole (TCI, ≥99%), chloroform (BDH Chemicals, UK), and KOH plates (Kemaus, Australia) were used as received without further purification. Nickel (Ni) foam as cathode current collector with a purity of 99.97%, 100 pores per inch (PPI), and 1 mm thick was purchased from Qijing Trading Co., Ltd. (Wenzhou, China). Carbon black (Vulcan^® XC-72, Cabot Corporation, Boston, MA, USA), BP-2000 (BLACK PEARLS^® 2000, Cabot Corporation), and zinc plate (0.1 mm thick 99.99%, Shandong Yr Electronic Co., Ltd., Shandong, China) were used as received. Poly (styrene-co-butadiene) (Sigma-Aldrich, butadiene 4 wt%) was used to prepare binder for the cathode. Poly(vinyl acetate) (PVAc) from TOA Paint Public Co., Ltd. (Samut Prakarn, Thailand) and No. 4 Whatman filter paper (Sigma-Aldrich) were used to prepare the benchmark separator.