Preparation of Spherical δ−MnO2 Nanoflowers by One-Step Coprecipitation Method as Electrode Material for Supercapacitor - Dazhi Zhang; Jiamian Dai; Jiajia Zhang; Yixin Zhang; Honglai Liu; Yunhui Xu; Jianjun Wu; Peipei Li (ACS Omega, 2024)