A diluent protective organic additive electrolyte of hydrophilic hyperbranched polyester for long-life reversible aqueous zinc manganese oxide batteries

A hydrophilic hyperbranched polyester (poly (tetramethylol acetylenediurea (TA)-CO-succinyl chloride) (PTS)) was proposed to be used as an organic additive in aqueous ZnSO₄ electrolyte to achieve a highly reversible zinc/manganese oxide battery. It is found that the zinc symmetric battery based on the 2.0 wt.% PTS/ZnSO₄ electrolyte showed a long cycle stability of more than 2400 h at 1.0 mA·cm⁻², which is much longer than that including the blank ZnSO₄ electrolyte (140 h). Furthermore, the capacity retention of the Zn||MnO₂ full cells employing the 2.0 wt.% PTS/ZnSO₄ electrolyte remained 85% after 100 cycles at 0.2 A·g⁻¹, which is much higher than 20% capacity retention of the cell containing the blank ZnSO₄ electrolyte, and also greater than 59.6% capacity retention of the cell including the 10.0 wt.% TA/ZnSO₄ electrolyte. By using 2.0 wt.% PTS/ZnSO4 electrolytes, the capacity retention of the Zn||MnO2 full cells even reached 65% after 2000 cycles at a higher current density of 1.0 A·g⁻¹. It is further demonstrated that the PTS was firmly adsorbed on the zinc anode surface to form a protective layer.