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[Display omitted] • Composites of polyimide derived carbon nanofibers and MnO 2 nanosheets are reported. • The structure effectively suppresses Jahn-Teller effect and promotes fast Zn2+ ion diffusion. • The combination of delicate fiber and salty ice electrolyte enables excellent electrochemical performance. • A potential low temperature electrolyte is demonstrated. • The cell can work at a low temperature of −20 °C and 500 cycles is achieved under 0 °C. Mn-based aqueous zinc-ion batteries are potential candidates for energy storage owing to the low cost, high efficiency, and safety. Nevertheless, the Jahn–Teller effect induces Mn2+ dissolution and irreversible phase changes, seriously deteriorating the cycling life. Herein, the facile construction and low temperature performance of the core–shell composites of polyimide derived nitrogen-doped carbon nanofibers and δ-MnO 2 (δ-MnO 2 -CNFs) are reported, where ultrafine MnO 2 arrays are tightly anchored on carbon nanofibers. The hybrid effect of nitrogen doping, porous structure, and abundant active sites effectively inhibits the structural damage of MnO 2. The as-prepared δ-MnO 2 -CNFs cathode achieves a high specific capacity of 232.9 mAh g−1 and energy density of 450.7 Wh kg−1 at a current density of 100 mA g−1, and could be stably cycled for 500 cycles at a high current rate of 1 A g−1. The density functional theory calculation results show that the synergistic effect in δ-MnO 2 -CNFs is more conducive to the transfer of zinc ions. Furthermore, a salty ice electrolyte Zn(ClO 4) 2 has been used for the Zn//δ-MnO 2 -CNFs cell, which can work at a low temperature of −20 °C, and a stable low temperature (0 °C) cycle of 500 cycles is achieved at 1 A g−1. [ABSTRACT FROM AUTHOR]