Polymer hetero-electrolyte enabled solid-state 2.4-V Zn/Li hybrid batteries

Abstract

The high redox potential of Zn^0/2+ leads to low voltage of Zn batteries and therefore low energy density, plaguing deployment of Zn batteries in many energy-demanding applications. Though employing high-voltage cathode like spinel LiNi_0.5Mn_1.5O₄ can increase the voltages of Zn batteries, Zn²⁺ ions will be immobilized in LiNi_0.5Mn_1.5O₄ once intercalated, resulting in irreversibility. Here, we design a polymer hetero-electrolyte consisting of an anode layer with Zn²⁺ ions as charge carriers and a cathode layer that blocks the Zn²⁺ ion shuttle, which allows separated Zn and Li reversibility. As such, the Zn‖LNMO cell exhibits up to 2.4 V discharge voltage and 450 stable cycles with high reversible capacity, which are also attained in a scale-up pouch cell. The pouch cell shows a low self-discharge after resting for 28 days. The designed electrolyte paves the way to develop high-voltage Zn batteries based on reversible lithiated cathodes.

Zn batteries suffer from low voltage due to the high redox potential of the Zn anode and the low potential of traditional cathodes. Here, the authors develop a polymer hetero-electrolyte, which allows separated Zn and Li reversibility and achieves a 2.4 V-Zn battery based on the LiNi_0.5Mn_1.5O₄ cathode.