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<inf>0.5</inf>Mn<inf>1.5</inf>O<inf>4</inf> can increase the voltages of Zn batteries, Zn²⁺ ions will be immobilized in LiNi<inf>0.5</inf>Mn<inf>1.5</inf>O<inf>4</inf> 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.