Dual-functional mediators of high-entropy Prussian blue analogues for lithiophilicity and sulfiphilicity in Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries are considered promising next-generation energy storage systems due to their high energy density (2600 W h kg⁻¹) and cost-effectiveness. However, the shuttle effect of lithium polysulfides in sulfur cathodes and uncontrollable Li dendrite growth in Li metal anodes significantly impede the practical application of Li–S batteries. In this study, we address these challenges by employing a high-entropy Prussian blue analogue Mn_0.4Co_0.4Ni_0.4Cu_0.4Zn_0.4[Fe(CN)₆]₂ (HE-PBA) composite containing multiple metal ions as a dual-functional mediator for Li–S batteries. Specifically, the HE-PBA composite provides abundant metal active sites that efficiently chemisorb lithium polysulfides (LiPSs) to facilitate fast redox conversion kinetics of LiPSs. In Li metal anodes, the exceptional lithiophilicity of the HE-PBA ensures a homogeneous Li ion flux, resulting in uniform Li deposition while mitigating the growth of Li dendrites. As a result, our work demonstrates outstanding long-term cycling performance with a decay rate of only 0.05% per cycle over 1000 cycles at 2.0 C. The HE-PBA@Cu/Li anode maintains a stable overpotential even after 600 h at 0.5 mA cm⁻² under the total areal capacity of 1.0 mA h cm⁻². This study showcases the application potential of the HE-PBA in Li–S batteries and encourages further exploration of prospective high-entropy materials used to engineer next-generation batteries.