Kosmotropic Anions-Intensified Proline Additive Enabling Highly Stable Zn Anodes

Abstract

Despite the conspicuous merits of Zn metal anodes, the commercialization of Zn anode-based electrochemical energy storage devices is still constrained by uncontrollable dendrite growth and serious parasitic reactions. Herein, an innovative strategy of employing kosmotropic anions-intensified proline additive to regulate the Zn²⁺ solvation structure and manipulate the Zn deposition interface, thus achieving highly stable Zn anodes, is proposed. The key to this strategy lies in ingeniously utilizing kosmotropic SO₄²⁻ anions to enhance the affinity of proline adsorption layer on the Zn anodes and weaken the solvation of Zn²⁺. Consequently, Zn anodes in the proline-containing ZnSO₄ (ZnSO₄-proline) electrolyte deliver a remarkable lifespan over 2600 h at 1.0 mA cm⁻² and 1.0 mAh cm⁻². Even under a harsh plating/stripping condition (10 mA cm⁻² and 10 mAh cm⁻²), Zn anodes in the ZnSO₄-proline electrolyte stably operate for 650 h. Meanwhile, the Coulombic efficiency of Zn plating/stripping in the designed electrolyte is as high as 99.9% over 1100 cycles. The ZnSO₄-proline electrolyte endows Zn-ion batteries and Zn-ion hybrid capacitors with notably optimized long-term cycling stability. This work is expected to be of immediate benefit to design low-cost Zn-based energy storage systems with ultra-long lifespan.