An anion-immobilized composite electrolyte for dendrite-free lithium metal anodes

Abstract

<p id="d12971767e241">The Li metal electrode is regarded as a “Holy Grail” anode for next-generation batteries due to its extremely high theoretical capacity and lowest reduction potential. Unfortunately, uncontrolled dendrite growth leads to serious safety issues. This work realizes a dendrite-free Li metal anode by introducing an anion-immobilized composite solid electrolyte, where anions are tethered to polymer chains and ceramic particles. Immobilized anions contribute to uniform distribution of Li ions and dendrite-free Li deposition. The flexible electrolyte can be applied in all–solid-state Li metal batteries with excellent specific capacities. This work demonstrates a concept to adjust ion distribution based on solid-state electrolytes for safe dendrite-free Li anodes, paving the way to practical Li metal batteries. </p><p class="first" id="d12971767e244">Lithium metal is strongly regarded as a promising electrode material in next-generation rechargeable batteries due to its extremely high theoretical specific capacity and lowest reduction potential. However, the safety issue and short lifespan induced by uncontrolled dendrite growth have hindered the practical applications of lithium metal anodes. Hence, we propose a flexible anion-immobilized ceramic–polymer composite electrolyte to inhibit lithium dendrites and construct safe batteries. Anions in the composite electrolyte are tethered by a polymer matrix and ceramic fillers, inducing a uniform distribution of space charges and lithium ions that contributes to a dendrite-free lithium deposition. The dissociation of anions and lithium ions also helps to reduce the polymer crystallinity, rendering stable and fast transportation of lithium ions. Ceramic fillers in the electrolyte extend the electrochemically stable window to as wide as 5.5 V and provide a barrier to short circuiting for realizing safe batteries at elevated temperature. The anion-immobilized electrolyte can be applied in all–solid-state batteries and exhibits a small polarization of 15 mV. Cooperated with LiFePO ₄ and LiNi _0.5Co _0.2Mn _0.3O ₂ cathodes, the all–solid-state lithium metal batteries render excellent specific capacities of above 150 mAh⋅g ⁻¹ and well withstand mechanical bending. These results reveal a promising opportunity for safe and flexible next-generation lithium metal batteries. </p>