Low-cost fumed silicon dioxide uniform Li⁺ flux for lean-electrolyte and anode-free Li/S battery

Dendritic lithium (Li) growth hinders the applications of Li metal anode. Here, a fumed SiO₂ is proposed as an electrolyte additive to realize uniform Li⁺ deposition. Due to the abundant hydroxyl group on the surface, the SiO₂ particles as a pump provide an additional way for Li⁺ transport, resulting in a homogeneous Li⁺ flux. Moreover, SiO₂ can also smooth the deposited Li and boost the formation of a LiF-rich SEI. As a result, the anode-free Li₂S/Cu cell demonstrates a significantly improved rechargeability (1055 mAh g⁻¹, 1^st cycle; 523 mAh g⁻¹, 200^th cycle). Moreover, even with limited electrolyte (electrolyte/sulfur ratio, 7 µL mg⁻¹) and Li (negative to positive capacity ratio, 3), the Li/S pouch cells can still maintain a high capacity of 689 mAh g⁻¹ after 200 cycles. This work shows a simple and efficient way for constructing high-energy-density Li metal batteries.