The recent revival of Li metal anodes (LMA) leads to a renewed interest in LMA as the ultimate choice for rechargeable lithium batteries towards high energy density. However, multiple challenges stand in the way of using LMA, of which high reactivity, dendrite growth, the difficulty of fabricating Li thin foils, and the flammability of organic liquid electrolytes are typical. Here, a writable Li metal ink (LMI) prepared by introducing biomass-derived carbon particles into molten Li is presented. Due to the significantly decreased surface tension, LMI is able to directly write on copper foils or other substrates that ultrathin Li foils with a remarkably small thickness (<10 µm) can be achieved. The versatility of LMI is further demonstrated in addressing the interface issue between LMA and garnet-type solid-state electrolytes, where directly writing LMI on the garnet offers a perfect contact and enables an extremely low interfacial resistance of 6 Ω cm², in sharp contrast to 939 Ω cm² between the pure Li and the garnet. Due to the successful partnership with non-flammable solid-state electrolytes, ink-based technology may have a chance to bring us very close to the use of solid-state lithium metal batteries (SSLMBs) with high safety and high energy density.

锂金属阳极（LMA）的近期复兴引起了人们对LMA的重新关注，因为LMA是可充电锂电池向高能量密度的最终选择。然而，使用LMA的方式面临多种挑战，其中典型的是高反应性，枝晶生长，制造Li薄箔的难度以及有机液体电解质的可燃性。这里，提出了通过将源自生物质的碳颗粒引入熔融的Li中而制备的可写Li金属油墨（LMI）。由于表面张力显着降低，LMI可以直接在铜箔或其他基材上书写，从而可以实现厚度极小（<10 µm）的超薄锂箔。解决LMA与石榴石型固态电解质之间的界面问题进一步证明了LMI的多功能性，²与纯Li和石榴石之间的939Ωcm ²形成鲜明对比。由于与不可燃固态电解质的成功合作，基于墨水的技术可能使我们非常接近使用具有高安全性和高能量密度的固态锂金属电池（SSLMB）。