Gradient lithiation to load controllable, high utilization lithium in graphitic carbon host for high-energy batteries

The multiphase interaction between Li metal and carbon materials provides great opportunities to design advanced composite anodes for Li metal batteries. Herein, we report the conversion of single-sheet graphitic carbon papers (CPs) to function-gradient Li/C composite anodes with controllable formations of LiC 6 and Li metal through controlling the thermal infiltration time. The uniform and dense lithiophilic LiC 6 is formed first and gradually covers the entire CP host, which promotes the subsequent homogeneous infiltration of metallic Li into the CP. The resulting composite anode has a unique gradient structure, with one example consisting of a lithiated LiC 6 coating of 5.8 mAh cm −2 and a thin Li bottom layer of 2.7 mAh cm −2 . Such a gradient composite structure allows for the selective utilization of Li metal and LiC 6 as the active component under different electrochemical conditions. This composite anode, with a much leaner Li loading than many reported Li/C composite anodes, has a stable porous framework and abundant lithiophilic sites, which enables uniform local electric field and stable Li metal deposition during cycling. Paired with high-capacity cathodes, the composite anode, with only a fraction of Li metal loading compared to Li foil, can provide better long-term cycling stability, and higher rate capability. A unique gradient lithiated electrode is achieved by directly contacting the carbon paper with molten Li. Paired with high-capacity cathodes, the gradient anode, with only a fraction of Li metal loading compared to Li foil, can provide better long-term cycling stability. • The multiphase interaction between Li metal and carbon paper promotes the formation of a gradient lithiation electrode. • Such gradient electrode retains a stable framework and abundant lithiophilic sites to promote stable Li plating/stripping. • The gradient electrode allows for the selective utilization of Li metal under different electrochemical conditions. • The gradient electrode exhibits better long-term cycling stability and higher rate capability compared to the Li foil.