A 3D C@AlF multifunctional hollow spheres lithium host for lithium metal batteries.

Lithium (Li) metal has been deemed as an ideal anode for new generation rechargeable batteries owing to its unparalleled theoretical specific capacity, lowest electrochemical potential, and lightweight. However, volume expansion and the Li dendrites limit the performance of Li metal batteries (LMBs). In this work, we design a C@AlF hollow spheres as multifunctional lithium anode host material for Li metal battery. The hollow carbon spheric structure effectively accommodates Li to alleviate the volume expansion, and the lithiophilic AlF forms Li-Al alloy (LiAl) and LiF solid electrolyte interphase (SEI) with Li. The LiAl alloy guides the Li uniformly depositing inside the inner surface to suppress the Li dendrites formation. The LiF SEI is beneficial for Li flux to further facilitate the Li uniform deposition. Therefore, the designed Li metal anode demonstrates a lifespan over 2000 h for symmetric cells and voltage hysteresis less than 10 mA. When assembled with LiFePO cathode, the full cell provides a reversible capacity of 91.6 mAh g after 300 cycles at 1C. Our work here provides a feasible route to design a Li metal anode for high performance LMBs.