Lithiophilic Magnetic Host Facilitates Target‐Deposited Lithium for Practical Lithium‐Metal Batteries

Abstract Lithium‐metal shows promising prospects in constructing various high‐energy‐density lithium‐metal batteries (LMBs) while long‐lasting tricky issues including the uncontrolled dendritic lithium growth and infinite lithium volume expansion seriously impede the application of LMBs. In this work, it is originally found that a unique lithiophilic magnetic host matrix (Co 3 O 4 ‐CCNFs) can simultaneously eliminate the uncontrolled dendritic lithium growth and huge lithium volume expansion that commonly occur in typical LMBs. The magnetic Co 3 O 4 nanocrystals which inherently embed on the host matrix act as nucleation sites and can also induce micromagnetic field and facilitate a targeted and ordered lithium deposition behavior thus, eliminating the formation of dendritic Li. Meanwhile, the conductive host can effectively homogenize the current distribution and Li‐ion flux, thus, further relieving the volume expansion during cycling. Benefiting from this, the featured electrodes demonstrate ultra‐high coulombic efficiency of 99.1% under 1 mA cm −2 and 1 mAh cm −2 . Symmetric cell under limited Li (10 mAh cm −2 ) inspiringly delivers ultralong cycle life of 1600 h (under 2 mA cm −2 , 1 mAh cm −2 ). Moreover, LiFePO 4 ||Co 3 O 4 ‐CCNFs@Li full‐cell under practical condition of limited negative/positive capacity ratio (2.3:1) can deliver remarkably improved cycling stability (with 86.6% capacity retention over 440 cycles).