Lithium Dredging and Capturing Dual-Gradient Framework Enabling Step-Packed Deposition for Dendrite-Free Lithium Metal Anodes

Due to the sterile lithium affinity and poor Li+ regulation ability, lithium metal tends to deposit on the top of substrate materials, which lowers the space utilization and deteriorates the dendrites growth, further increasing the risk of short circuits. It is necessary to guide lithium deposition and adjust Li+ flux at the base of substrate toward alleviating those issues of lithium metal anodes (LMAs). Herein, a dredging and capturing dual-gradient framework is conveniently fabricated toward inducing the Li+ migration and deposition. The dual-gradient framework combined with upper Ni3S2 nanowires with lower Li+ migration barrier and bottom Ni2P nanowires with stronger Li affinity, such reasonable distribution of components conquers the ionic concentration gradient to acquire a "step-packed" lithium deposition mode. Moreover, the in situ formation of Li2S/Li3P-enriched SEI further promotes Li+ transport to the interior framework. Consequently, a high average Coulombic efficiency of 98% over 230 cycles and a lifespan of 180 h (10 mA cm-2, 5 mAh cm-2) are achieved. The LiFePO4 full cells also exhibit a considerable capacity retention. This work provides a feasible strategy of step-packing lithium deposition for significant framework design insight to boost practical lithium metal batteries (LMBs) development. The lithium dredging and capturing dual-gradient framework combined with upper Ni3S2 nanowires with lower Li+ migration barrier and bottom Ni2P nanowires with strong Li affinity, which induces Li+ migration and deposition, acquires a "step-packed" lithium deposition mode. The LiFePO4 full cells (10 mg cm-2) exhibit a considerable capacity retention of 91.4% after 500 cycles at 1C.image