No abstract

Lithium (Li) metal batteries have attracted massive research interest as candidates for a high energy density system. However, the instability and dendrite issue of Li metal have substantially hindered their practical applications. Therefore, we proposed a well-designed three-dimensional honeycomb-like hierarchical nitrogen (N)-doped framework (HHNF) as a matrix for Li deposition. Many Li ions can be distributed and reduced uniformly through the strong adsorption of N-containing functional groups in the HHNF. Metallic Li deposition on the HHNF follows an “inside–outside” mechanism, and the deposited Li spreads evenly on a flat surface when the internal porous space is filled completely. In this work, homogeneous Li deposition and the avoidance of Li dendrite formation are demonstrated by in situ optical microscopy and in situ Raman spectroscopy. The HHNF performs a high and stable Coulombic efficiency (98.5%) within 400 cycles and an ultralong lifespan of 1000 h at 0.5 mA cm–2 with a low potential polarization (23.8 mV) according to the symmetric cell test. In addition, full cells based on HHNF@Li anodes and LiFePO4/sulfur cathodes exhibit outstanding reversible capacities and rate performance (144.1 mAh g–1 for LiFePO4 after 150 cycles and 676.2 mAh g–1 for sulfur after 100 cycles at 0.5 C).

Due to the unavoidable generation of lithium (Li) dendrites, stable and sustainable Li metal batteries are still facing great difficulties in practical applications. Herein, a free-standing porous copper framework decorated with Sn nanoparticles (PCF@Sn) is proposed for the uniformly induced and dispersed Li deposition. Benefiting from the formation of a lithiophilic Li-Sn alloy, PCF@Sn exhibits a homogeneous and ordered distribution of the deposited Li metal, which is manifested by in situ optical or microscopic images. In the test of Coulombic efficiency, a controlled incomplete delithiation behavior can further promote the prevention of Li dendrites and structure deterioration, realizing a longer and more stable cycling performance. In addition, a higher utilization of the deposited Li metal can also be achieved in the Li plating/stripping process. As a result, a symmetric cell based on PCF@Sn@Li electrodes delivers an extremely stable cycling performance of 1200 h at 1 mA cm −2 and rate capability. For full cell tests, PCF@Sn@Li anodes show excellent reversible capacities, superior capacity retentions, and excellent rate performance when coupled with LiFePO 4 or sulfur cathodes.

The commercial application of lithium (Li) metal batteries is hindered by Li dendrite related severe safety issues. Herein, a functional self-supporting skeleton decorated with dual lithiophilic Sn-containing and N-doped carbon...