Atomic Sn–enabled high-utilization, large-capacity, and long-life Na anode

Constructing robust nucleation sites with an ultrafine size in a confined environment is essential toward simultaneously achieving superior utilization, high capacity, and long-term durability in Na metal-based energy storage, yet remains largely unexplored. Here, we report a previously unexplored design of spatially confined atomic Sn in hollow carbon spheres for homogeneous nucleation and dendrite-free growth. The designed architecture maximizes Sn utilization, prevents agglomeration, mitigates volume variation, and allows complete alloying-dealloying with high-affinity Sn as persistent nucleation sites, contrary to conventional spatially exposed large-size ones without dealloying. Thus, conformal deposition is achieved, rendering an exceptional capacity of 16 mAh cm−2 in half-cells and long cycling over 7000 hours in symmetric cells. Moreover, the well-known paradox is surmounted, delivering record-high Na utilization (e.g., 85%) and large capacity (e.g., 8 mAh cm−2) while maintaining extraordinary durability over 5000 hours, representing an important breakthrough for stabilizing Na anode

Metal nitride heterostructures capsulated in carbon nanospheres to accommodate lithium metal for constructing a stable composite anode

Although various hosts have been proposed to accommodate the Lithium (Li) metal to solve the uneven Li deposition and infinite volume change, the pulverization of the host or lithiophilic modification layer easily leads to structural damage and the poor cycling stability of the composite anode. Herein, we design a host of metal nitrides (Mo2N and WN heterostructures) nanoparticles capsulated in the hollow carbon nanospheres, which can accommodate Li metal to form a stable composite anode. The lithiophilic Mo2N guides uniform infusion and reduces the nucleation barriers of Li metal during electrochemical process. Note that the rigid WN matrix is uniformly composited with Mo2N, which can suppress the pulverization of Mo2N during the repeat Li plating/stripping, ensuring the stability of regulated deposition during long cycling. High mechanical strength, uniform surface potential distribution and good electrolyte wettability of the Li metal-based composite anode guarantee the rapid Li plating/stripping kinetics. Thus, the obtained composite anode can stably cycle 1400 h at 1 mA cm-2 and 1 mA h cm-2 in the symmetric battery. The assembled full cells with LiNi0.8Mn0.1Co0.1O2 (NCM811) also deliver high capacity retention under the high loading (8.6 mg cm-2) or lean electrolyte (2 μL mg-1) condition. This work suggests a promising host structure design to construct a highly stable lithium metal anode for practical applications