Constructing Lithium-Free Anode/Separator Interface via 3D Carbon Fabric Scaffold for Ultrasafe Lithium Metal Batteries.

Metallic lithium represents a promising anode candidate to be utilized in future high-energy lithium batteries. However, the undesirable dendrite growth and fragile solid-electrolyte interphase (SEI) pose critical challenge for pursuing further practical application. In contrast to traditional approaches of using inert/lithiophilicity coating, here, we demonstrate a reverse strategy of introducing a highly conductive and lithophobic carbon fabric (CF) scaffold on lithium foil to guide a favorable nucleation site of lithium far away from the anode/separator interface. The CF scaffold with high conductivity can couple with inner electric field for achieving a uniform distribution of the lithium-ion flux, while the lithophobic feature offers the condition to guide the preferred deposition of lithium onto the underlying lithium foil, which greatly reduces the risk of dendrite-induced short circuits. Moreover, the SEI immersed in the CF scaffold is well supported by CF fibers and therefore exhibits extremely high stability during charge-discharge cycles. As a result, the lithium/CF anodes show >2,000-h stable cycling at 0.5 mA cm-2. Lithium metal batteries equipped with our lithium/CF anode deliver a high capacity retention of ~99.99% per cycle, i.e., retain ~97.3% capacity after 200 cycles. The unique interface-regulation strategy is versatile for various conductive scaffolds (e.g., ultrathin and ultralight conductive fabrics), exhibiting high superiority for highly safe lithium metal batteries.

Simultaneous Interphase Optimizations on the Large-Area Anode and Cathode of High-Energy-Density Lithium-Ion Pouch Cells by a Multiple Additives Strategy.

Prior to the maturation of next-generation energy storage devices, the actual lithium-ion batteries for commercial purposes are still expected to fulfill some critical requirements, among which the high energy density, wide operating temperature range, and related long-term cycling stability are the most challenging issues. Herein a multiple additives strategy is employed to simultaneously optimize the solid electrolyte interphase on the large-area anode and cathode in a 2 Ah artificial graphite (AGr)/LiNi0.5Co0.2Mn0.3O2 (NCM523) pouch cell with high gravimetric (>260 Wh kg-1) and volumetric (>630 Wh L-1) energy density. By introducing a rational mixture of electrolyte additives, a highly sulfurized surface layer and a uniform and thin passivation layer are separately formed on the anode and cathode of the AGr/NCM523 pouch cell, exhibiting high storage stability at 60 °C, much improved discharge capacity at -10 and -20 °C, high anodic stability at high voltage of 4.4 V, and stable cyclic performance with a capacity retention of 85.5% after 500 cycles, significantly outperforming the value of 75.7% after only 200 cycles of the cell without additional additives. These results demonstrate the critical effect of simultaneous optimizations of anode and cathode interphase layers to construct stable high-energy-density lithium-ion pouch cells.