Stable Li metal anodes have become the driving factor for high-energy-density battery systems. However, uncontrolled growth of Li dendrite hinders the application of rechargeable Li metal batteries (LMBs). Here, a multifunctional electrolyte additive bisfluoroacetamide (BFA) was proposed to facilitate high-performance LMBs. The uniform and dense deposition of Li⁺ was achieved due to the reduced nucleation and plateau overpotential by the addition of BFA. Moreover, X-ray photoelectron spectroscopy (XPS) tests reveal a gradient solid electrolyte interface (SEI) structure on the Li metal surface. Cyclic voltammetry (CV) curves at different sweep speeds prove the formation of pseudocapacitance at the electrode–electrolyte interface, which accelerates the Li⁺ transport rate and protects the electrode structure. The low activation energy also indicates the ability of rapid Li⁺ transportation in electrolyte bulk. Therefore, the Li||Li symmetric cells with 1.0 wt.% BFA electrolyte exhibit good cycling performance at 0.5 mA·cm⁻² for over 2000 h, and Li||LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) full cells maintain a high capacity for 200 cycles at 1 C rate.

In this study, a boron-doped microporous carbon (BMC)/sulfur nanocomposite is synthesized and applied as a novel cathode material for advanced Li-S batteries. The cell with this cathode exhibits an ultrahigh cycling stability and rate capability. After activation, a capacity of 749.5 mAh/g was obtained on the 54^th cycle at a discharge current of 3.2 A/g. After 500 cycles, capacity of 561.8 mAh/g remained (74.96% retention), with only a very small average capacity decay of 0.056%. The excellent reversibility and stability of the novel sulfur cathode can be attributed to the ability of the boron-doped microporous carbon host to both physically confine polysulfides and chemically bind these species on the host surface. Theoretical calculations confirm that boron-doped carbon is capable of significantly stronger interactions with the polysulfide species than undoped carbon, most likely as a result of the lower electronegativity of boron. We believe that this doping strategy can be extended to other metal-air batteries and fuel cells, and that it has promising potential for many different applications.