Dual driven asymmetric electrolyte with gradient distributed UPy-CNTs for high-performance lithium metal batteries
Asymmetric electrolytes with both anode and cathode compatibility are promising candidates for high-energy–density batteries and high-safety lithium metal batteries (LMBs). However, the asymmetric electrolyte is still hindered by the complex multi-layer coating process, resulting in multiple internal interfaces of the electrolyte and poor battery performance. Herein, a one-step constructed asymmetric electrolyte with gradient distributions of 2‐ureido‐4[1H]-pyrimidinone functionalized carbon nanotubes (UPy-CNTs) is prepared via the dual driving forces of solvent evaporation and fluoropolymer migration. On the one hand, during the solvent evaporation process, based on the competitive effect between evaporation of solvent and diffusion of dispersions, the gradient distribution of asymmetric electrolyte can be constructed by enhancing evaporation and inhibiting uniform diffusion. On the other hand, due to the abundant hydrogen bonds between UPy and F, the gradient distribution of UPy-CNTs can be further promoted when the fluoropolymer spontaneously migrates to the surface. The gradient distribution of UPy-CNTs not only greatly increases Young’s modulus of the asymmetric electrolyte on the Li metal side, but also can adjust the Li + solvation structure to form a LiF-rich solid electrolyte interface (SEI), thereby inhibiting the generation and growth of lithium dendrites. Because of the ingenious structure of the asymmetric electrolyte, the ionic conductivity is 0.226 mS cm −1 and the Li + transferences number is 0.79. Prominently, Li||Li symmetric batteries can stably cycle for 2500 h at 0.1 mA cm −2 and 0.1 mAh cm −2 . In addition, Li||LFP batteries can maintain a high specific capacity of 146 mAh g −1 after 200 cycles at 0.5C.
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