Abstract: The lithium-boron composite material was prepared by compounding molten metal lithium and high-purity boron powder and applied to solid electrolyte (Li_6.4La₃Zr_1.4Ta_0.6O₁₂, LLZTO) to make the solid-state symme-tric battery. A comparative study of the electrochemical performance of the lithium-boron composite solid-state symmetric battery and the lithium metal solid-state symmetry battery was conducted. The results showed that the interface impedance (about 6 Ω/cm²) of the lithium-boron composite solid-state battery is much smaller than that of the metal lithium solid-state battery (about 103 Ω/cm²), indicating that the lithium-boron composite electrode and the solid electrolyte were in good contact. The test of charge-discharge under the current density of at 400 μA/cm² was carried out. The lithium-boron composite solid-state symmetric battery could be stably cycled for more than 250 times while the metal lithium solid-state battery quickly failed. The critical current density of the lithium-boron composite solid-state symmetric battery at a capacity of 0.1 mAh reached 2 700 μA/cm² and the capacity could reach 12 mAh/cm² under the current density of 0.1 mA/cm². The lithium-boron composite solid-state symmetric battery had excellent cycling performance.