Abstract: The spent cathode materials from ternary lithium-ion batteries contain key metal elements such as lithium, nickel, cobalt, and manganese, and have extremely high recovery value. The reduction roasting and priority lithium extraction process, due to its short process and high efficiency, has become one of the key technologies for the resource recovery of spent ternary lithium-ion batteries. However, most of the existing process routes suffer from high energy consumption, secondary pollution, or low metal recovery rates, creating an urgent need for the development of green and low-carbon novel recovery technologies. As a renewable energy source, biomass presents an effective green and low-carbon approach for reduction roasting and priority lithium extraction. Therefore, this study used actual biomass materials for pyrolysis gas reduction roasting experiments. The reducing effects of pyrolysis gases from three biomass materials—poplar sawdust, peanut shells, and tea residues—on the cathode material and the water-leaching lithium recovery efficiencies from the roasted products were compared. The optimal roasting conditions for both poplar sawdust and peanut shell pyrolysis gases were 600 °C for 30 minutes. Under these optimal conditions, the lithium leaching rates from the roasted products were 95.67% and 93.38%, respectively. Under the synergistic effect of multiple components, tea residue pyrolysis gas exhibited better leaching efficiency in a shorter time; its optimal roasting conditions were 600 °C for 20 minutes, achieving a lithium leaching rate of 94.70% from the roasted product under these conditions. On this basis, and informed by thermogravimetric and differential scanning calorimetry analyses of the electrode material, reduction roasting experiments using tea residue pyrolysis gas were conducted. The results showed that the presence of CO₂ in the tea residue pyrolysis gas effectively avoided the formation of LiAlO₂. However, the presence of the organic binder delayed the optimal roasting time to 30 minutes and caused a slight decrease in lithium leaching efficiency. Under the optimal conditions （600 °C, 30 minutes）, the lithium leaching rate reached 91.25%. Further evaporation and crystallization of the lithium-rich leachate produced a lithium carbonate product with a rod-like microstructure. XRD analysis indicated that the peaks of the evaporated and crystallized product fully matched the characteristic peaks of lithium carbonate, and the purity of the lithium carbonate product reached 99.7%.