Atom interferometer enables high-precision measurement of recoil frequency, which is crucial for determining the fine structure constant. Large momentum transfer (LMT) based on Bloch oscillations in atom interferometers can significantly enhance the measurement precision of the recoil frequency. Typically, applying Bloch oscillations to an atomic ensemble requires the atoms to be cooled within the first Brillouin zone. However, deep cooling of lithium atoms is challenging, making it difficult to directly apply Bloch oscillations. Therefore, this paper develops an LMT technique based on Bloch oscillations in a relatively high-temperature ensemble of
6Li atoms. By constructing a deep potential optical lattice, the high-temperature atoms can be efficiently loaded into the lattice. Subsequently, the optical lattice is adiabatically chirped to suppress interband transitions of the atoms, thereby enabling them to accelerate with the lattice. Although the efficiency of a single Bloch oscillation decreases under the tight-binding approximation, this method simultaneously relaxes the temperature requirements of the LMT technique. Consequently, we achieve a large momentum transfer of 40 recoil momentum at 80 μK (far above the recoil temperature), with the number of transferred atoms reaching up to 5×10
6. Subsequent analyses of the atomic momentum spectrum before and after the Bloch oscillations reveal that due to Doppler broadening, the atomic momentum shows a continuous distribution between the initial momentum and the target momentum, which limits the momentum transfer efficiency. It is found that for a fixed optical lattice depth and pulse duration, the momentum distribution of atoms participating in the Bloch oscillations is independent of the number of oscillations. Furthermore, atoms with initial velocities aligned with the acceleration direction of the optical lattice are more easily accelerated. This LMT technique is expected to substantially enhance the measurement precision of the
6Li atomic recoil frequency, providing an important reference for subsequent high-precision calibration of the fine structure constant using
6Li atom interferometers.