Abstract: The Li/CF_x primary battery, with its highest theoretical energy density (about 2180 W·h·kg^-1) among primary batteries made of solid cathode materials, is suitable for the deep space tasks involving strict constraints for the total mass of the probe. A group of Li/CF_x primary batteries is employed to power China’s first Mars exploration probe Tianwen-1 during its EDL stage. In this paper, four basic features of the Li/CF_x primary battery, closely related to the deep space explorations, are emphatically analyzed. The new demands to be covered in the analysis are proposed, and several specialized tests are carried out to further verify the adaptability of the batteries to the Mars exploration tasks. It is shown that the Li/CF_x primary battery is applicable under the low discharging rate and the short-term discharge, with adequate capability of enduring over-charging and over-discharging, and can survive a certain extent of irradiation as well. This kind of batteries should be stored at a low temperature, since its storage life will be severely shortened at temperature of above 65 ℃.