The additive of 15-crown-5 for liquid electrolyte for primary Li/CFx cells is proposed. In their presence the cells with 1 M LiBF4 in GBL and 1 M LiPF6 in EC/DMC/EMC are workable at low temperatures. Their discharge capacities are 140 and 110 mAh g− 1 at −45 ÷ −50 °C respectively. The 15-crown-5 additive probably is adsorbed on electrodes surfaces and form Li+ conducting layers. This mechanism approved by quantum-chemical modeling.