Anode-free lithium-ion batteries offer a volumetric energy density approximately 60% higher than that of conventional lithium-ion cells. Despite this advantage, they often experience rapid capacity degradation and a limited cycle life. Optimizing electrolyte formulations—particularly through the use of specific additives, solvents, and lithium salts—is essential to improving these systems. This study explores electrolytes composed of fluorinated and carbonate-based solvents applied in anode-free lithium-ion cells featuring copper as the anode substrate and Li_1.05Ni_0.33Mn_0.33Co_0.33O₂ as the cathode. In the present work, the ionic conductivity of electrolytes was studied by impedance spectroscopy, and the electrochemical parameters of anode-free lithium-ion cells were compared using these electrolyte solutions: lithium difluoro(oxalato)borat (LIDFOB) salts were used in a mixture of solvents such as fluoroethylene carbonate (FEC) and dimethoxyethane (DME) in a ratio of 3:7 and in a mixture of propylene carbonate (PC) and dimethoxyethane in a ratio of 3:7. Enhanced performance was observed upon the substitution of conventional carbonates with fluorinated co-solvents. The findings suggest that LiDFOB is a thermostable salt, and its high conductivity contributes to the formation and stabilization of the interface of solid electrolytes. The results indicate that at low temperature conditions, a double salt should be used for lithium current sources, for example, 0.4 M LiDFOB and 0.6 M LiBF₄, as well as electrolyte additives such as fluoroethylene carbonate and lithium nitrate.

Primary lithium/carbon monofluoride (Li/CFₓ) batteries are widely recognized for their high theoretical energy density, long shelf life, and low self-discharge, making them ideal for aerospace, medical, and military applications. However, their performance at low temperatures is severely limited due to increased interfacial resistance and reduced lithium-ion transport. In this study, we investigate the effect of electrolyte composition on the ionic conductivity and discharge behavior of Li/CFₓ cells under –20 °C conditions. A series of electrolyte systems was evaluated, including single-salt and dual-salt formulations based on LiDFOB, LiBF₄, LiPF₆, and LiClO₄ in various solvent mixtures (PC:DME, FEC:DME, and PC:DME:EA), with and without additives such as fluoroethylene carbonate (FEC) and lithium nitrate (LiNO₃). Electrochemical impedance spectroscopy revealed that only dual-salt systems and selected additive combinations maintained conductivity above 5 mS/cm at sub-zero temperatures. The best performance was achieved with 0.4 M LiDFOB + 0.6 M LiBF₄ in PC:DME, which exhibited the highest conductivity and a specific discharge capacity of ~220–230 mAh/g. These results demonstrate the critical role of electrolyte optimization in enabling reliable low-temperature performance. Comparative analysis with literature data further confirms the effectiveness of the proposed formulations. This work provides practical guidance for designing advanced electrolytes for primary Li/CFₓ batteries operating in cold environments.

Primary lithium/carbon monofluoride (Li/CFₓ) batteries are widely recognized for their high theoretical energy density, long shelf life, and low self-discharge, making them ideal for aerospace, medical, and military applications. However, their performance at low temperatures is severely limited due to increased interfacial resistance and reduced lithium-ion transport. In this study, we investigate the effect of electrolyte composition on the ionic conductivity and discharge behavior of Li/CFₓ cells under –20 °C conditions. A series of electrolyte systems was evaluated, including single-salt and dual-salt formulations based on LiDFOB, LiBF₄, LiPF₆, and LiClO₄ in various solvent mixtures (PC:DME, FEC:DME, and PC:DME:EA), with and without additives such as fluoroethylene carbonate (FEC) and lithium nitrate (LiNO₃). Electrochemical impedance spectroscopy revealed that only dual-salt systems and selected additive combinations maintained conductivity above 5 mS/cm at sub-zero temperatures. The best performance was achieved with 0.4 M LiDFOB + 0.6 M LiBF₄ in PC:DME, which exhibited the highest conductivity and a specific discharge capacity of ~220–230 mAh/g. These results demonstrate the critical role of electrolyte optimization in enabling reliable low-temperature performance. Comparative analysis with literature data further confirms the effectiveness of the proposed formulations. This work provides practical guidance for designing advanced electrolytes for primary Li/CFₓ batteries operating in cold environments.