Physics

Engineering

Endocrinology

Physical chemistry

Power (physics)

Electrode

Organic chemistry

Inorganic chemistry

Aqueous solution

Chemistry

Materials science

Lithium (medication)

Freezing point

Chemical engineering

Cathode

Electrochemistry

Battery (electricity)

Electrolyte

Medicine

Thermodynamics

Advanced Energy Materials

Lithium‐ion batteries with aqueous electrolytes can be excellent candidates for battery applications at low temperatures. In contrast to a common misconception, aqueous lithium ion batteries can operate at several tens of degrees below the freezing point of water when high concentration electrolyte solutions are utilized. Furthermore, it is reported here that the performance of intercalation cathodes in aqueous electrolytes is quite remarkable and superior to that in common organic electrolytes at very low temperatures down to about −40 °C. Here in the performance of water‐based electrolyte solutions‐based on three low‐cost inorganic salts (LiNO 3 , Li 2 SO 4 , and LiCl) and that of the corresponding aqueous battery systems is studied in order to understand the rate‐limiting step at sub‐zero temperatures. It is found that the charge transfer resistance is the largest impedance contributor at low temperatures. However, layered cathodes in aqueous electrolytes do not exhibit a significant increase in the charge‐transfer resistance, or a reduction in the accessible capacity during charging until the temperature is close to the solution freezing point. This is in sharp contrast to their behavior in organic electrolytes that do not support any performance below −20 °C. This different behavior explains the dramatically superior performance of lithium ion battery cathodes in water‐based electrolytes at lower temperatures.

Understanding the Exceptional Performance of Lithium‐Ion Battery Cathodes in Aqueous Electrolytes at Subzero Temperatures