A lot of mythology surrounds the electrolyte. Surely it should be a concentrated solution of KOH but how much? Research shows that different concentrations bestow different benefits. For example 1.25 g/mL of KOH in distilled water gives the longest life, while 1.34 g/mL gives the highest output and greatly helps the cells resist freezing in cold climates. This is good to know when using these cells “off the grid” in Northern climes.

The electrolyte mixture of potassium hydroxide and lithium hydroxide is not consumed during charging or discharging, so unlike a lead-acid battery the electrolyte specific gravity does not indicate state of charge. It will not change under normal operations except through evaporation.

Lithium hydroxide improves the performance of the modern cell but there is a popular misconception that this adds to the cell’s capacity. In actuality, lithium hydroxide decreases the cell’s capacity, somewhat. However, it has a protective effect on the cell during conditions of high temperature cycling and high loads.

If you choose to use KOH and LiOH, the mixture that seems to perform best is:
A. KOH (Potassium hydroxide) 300 g/L
B. LiOH (Lithium hydroxide) 15 g/L

If you can’t get lithium hydroxide, you might try disassembling an AA size energizer ultimate lithium battery to reveal a thin sheet of lithium metal. It reacts readily with distilled water to form the hydroxide. BE CAREFUL. It may spontaneously combust!