The metal lithium is produced by the electrolysis of molten lithium chloride and potassium chloride.
Here's a more detailed explanation:
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Source of Lithium: Most lithium is sourced from brines, particularly in Chile, where lithium carbonate is obtained by treating the brines with sodium carbonate.
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Preparation of Lithium Chloride: The lithium carbonate is then converted into lithium chloride (LiCl), which is essential for the next step.
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Electrolysis Process:
- Lithium chloride is mixed with potassium chloride (KCl) to lower the melting point of the electrolyte. This reduces the energy needed for electrolysis.
- The molten mixture is then subjected to electrolysis.
- During electrolysis, lithium ions (Li+) are reduced at the cathode (negative electrode) to form lithium metal (Li).
- Chlorine ions (Cl-) are oxidized at the anode (positive electrode) to form chlorine gas (Cl2).
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Chemical Reactions:
- At the Cathode (Reduction): Li+ + e- → Li
- At the Anode (Oxidation): 2Cl- → Cl2 + 2e-
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Why Electrolysis? Lithium is a highly reactive metal. Electrolysis of the molten salt is necessary because:
- It's challenging to reduce lithium ions via chemical reducing agents due to lithium's strong electropositive nature.
- Electrolysis provides the necessary energy to overcome the stability of the lithium ion.
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Handling and Storage: Lithium metal produced through electrolysis is highly reactive and must be protected from air and moisture to prevent rapid oxidation or combustion. It is typically stored under mineral oil.
In summary, lithium metal is extracted from sources like brines, converted into lithium chloride, and then isolated through the electrolysis of a molten lithium chloride and potassium chloride mixture. This process takes advantage of the electrochemical properties of lithium to produce the pure metal.
