Lithium is the lightest metal element with high chemical reactivity and strong electrical conductivity. Medical field: Lithium salts (such as lithium carbonate) are often used to treat manic-depressive disorder (bipolar disorder) and depression. Lithium can stabilize mood and help reduce the frequency and intensity of manic and depressive episodes. Battery technology: Lithium-ion batteries are the core technology of modern portable electronic devices and electric vehicles. The lightness and high energy density of lithium make it an ideal choice for battery materials and are widely used in mobile phones, laptops, electric vehicles, etc. Synthetic chemistry: Lithium compounds can be used as reagents in organic synthesis, especially in organic lithium compounds (such as Grignard reagents). They play an important role in synthetic chemical reactions and can be used for the formation of carbon-carbon bonds. Metallurgical field: Lithium compounds act as fluxes in the preparation of alloys, which can improve the physical and chemical properties of metals and are often used in the production of aluminum and magnesium alloys.