What is a lithium battery? What is its core principle?

Lithium battery, fully known as "Lithium-ion Battery", is a type of secondary battery (i.e., rechargeable battery) that operates by reversibly inserting and extracting lithium ions between the positive and negative electrodes.

In simple terms, its working principle can be understood as the "rocking chair model":

During charging: Lithium ions "escape" from the cathode material (such as lithium iron phosphate or lithium cobaltate), pass through the intermediate electrolyte (liquid or solid), and "rock" into the layered structure of the anode material (usually graphite) like sitting in a rocking chair, where they are stored. At this point, the battery stores electrical energy.

During discharge: Lithium ions "run" back from the negative electrode to the positive electrode. In this process, electrons flow from the negative electrode to the positive electrode through the external circuit, generating current to power our devices.

Core components:

Positive electrode: Determines the energy density and voltage of the battery (such as lithium cobalt oxide (LCO), lithium iron phosphate (LFP), and ternary lithium nickel cobalt manganese (NCM)/nickel cobalt aluminum (NCA)).

Negative electrode: The place where lithium ions are stored (such as graphite, silicon-carbon composite materials).

Electrolyte: The "highway" for lithium ion shuttling (liquid electrolyte or solid electrolyte).

Separator: isolates the positive and negative electrodes, preventing short circuits but allowing ions to pass through.