Working Principle of Lithium-Ion Batteries

Although lithium-ion batteries may sound sophisticated, their working principle is essentially straightforward. What is commonly referred to as "lithium batteries" in daily discourse generally denoteslithium-ion batteries, which serve as the core power source for new energy vehicles.

In brief, a lithium-ion battery comprises four key components: the cathode, anode, electrolyte, and polymer separator. The cathode is composed of lithium alloy metal oxide, while the anode is made of graphite, with the separator positioned between them to isolate the two electrodes. The separator plays a critical role: it permits only the passage of lithium ions while blocking electrons. The electrolyte, meanwhile, functions as a transport medium for lithium ions, facilitating their unimpeded movement between the cathode and anode.

Discharging Process (During Operation)

When the battery supplies power to drive the motor, lithium ions migrate from the anode, pass through the separator, and move toward the cathode. Electrons, being blocked by the separator, are compelled to flow from the anode to the cathode via an external circuit, thereby forming an electric current that powers the motor. This process can be analogized to a relay race: lithium ions act as the "athletes", the separator serves as the "referee", and electrons behave as "spectators" that can only transfer energy through the external circuit.

Charging Process (During Charging)

During the charging phase, lithium ions are extracted from the cathode, traverse the electrolyte and separator, and intercalate into the carbon layers of the anode. The carbon layers possess a porous structure, and the higher the intercalation capacity of lithium ions, the greater the battery's energy storage capacity. Simultaneously, external electrons flow from the cathode to the anode through the charger, completing the current compensation. This process resembles "rocking" lithium ions from one electrode to the other, hence lithium-ion batteries are vividly termed "rocking-chair batteries".

In summary, the working principle of lithium-ion batteries revolves around the reversible migration of lithium ions between the cathode and anode, with electrons forming an electric current through the external circuit. Characterized by high efficiency and environmental friendliness, lithium-ion batteries have undoubtedly become the "core power unit" of new energy vehicles.