Lithium titanate battery discharge principle
A lithium titanate battery consists of positive and negative plates (the positive electrode active material is ternary lithium, and the negative electrode is lithium titanate), a separator, an electrolyte, tabs, and a stainless steel (aluminum alloy) casing. The positive and negative plates are the regions where electrochemical reactions occur, the separator and electrolyte supply the lithium transport channels, and the tabs serve to guide the current.
During battery charging, Li+ ions migrate from the ternary lithium material to the crystal surface, escape from the positive electrode material, and enter the electrolyte under the influence of the electric field. They then pass through the separator and migrate through the electrolyte to the surface of the negative electrode lithium titanate crystal, where they embed into the spinel structure of the negative electrode. Simultaneously, electrons flow through the aluminum foil of the positive electrode, through the tabs, battery terminals, load, negative electrode terminal, and negative tabs to the aluminum foil electrode of the negative electrode, and then through the conductor to the lithium titanate negative electrode, thus achieving charge balance.
During battery discharge, Li is extracted from the lithium titanate spinel structure material, enters the electrolyte, passes through the separator, and then migrates through the electrolyte to the surface of the ternary lithium crystal, where it is then re-intercalated into the ternary lithium material. Simultaneously, electrons flow through the conductor to the negative electrode (aluminum foil electrode), through the tab, the negative terminal, the load, the positive terminal, and the positive tab to the positive electrode (aluminum foil electrode), and then through the conductor to the ternary lithium positive electrode, thus achieving charge balance.
Advantages and disadvantages of lithium titanate batteries
Advantages:
Replacing gasoline-powered vehicles with electric vehicles is the best option for addressing urban environmental pollution, and lithium-ion batteries have attracted widespread attention from researchers. To meet the requirements of electric vehicles for onboard lithium-ion batteries, developing anode materials with high safety, good rate performance, and long lifespan is both a hot topic and a challenge.
Commercial lithium-ion batteries primarily use carbon materials as the negative electrode, but lithium-ion batteries using carbon as the negative electrode still have some drawbacks in use:
1. Overcharging can easily cause lithium dendrites to precipitate, leading to a short circuit in the battery and affecting the safety performance of lithium-ion batteries;
2. It easily forms an SEI film, resulting in lower initial charge/discharge efficiency and larger irreversible capacity;
3. Carbon materials have a lower plateau voltage (close to that of metallic lithium) and are prone to electrolyte analysis, which can lead to safety hazards.
4. The volume changes significantly during lithium-ion insertion and extraction, resulting in poor cycle stability.
Compared with carbon materials, spinel-type Li4Ti5O12 has distinct advantages:
1. It is a zero-strain material with good cyclic performance;
2. The discharge voltage is stable, and the electrolyte does not decompose, improving the safety performance of lithium-ion batteries;
3. Compared with carbon anode materials, lithium titanate has a high lithium-ion diffusion coefficient (2*10-8 cm2/s) and can be charged and discharged at high rates.
4. Lithium titanate has a higher potential than pure metallic lithium and is less prone to lithium dendrite formation, which lays the foundation for ensuring a safe supply of lithium-ion batteries.
shortcoming:
1. Compared to other types of lithium-ion power batteries, the energy density is lower.
2. Gas buildup has been a persistent problem hindering the use of lithium titanate batteries.
3. The price of lithium-ion power batteries is relatively high compared to other types.
