Requirements for negative electrode materials in lithium-ion batteries
As a core component of lithium-ion batteries, the negative electrode material typically needs to meet the following conditions for application:
① The lithium intercalation potential is low and stable to ensure a high output voltage;
② It allows for a greater number of reversible lithium-ion insertions and extractions, resulting in higher specific capacity;
③ The structure is relatively stable during charging and discharging, and it has a long cycle life;
④ High electronic conductivity, ionic conductivity, and low charge transfer resistance ensure low voltage polarization and good rate performance;
⑤ It can form a stable solid electrolyte film with the electrolyte, ensuring high coulombic efficiency;
⑥ The preparation process is simple, easy to industrialize, and inexpensive;
⑦ Environmentally friendly; the materials will not cause serious pollution to the environment during production and actual use.
⑧ Abundant resources, etc.
Classification of lithium-ion battery anode materials
As one of the four key materials for lithium-ion batteries, anode materials have relatively mature technology and market presence. Current research directions for anode materials include: graphitized carbon materials, amorphous carbon materials, nitrides, silicon-based materials, tin-based materials, novel alloys, and other materials.
The first type is carbon anode materials: Currently, the anode materials actually used in lithium-ion batteries are basically carbon materials, such as artificial graphite, natural graphite, mesophase carbon microspheres, petroleum coke, carbon fiber, pyrolytic resin carbon, etc.
The second type is tin-based anode materials: Tin-based anode materials can be divided into two types: tin oxides and tin-based composite oxides. Oxides refer to oxides of metallic tin in various valence states. Currently, there are no commercially available products.
The third type is lithium-containing transition metal nitride anode materials, but there are currently no commercially available products.
The fourth type is alloy-based anode materials: including tin-based alloys, silicon-based alloys, germanium-based alloys, aluminum-based alloys, antimony-based alloys, magnesium-based alloys, and other alloys, none of which are currently commercially available.
The fifth type is nanoscale anode materials: carbon nanotubes and nanoalloy materials.
Applications and Development of Lithium-ion Battery Anode Materials
The energy density of the negative electrode material in a lithium-ion battery is one of the most important factors affecting the battery's overall energy density. The positive electrode material, negative electrode material, electrolyte, and separator are considered the four core materials of a lithium-ion battery. The negative electrode material is the primary storage medium for lithium in a lithium-ion battery, enabling lithium ions to be inserted and extracted during charging and discharging. The negative electrode is where electrons flow out during battery discharge, and its material significantly impacts the initial efficiency and cycle performance of the lithium-ion battery. The performance of the negative electrode material directly affects the overall performance of the lithium-ion battery, accounting for approximately 5-15% of the total cost.
With technological advancements, current lithium-ion battery anode materials have evolved from a single type of artificial graphite to a situation where natural graphite, mesophase carbon microspheres, and artificial graphite are the main materials, while soft/hard carbon, amorphous carbon, lithium titanate, silicon-carbon alloys, and other anode materials coexist.
