Strictly speaking, lithium batteries are divided into two types: lithium metal batteries and lithium-ion batteries. This is defined based on the form in which lithium exists. Lithium metal batteries use metallic lithium as electrodes, while lithium-ion batteries use lithium ions as electrodes.
Lithium metal batteries generate electricity through the corrosion or oxidation of metallic lithium. They are unusable once depleted and cannot be recharged, hence the name "primary battery." Lithium-ion batteries, on the other hand, utilize the concentration gradient of lithium ions for energy storage and discharge. Since they do not contain metallic lithium, they are called "secondary lithium batteries." Currently, rechargeable lithium batteries used in mobile phones, cameras, power tools, electric vehicles, energy storage, and communication base stations are all lithium-ion batteries. Most commonly seen lithium batteries on the market are lithium-ion batteries, and are often simply referred to as lithium batteries. This article primarily refers to lithium-ion batteries.
I. Classification of Lithium Batteries
1. Two common classification methods in the market: classification by electrode material and classification by product appearance.
A. Classification by electrode material
Cathode materials: Lithium iron phosphate (LFP), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), (binary batteries: lithium nickel manganese oxide/lithium nickel cobalt oxide), (ternary batteries: lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA))
Anode materials: Lithium titanate (LTO) batteries, graphene batteries, carbon nanofiber batteries
The concept of graphene in the market mainly refers to graphene-based batteries, which involve adding graphene slurry to the electrodes or adding a graphene coating to the separator. Lithium nickel oxide and magnesium-based batteries are basically non-existent in the market.
B. Classification by product appearance
They are categorized into: cylindrical, soft-pack, and square.
Cylindrical and square outer packaging is mostly made of steel or aluminum. Soft-pack packaging is made of aluminum-plastic film. In fact, soft-pack is also a type of square, but in the market, those packaged with aluminum-plastic film are commonly referred to as soft-pack, and some people also call soft-pack batteries polymer batteries.
For cylindrical lithium-ion batteries, the model number is generally a 5-digit number. The first two digits represent the battery's diameter, and the middle two digits represent its height. The unit is millimeters. For example, an 18650 lithium battery has a diameter of 18 millimeters and a height of 65 millimeters.
C. According to the different electrolyte materials
Lithium-ion batteries are classified into liquid lithium-ion batteries (LIB) and polymer lithium-ion batteries (PLB).
Liquid lithium-ion batteries use liquid electrolytes (most current power batteries use this type). Polymer lithium-ion batteries use solid polymer electrolytes instead; these polymers can be in a "dry" or "gel" state, but most currently use polymer gel electrolytes. Strictly speaking, solid-state batteries refer to batteries where both the electrodes and electrolyte are solid.
D. Classification by battery practical performance
There are power batteries and energy batteries. Energy batteries are characterized by high energy density and are mainly used for high energy output; power batteries are characterized by high power density and are mainly used for instantaneous high power output. Power-energy type lithium batteries emerged with the advent of plug-in hybrid electric vehicles. They require high energy storage to support a certain distance of pure electric driving, and also need good power characteristics to switch to hybrid mode when the battery is low.
Simply put, energy-type sprinters are like marathon runners; they need endurance, which means they require high capacity, but they don't have high requirements for high current discharge performance. Power-type sprinters, on the other hand, rely on explosive power, but they also need endurance, otherwise they won't be able to go far if their capacity is too small.
II. Composition of Lithium-ion Battery Materials
The four main materials are: positive electrode material, negative electrode material, separator, and electrolyte.
Auxiliary materials: NMP, copper foil, aluminum foil, aluminum shell cover, conductive agent, adhesive, others (EMD), etc.
III. Manufacturing Process
The manufacturing process of lithium batteries can be divided into four main steps: electrode fabrication, cell assembly, activation and testing, and battery assembly. Electrode fabrication includes the production of positive and negative electrode sheets, and the main steps include material preparation, mixing, coating, rolling, slitting, and tab fabrication.
IV. Equipment Required for Production
According to the lithium-ion battery production process, lithium battery equipment can be mainly divided into front-end equipment, mid-end equipment and back-end equipment.
The front-end equipment primarily targets the electrode fabrication process, including vacuum mixers, coating machines, rolling mills, and slitting machines. The coating process requires uniformly applying the stirred slurry to the metal surface with a thickness accurate to less than 3μm. Slitting must ensure that the sliced surfaces are free of any burrs, otherwise it will significantly impact subsequent processes. Therefore, the front-end equipment is the core equipment in battery manufacturing, directly affecting the quality of the entire production line.
Mid-range equipment mainly covers the cell assembly process, including winding or stacking machines, cell casing machines, liquid injection machines, and sealing welding equipment.
Back-end equipment mainly covers processes such as cell activation and formation, capacity testing, and assembly into battery packs. In contrast, mid- and back-end equipment, such as casing, sealing, and testing machines, are relatively simple and have lower technical requirements.
V. Applications of Lithium Batteries
It is mainly divided into three categories: digital products, power products, and energy storage products.
Digital products: mobile phones, tablets, laptops, electric toys, MP3/MP4 players, headphones, power banks, model airplanes, portable power banks, etc.
Power-related: mainly refers to electric vehicles, such as electric bicycles and new energy vehicles.
Energy storage: mainly used in base station power supplies, clean energy storage, grid power storage, and home photovoltaic storage systems.
It is believed that lithium batteries will have a wider range of applications in the future.
