what's lithium battery?

Lithium ion battery is a chemical battery that stores and releases electrical energy by moving lithium ions between positive and negative electrodes. It has the characteristics of high energy density and repeatable charging and discharging, and is an important energy storage solution in modern electronic devices and new energy fields.

 

1、 The working principle of lithium batteries

The working principle of lithium batteries is based on the reversible insertion and extraction of lithium ions between positive and negative electrode materials:

Charging process: Lithium ions are extracted from the lattice of the positive electrode material (such as lithium cobalt oxide), inserted into the lattice of the negative electrode material (such as graphite) after passing through the electrolyte, making the negative electrode highly rich in lithium and the positive electrode poor in lithium. 

Discharge process: Lithium ions are released from the lattice of the negative electrode material, re-embedded into the lattice of the positive electrode material after passing through the electrolyte, making the positive electrode rich in lithium and the negative electrode poor in lithium.

The reciprocating motion of lithium ions enables the storage and release of electrical energy. The difference in potential between the positive and negative electrode materials relative to metallic lithium during insertion and extraction of lithium ions is the operating voltage of the battery.


2、 The main components of lithium batteries
Lithium batteries are mainly composed of the following core components:

 Component
 Materials and functions
Positive electrode material
 Lithium cobalt oxide, lithium manganese oxide, nickel cobalt manganese oxide (ternary), lithium iron phosphate, etc., determine battery capacity and voltage
Negative electrode material
 Graphite or carbon materials with structures like graphite, affect battery efficiency and cycling performance
Electrolyte Liquid (carbonate solvent for dissolving lithium hexafluorophosphate) or polymer gel, responsible for ion transport
Membrane Special polymer film that allows lithium ions to pass through but prevents electrons from passing through, ensuring safe isolation
Shell Steel shell, aluminum shell or aluminum-plastic film (flexible packaging), providing mechanical protection and positive and negative terminal leads


3、 The main types of lithium batteries

Lithium batteries are mainly divided into two categories:

(1)  Classified by chemical system

Lithium metal battery: using metallic lithium as the negative electrode, non rechargeable
Lithium ion battery: using lithium compounds as positive electrodes and carbon materials as negative electrodes, capable of repeated charging and discharging

(2) Classification of lithium-ion batteries:

LiCoO₂ , LiMn₂O₄, NMC (Lithium nickel cobalt manganese oxide) , LiFePO₄

(3) Classified by physical structure

Lithium ion battery: liquid electrolyte, metal shell (cylindrical/square)
Lithium polymer battery: solid/gel electrolyte, aluminum plastic film flexible packaging, flexible design

4、 Advantages and disadvantages of lithium batteries

Advantages:
- High energy density: storing more electrical energy per unit weight or volume (180-300Wh/kg).
- Lightweight: Only one-third the weight of lead-acid batteries under the same capacity
- Long cycle life: up to 500-2000 charge and discharge cycles (lead-acid batteries only 300-500 cycles).
- No memory effect: can be charged at any time without affecting capacity.
- Low self discharge rate: The monthly self discharge rate is about 1-2%, much lower than that of nickel hydrogen batteries.


Disadvantages:
- High cost: 2-4 times the price of lead-acid batteries.
- Safety hazards: Overcharging, short circuit, or high temperature may cause uncontrolled heating or even fire.
- Working temperature limit: Poor low-temperature performance, prone to decomposition at high temperatures.
- Circuit protection required: must prevent overcharging/overdischarging.

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