Lithium Polymer Batteries vs Lithium Batteries
battery concept difference
Lithium batteries are easily confused with the following two types of batteries
(1) Lithium battery: use metal lithium as the negative electrode.
(2) Lithium-ion batteries: use non-aqueous liquid organic electrolytes.
(3) Lithium-ion polymer battery: use polymer to gel liquid organic solvent, or directly use all-solid electrolyte. Lithium-ion batteries generally use graphite-based carbon materials as the negative electrode.
Lithium-based batteries are divided into lithium batteries and lithium-ion batteries. Cell phones and laptops use lithium-ion batteries, commonly known as lithium-ion batteries.
Definition of polymer lithium battery
Lithium-ion batteries that use polymers as electrolytes are called polymer lithium batteries and are subdivided into "semi-polymer" and "full-polymer".
It refers to coating a layer of PVDF polymer on the barrier film to strengthen the adhesion of the hardened cell, and its electrolyte is still a liquid electrolyte.
It refers to the use of polymers to form a gel network inside the cell, and then inject the electrolyte to form an electrolyte. The amount of electrolyte is much smaller than that of "semi-polymer", which greatly improves the safety of lithium-ion batteries. Now only SONY is mass-producing "all-polymer" lithium-ion batteries.
The polymer battery is commonly known as the soft pack battery. This packaging film is composed of three layers of PP, Al and nylon. Because PP and nylon are polymers, this battery is called a polymer battery.
The difference between lithium ion battery and polymer lithium battery
(1) The raw materials are different
The raw material of lithium-ion battery is electrolyte (liquid or colloid);
The raw materials of polymer lithium batteries are electrolytes including polymer electrolytes (solid or colloidal) and organic electrolytes.
(2) Different in terms of security
Lithium-ion batteries are simply blasted in a high temperature and high pressure environment;
The polymer lithium battery uses aluminum-plastic film as the outer casing. When the organic electrolyte is used inside, it will not explode even if the liquid is very hot.
(3) Different shapes
Polymer batteries can be thin, any area, and any shape because their electrolytes can be solid or colloidal rather than liquid.
Lithium batteries use electrolyte, which requires a solid outer casing as a secondary package to contain the electrolyte.
(4) Different cell voltages
Because the polymer battery is made of polymer materials, it can be made into a multi-layer combination in the cell to achieve high voltage, while the nominal capacity of the lithium battery cell is 3.6V.
(5) The production process is different
The thinner the polymer battery, the better the production, and the thicker the lithium battery, the better the production, which makes the lithium battery more widely used.
The capacity of the polymer battery has not been effectively improved, and it has been reduced compared with the standard capacity of the lithium battery.
Advantages of Lithium Polymer Batteries
(1) Good safety performance
In the event of a safety hazard in the polymer lithium battery, the lithium ion battery is simply blasted, while the polymer battery will only be inflated, or at most incinerated.
(2) Small thickness can be made thinner and ultra-thin
The thickness can be less than 1mm, and it can be assembled into a credit card. There is a technical bottleneck when the thickness of ordinary liquid lithium batteries is less than 3.6mm, and the 18650 battery has a standard volume.
(3) Light weight and large capacity
The battery with polymer electrolyte does not need a metal shell as a protective outer packaging, so when the capacity is the same, it is 40% lighter than a steel shell lithium battery and 20% lighter than an aluminum shell battery. When the volume is generally large, the capacity of the polymer battery is larger, about 30% higher.
(4) The shape can be customized
Polymer batteries can add or reduce the thickness of the battery cells. For example, the new Sony notebooks use trapezoidal polymer batteries to make full use of the internal space.
Defects of Lithium Polymer Batteries
(1) High cost
(2) Poor versatility
(3) As long as it is broken, it will be completely useless, and the circuit control needs to be protected. Overcharging or overdischarging will damage the reversibility of the chemical substances inside the battery, which will seriously affect the battery life.
(4) The lifespan is shorter than that of the 18650, because of the use of different designs and materials, some have liquid inside, and some are dry or colloidal, and the performance is not as good as the 18650 cylindrical battery during high current discharge.