Polymer lithium batteries generally refer to lithium polymer batteries, also known as high-molecular lithium batteries, which are a type of chemical battery. Compared to previous batteries, they are characterized by high energy density, miniaturization, and lightweight design.
A lithium polymer battery is a battery system in which at least one or more of the three key components (electrode, electrolyte, and cathode) are made of polymer materials. In lithium polymer battery systems, polymer materials are mostly used in the positive electrode and the electrolyte. The positive electrode material is a conductive polymer or an inorganic compound used in typical lithium-ion batteries, while the negative electrode often uses lithium metal or lithium-carbon intercalation compounds. The electrolyte is a solid or colloidal polymer electrolyte or an organic electrolyte. Because lithium polymer batteries do not contain excess electrolyte, they are more reliable and stable.
Working principle of polymer lithium batteries
Lithium-ion batteries are classified into two types: liquid lithium-ion batteries (LIB) and lithium polymer batteries (PLIB). Liquid lithium-ion batteries are secondary batteries that use Li+ intercalation compounds as both the positive and negative electrodes. The positive electrode uses lithium compounds such as LiCoO2, LiNiO2, or LiMn2O4, and the negative electrode uses the lithium-carbon intercalation compound LixC6. A typical battery system is as follows:
(-) C | LiPF6—EC+DEC | LiCoO2 (+)
Positive electrode reaction: LiCoO2 = Li1-xCoO2 + xLi+ + xe-
Negative electrode reaction: 6C + xLi+ + xe- = LixC6
Overall battery reaction: LiCoO2 + 6C = Li1-xCoO2 + LixC6
The principle of lithium polymer batteries is the same as that of liquid lithium batteries, the main difference being the electrolyte. The main components of a battery include a positive electrode, a negative electrode, and an electrolyte. A lithium polymer battery is defined as one in which at least one of these three components uses a polymer material as the primary battery system. In developed lithium polymer battery systems, polymer materials are mainly used in the positive electrode and the electrolyte.
The positive electrode material includes conductive polymer or inorganic compounds used in general lithium-ion batteries. The electrolyte can be a solid or colloidal polymer electrolyte or an organic electrolyte. General lithium-ion technology uses liquid or colloidal electrolytes, so a robust secondary packaging is required to contain the flammable active ingredients, which increases the weight and also limits the flexibility of size.
The new generation of lithium polymer batteries theoretically allows for diverse shapes, increasing the flexibility of battery design. This enables the creation of batteries with various shapes and capacities to meet product requirements, providing application device developers with a high degree of design flexibility and adaptability in power solutions to maximize product performance. Simultaneously, lithium polymer batteries offer 10% higher energy density than conventional lithium-ion batteries. Their capacity and cycle life are also significantly improved compared to lithium-ion batteries.
