The smallest working unit in a battery is the electrochemical cell, consisting of a cathode and an anode separated and connected by an electrolyte. The electrolyte conducts ions but is an insulator to electrons. In a charged state, the anode contains a high concentration of intercalated lithium while the cathode is depleted of lithium.
The electrodes in lithium-ion 18650 battery cells are always solid materials. One can distinguish between cell types according to their electrolytes, which may be liquid, gel, or solid-state components. The electrolytes in gel and solid-state cells represent a structural component and do not need additional separators for the effective separation of electrodes and avoidance of short circuits.
For low-energy and low-power applications, a cell often represents a full battery. For high-energy and high-power applications such as transportation or stationary storage, a number of cells are packaged in a module, and a number of modules are packaged in a battery.
A lithium polymer lifepo4 battery is rectangular in shape and is very thin. These batteries are used in a variety of devices from laptop computers, cell phones, and other electronic devices. Any battery can explode if over charged but the polymer battery is not as likely to burst into flames like the ion based battery. The polymer battery is what many call a pouch cell design battery. This is what makes it lighter than the ion battery. The polymer battery is designed where the electrode sheet and its separator are laminated onto each other. This eliminates the metal needed in the ion batteries. Another benefit of the polymer battery is that manufactures can shape the cell into any form that is needed for any type of device.
On the other hand, a Polymer Lithium Ion battery is a battery that is heavier in weight than the polymer batteries. It is cheaper in cost and has a longer charge than the lithium polymer battery. The reason that Ion batteries are heavier than that of polymer batteries is that the ion battery has metal in it to hold the electrodes needed for the power. Both the polymer and the ion batteries are rechargeable and can be used over and over.