Lithium polymer batteries are those which are developed technologically from lithium ion batteries are known as lithium polymer batteries. Actually, as in the lithium ion design, the lithium salt electrolyte is not placed in the organic solvent. Instead, it is held in a solid polymer composite like polyethylene oxide or polyacrylonitrile.

There are many advantages of Li-poly over Lithium ion. One such advantage is it takes low cost and is affordable. Another advanatage is that it is more robust to physical damage. Since 1996, lithium ion polymer batteries started coming in consumer electronics. Older lithium ion cells had a totally different design from the cells of today. The differences are many. One of the difference is that lithium ion cells or prismatic cells have a rigid metal case whereas polymer cells have a flexible, foil type case but still consist organic solvent.

In lithium ion, the electrodes are being pressed by the rigid case and the separator on to each other. But on the other side, in polymer cells, electrode sheets and the separator sheets are shielded on to each other, therefore, making the external pressure not so necessary.