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Instead of the relatively costly cobalt oxide found in liquid Li-ion cells, cathodes in solid-polymer Li-ion cells use an inexpensive metal oxide. More significantly, every component of a solid-polymer Li-ion cell is fabricated in rolled-sheet form to support exceptionally cost-effective, high-speed, high-volume battery production. Electrodes, electrolyte, and foil packaging are sandwiched together on continuous-feed rolls into finished batteries in one smooth process. In comparison, the winding and canning processes used to produce liquid Li-ion cells are time-consuming as well as expensive. Ultimately, solid-polymer Li-ion batteries will cost in the range of $1 to $2/Wh. (As a point of reference, NiCd batteries, with five decades of manufacturing improvements, cost slightly less than $1/Wh.)
The basic internal structure of a solid-polymer cell can be configured to virtually any size. Solid-polymer Li-ion batteries have outstanding attributes in the essential areas where liquid Li-ion is weakest. Solid-polymer Li-ion cells offer cost-effective materials and construction, demonstrated safety under abuse conditions, environmental acceptability, and virtually limitless flexibility. Every component of the solid-polymer Li-ion system is, as the name suggests, solid, including the electrolyte. There is no liquid that has to be contained by hermetically sealed cell packaging. An ultra-thin laminated foil material, instead of a rigid metal can, can be used to house each cell.
Solid-polymer Li-ion cells can be made as thin as 0.64 mm, approximately 10 times thinner than the thinnest prismatic liquid Li-ion cells. Solid-polymer cells can also be stacked in series and/or parallel to form ultra-thin battery packs with a wide range of voltages and capacities. This design flexibility enables engineers to obtain the required performance from the flattest-profile battery possible
The width and length of solid-polymer Li-ion cells are as flexible as their thickness. Cells can be configured in virtually any size, making solid-polymer Li-ion a stronger candidate than liquid Li-Ion for electric vehicles and other large-cell applications. Even non-rectangular shapes are possible. This size flexibility of solid-polymer batteries supports maximum energy efficiency within a particular battery cavity. With their laminated-foil housing, solid-polymer Li-ion cells are flexible and can be conformed to battery cavities with curved surfaces. In addition, the foil housing material is considerably lighter than the metal used for liquid Li-ion cells. In terms of cost, the solid-polymer Li-ion system also promises advantages.
