Thin-film lithium-ion battery

The thin film lithium-ion battery is a form of solid-state battery. Its development is motivated by the prospect of combining the advantages of solid-state batteries with the advantages of thin-film manufacturing processes. Thin-film construction could lead to improvements in specific energy, energy density, and power density on top of the gains from using a solid electrolyte. It allows for flexible cells only a few microns thick. It may also reduce manufacturing costs from scalable roll-to-roll processing and even allow for the use of cheap materials. Lithium-ion batteries store chemical energy in reactive chemicals at the anodes and cathodes of a cell. Typically, anodes and cathodes exchange lithium (Li+) ions through a fluid electrolyte that passes through a porous separator which prevents direct contact between the anode and cathode. Such contact would lead to an internal short circuit and a potentially hazardous uncontrolled reaction. Electric current is usually carried by conductive collectors at the anodes and cathodes to and from the negative and positive terminals of the cell (respectively). In a thin-film lithium battery the electrolyte is solid and the other components are deposited in layers on a substrate. In some designs, the solid electrolyte also serves as a separator. Cathode materials in thin film lithium ion batteries are the same as in classical lithium ion batteries. They are normally metal oxides that are deposited as a film by various methods. Metal oxide materials are shown below as well as their relative specific capacities (Λ), open circuit voltages (Voc), and energy densities (DE). There are various methods being used to deposit thin film cathode materials onto the current collector. In Pulsed Laser Deposition, materials are fabricated by controlling parameters such as laser energy and fluence, substrate temperature, background pressure, and target-substrate distance. In Magnetron Sputtering the substrate is cooled for deposition. In Chemical Vapor Deposition, volatile precursor materials are deposited onto a substrate material.