Meaning
Electrochemical cells utilize solid-phase materials rather than liquid solvents to conduct ions between the anode and cathode. By incorporating a solid state electrolyte, battery designs can eliminate volatile and flammable organic solvents, which significantly improves safety. This technology enables the use of high-energy lithium metal anodes.
Ionic Transport
Lithium ions migrate through the crystal lattice or polymer chain network via vacuum vacancies or interstitial pathways. In a solid state electrolyte, the ionic conductivity can match or exceed that of liquid electrolytes, but it requires highly ordered structures. Ceramic solid electrolytes, like oxides and sulfides, have high lithium-ion conductivity at room temperature.
Polymer electrolytes, on the other hand, require elevated temperatures to achieve comparable ion mobility.
Sourcing Benefit
Battery procurement teams target this technology to secure high-safety and high-energy cells. Because a solid state electrolyte is non-flammable, it reduces the need for heavy and expensive thermal management systems in the battery pack. Sourcing managers look at the long-term price projections of these materials to decide when to transition from standard lithium-ion cells.
This transition can reduce the overall weight of the vehicle and increase driving range.
Manufacturing Challenge
Maintaining intimate solid-to-solid contact at the interfaces is difficult over long cycle life. As the electrodes expand and contract during charge and discharge, the solid state electrolyte can detach, which increases the internal impedance. To mitigate this issue, cell designs must incorporate protective layers or run under high physical pressure.
Sourcing teams must evaluate the cost and feasibility of the pressure-applying mechanisms required for these battery packs.
