17. Macromodeling of Microbatteries for IoT Micropower Source Integration

Thin-film, solid-state microbatteries represent a viable alternative for powering small form-factor IoT microsystems or storing the power harvested by energy microsensors. One major obstacle to their widespread use in integrated IoT systems has been the absence of a high-fidelity, physics-based, compact model describing their operation and enabling their design and verification in the same CAD environment as integrated power management systems. In this chapter, we develop and validate such models using a thorough analysis of the electrochemistry of a thin-film, solid-state, lithium-ion microbattery. One of our compact models is based on a behavioral linearization step where the nonlinear partial differential equations (PDEs) describing the microbattery electrochemistry are replaced with linear ones without virtually any loss in accuracy. We then apply the well-established methodology of Arnoldi-based model order reduction (MOR) techniques to develop a compact microbattery model capable of reproducing its input-output electrical behavior with less than 1% error with respect to the full nonlinear PDEs. The use of MOR results in more than 30X speedup in transient simulation.