3D-Microbattery Architectural Design Optimization Using Automatic Geometry Generator and Transmission-Line Model

Abstract

Summary Optimization of the 3D battery architecture is crucial to improve the performance of microbatteries. However, such optimization is difficult and time consuming by hand for even experts. In this article, we propose a battery optimization system, which consists of an automatic geometry generator and performance simulators. The geometry generator creates feasible 3D batteries without using any human intuition and experience for the spatial arrangement of positive and negative electrodes. For quick evaluation of the internal resistance, which relates power and energy densities, we propose the transmission line model, the so-called 3D porous electrode model, as one of the performance simulators. To show the effectiveness of the optimization system, we designed the lithium-ion microbatteries. In the trade-off frontier for the internal resistance and the capacity, we successfully found a new battery architecture that has higher power and energy densities over the conventional interdigitated plates configuration.

How to Pack a Punch – Why 3D Batteries are Essential

“…Miyamoto et al [10] . (Figure 8) developed an automatic geometry‐generator algorithm, which designs the full cell on the basis of random sampling by using the size and resolution of the 3D‐battery cell, and the volume ratio of the positive and negative electrodes, as the input data.…”

“…Therefore, computational models can help in the prediction of which 3D architectures are best suited for a given set of active materials and application. [10] Continuum simulations have been carried out by different researchers in order to investigate the influence on the battery performance, of width, length, pitch and end shape of the interdigitated electrodes. [15,[32][33][34][35][36][37][38][39] The finite-element method (FEM) and the finite-volume method (FVM) have been used to simulate ion transport across the battery, which is assumed to be continuous and homogeneous.…”

“…Miyamoto et al [10] (Figure 8) developed an automatic geometry-generator algorithm, which designs the full cell on the basis of random sampling by using the size and resolution of the 3D-battery cell, and the volume ratio of the positive and negative electrodes, as the input data. For rapid computing of the internal resistance of the 3D battery, the authors propose the transmission-line model, equivalent to the 3D porouselectrode model.…”

“…Despite this, several thin‐film MBs have already been commercialized and their applications in IoT devices, such as wireless sensors, renewable‐energy‐storage devices, RFID (radio‐frequency identification) tags, and “smart” cards, have been explored [9] . As mentioned above, the use of thicker electrodes improves the areal energy density, but leads to a lower power density as a result of the increase in the internal resistance [10] . As an example, LiCoO 2 /Li batteries, containing thick sintered cathodes, which had up to 6 mAh.cm −2 areal capacities, suffered from poor mechanical integrity, high overpotentials and short cycle‐life [5,11] …”

“…[9] As mentioned above, the use of thicker electrodes improves the areal energy density, but leads to a lower power density as a result of the increase in the internal resistance. [10] As an example, LiCoO 2 /Li batteries, containing thick sintered cathodes, which had up to 6 mAh.cm À 2 areal capacities, suffered from poor mechanical integrity, high overpotentials and short cycle-life. [5,11] A more advanced 3D architecture is a design, which folds the complete thin-film cell structure from planar geometry into a network placed on a small footprint, so that the overall current path remains short.…”