Computational Analysis of Scalable Three-Dimensional Electrode and Device Architectures

3-D architectures are electrode and battery configurations that are non-planar configurations and offer the potential for greatly improved performance, particularly in terms of volumetric energy density, compared to traditional planar (1-D along the cell-sandwich and 2-D along the plane of the electrodes) configurations (or their derivatives).^{1, 2}  In this work, we present computational analysis of a novel 3-D electrode and device architecture that we introduced earlier.³ This can potentially provide significant enhancements in energy density.  These designs are expected to be scalable and to operate over length scales that exhibit rapid electron and ion transport.

One of the electrode designs we have explored is shown in Fig. 1 and is based on a photonic crystal design.⁴   The local current collector framework arranged in a 3-D configuration is shown in the bottom right-hand corner of Fig. 1a. We refer to this structure as a 3-D scaffold and these structures can be fabricated from carbon-based or metallic materials. The scaffold is coated conformally with a redox-active electrode material. The resulting porous 3-D electrode is shown in the cut-away sections of Fig. 1a and the entire electrode is shown more clearly in Fig. 1b. The continuous pore volume (Fig. 1b) is a key element for this electrode and is purposely designed to not only be interconnected but also to be minimized. Liquid electrolyte, which fills the pores, will thus have access to all of the redox-active material at a suitable length scale.  A detailed view of how the electrolyte is arranged within a given electrode element is shown in Fig. 1c. This figure also indicates how the electrolyte is continuous through the well-structured electrode architecture leading to low tortuosity.

In this paper, we will present the detailed computational analysis of the transport properties of the 3D cathode architecture described above and also relevant electrochemical/electrical/thermal behavior of a cell composed of this cathode. We will utilize the recent 3D battery simulation software (AMPERES - Advanced MultiPhysics for Electrical and Renewable Energy Storage)⁵for detailed analysis of power/energy density performance of this architecture. We also compare these results with theoretical limits of such 3D structures for a few standard battery chemistries such as LiCoO2 and LiFePO4 and compare with respect to standard planar slurry based electrodes.

Acknowledgements

This research is sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy. Additional support is provided by the Vehicle Technologies Program of EERE office within U. S. Department of Energy.

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