Ultrahigh-Capacity and Scalable Architected Battery Electrodes via Tortuosity Modulation

Abstract

A thick electrode with high areal capacity is a straightforward approach to maximize the energy density of batteries, but the development of thick electrodes suffers from both fabrication challenges and electron/ion transport limitations. In this work, a low-tortuosity LiFePO4 (LFP) electrode with ultrahigh loadings of active materials and a highly efficient transport network was constructed by a facile and scalable templated phase inversion method. The instant solidification of polymers during phase inversion enables the fabrication of ultrathick yet robust electrodes. The open and aligned microchannels with interconnected porous walls provide direct and short ion transport pathways, while the encapsulation of active materials in the carbon framework offers a continuous pathway for electron transport. Benefiting from the structural advantages, the ultrathick bilayer LiFePO4 electrodes (up to 1.2 mm) demonstrate marked improvements in rate performance and cycling stability under high areal loadings (up to 100 mg cm–2). Simulation and operando structural characterization also reveal fast transport kinetics. Combined with the scalable fabrication, our proposed strategy presents an effective alternative for designing practical high energy/power density electrodes at low cost.

Microstructure and mechanical properties of electrochemically cycled ice‐templated Li 4 Ti 5 O 12 sintered anodes

“…First, to achieve reliable mechanical compression measurements, pellets at least 2 mm thick were desired, thus the LTO electrodes evaluated were 2 mm thick. At such great thicknesses, the ion transport was restrictive in the cell due to the extended path lengths, even with the ice‐templated aligned open pores 9 . The charge and discharge current applied was ~1.3 mA, corresponding to ~1.0 mA cm −2 (C/50 based on the LCO gravimetric capacity assumptions).…”

“…At such great thicknesses, the ion transport was restrictive in the cell due to the extended path lengths, even with the ice-templated aligned open pores. 9 The charge and discharge current applied was $1.3 mA, corresponding to $1.0 mA cm À2 (C/50 based on the LCO gravimetric capacity assumptions). The resulting first discharge gravimetric capacity of LCO was $64% of that for LCO-sintered electrodes identically synthesized and processed but which were thinner and in sealed coin cells.…”

“…The thicknesses can even exceed 1000 μm, where at such thicknesses, composite electrodes can be challenging to fabricate with robust mechanical properties via conventional routes. 9,10 Increased thickness for battery electrodes is a general strategy to increase the cell level energy density because less volume and mass are dedicated to inactive current collectors and separators. 11,12 Thus, thick sintered electrodes can result in high energy density at the cell level.…”

“…First, as will be described in this manuscript, they can be fabricated very thick while still maintaining mechanical stability. The thicknesses can even exceed 1000 μm, where at such thicknesses, composite electrodes can be challenging to fabricate with robust mechanical properties via conventional routes 9,10 . Increased thickness for battery electrodes is a general strategy to increase the cell level energy density because less volume and mass are dedicated to inactive current collectors and separators 11,12 .…”

Design of Scalable, Next-Generation Thick Electrodes: Opportunities and Challenges

“…However, there remain significant barriers to their implementation: Thick electrodes possess poor power density characteristics due to ion transport limitations, 3 and they are difficult to manufacture at scale using present processes. In this issue of ACS Nano, Wu et al report a novel methodology for the manufacture of thick, high-capacity electrodes, 4 highlighting the need for further discourse on the topic. In this Perspective, we consider the implications of thick electrodes on LIB performance and assess the challenges and opportunities that lie at the heart of their design, manufacture, and scalability.…”