Thickening electrodes is one effective approach to increase active material content for higher energy and low‐cost lithium‐ion batteries, but limits in charge transport and huge mechanical stress generation result in poor performance and eventual cell failure. This paper reports a new electrode fabrication process, referred to as µ‐casting, enabling ultrathick electrodes that address the trade‐off between specific capacity and areal/volumetric capacity. The proposed µ‐casting is based on a patterned blade, enabling facile fabrication of 3D electrode structures. The study reveals the governing properties of µ‐casted ultrathick electrodes and how this simultaneously improves battery energy/power performance. The process facilitates a short diffusion path structure that minimizes intercalation‐induced stress, improving energy density and cell stability. This work also investigates the issues with structural integrity, porosity, and paste rheology, and also analyzes mechanical properties due to external force. The µ‐casting enables an ultrathick electrode (≈280 µm) that more effectively utilizes NMC‐811 (LiNi0.8Mn0.1Co0.1O2) cathode and mesocarbon microbeads anode active materials compared to conventional thick electrodes, allowing high‐mass loading (35.7 mg cm−2), 40% higher specific capacity, and 30% higher areal capacity after 200 cycles, high C‐rate performance, and longer cycle life.
Lithium-ion batteries have become a widespread energy storage technology, and research continues towards improving battery properties. One route to increase electrode areal active material loading and decrease relative volume fractions of inactive components is to increase electrode thickness, but increasing thickness can impact mechanical stability for conventional composite electrodes. All active material (AAM) electrodes, including those in this work, can mitigate mechanical and transport limitations for very thick lithium-ion electrodes. Such electrodes are free of polymer binders and conductive additives, and processed by pressing electroactive material powder into a porous pellet followed by mild sintering to improve mechanical properties. This study investigated the processing of a more recent material processed into AAM electrodes, TiNb2O7, which has relatively high volumetric capacity among reported materials processed into AAM electrodes. The anode material was characterized in AAM electrodes where different processing temperatures were used, resulting in different titanium and niobium containing phases being present. This manuscript provides insights and electrochemical consequences for fabricating AAM electrodes with multicomponent oxide phases.
more » « less- NSF-PAR ID:
- 10392868
- Publisher / Repository:
- The Electrochemical Society
- Date Published:
- Journal Name:
- Journal of The Electrochemical Society
- Volume:
- 170
- Issue:
- 1
- ISSN:
- 0013-4651
- Format(s):
- Medium: X Size: Article No. 010529
- Size(s):
- ["Article No. 010529"]
- Sponsoring Org:
- National Science Foundation
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Increasing electrode thickness is one route to improve the energy density of lithium-ion battery cells. However, restricted Li+ transport in the electrolyte phase through the porous microstructure of thick electrodes limits the ability to achieve high current densities and rates of charge/discharge with these high energy cells. In this work, processing routes to mitigate transport restrictions were pursued. The electrodes used were comprised of only active material sintered together into a porous pellet. For one of the electrodes, comparisons were done between using ice-templating to provide directional porosity and using sacrificial particles during processing to match the geometric density without pore alignment. The ice-templated electrodes retained much greater discharge capacity at higher rates of cycling, which was attributed to improved transport properties provided by the processing. The electrodes were further characterized using an electrochemical model of the cells evaluated and neutron imaging of a cell containing the ice-templated pellet. The results indicate that significant improvements can be made to electrochemical cell properties via templating the electrode microstructure for situations where the rate limiting step includes ion transport limitations in the cell.more » « less
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