STRUCTURAL ENGINEERING OF SAFE LITHIUM-ION BATTERIES
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Date
2023
Authors
Nwaogu, Emmanuel Chisom
Journal Title
Journal ISSN
Volume Title
Publisher
School of Engineering and Digital Sciences
Abstract
To consider lithium-metal batteries a good choice for next-generation energy storage system, it is important to maintain a long-term cyclability and reduce the excess lithium metal deposits. The application of Li-metal batteries has been limited due to problem of dendrite formation caused by Li metal, including low Coulombic efficiency and short circuits. This study has focused on creating a three-dimensional (3D) copper current collector chosen to serve as anode materials by modifying it with 50 nm thickness of gold to promote deposition of Li metal without the formation of dendrites. The 3D-Cu current collector maintained lithiophilic properties after modification, which not only lowered the local current density but also provided a large surface area for Li deposition. After half-cell construction of Au-2D-Cu and Au-3D-Cu with Li-metal 0 mV overpotential was achieved after plating and stripping for above 24 hours. Furthermore, the Au-3D-Cu current collector showed superior properties when compared to 2D-Cu, 3D-Cu, and Au-2D-Cu in terms of longer stable cyclability and CE.
NCM cathode and 2D-Cu, 3D-Cu, Au-2D-Cu, and Au-3D-Cu current collectors were constructed separately as full cells, Au-3D||NCM full cell showed a high capacity of about 181 mAh g-1 at the first cycle and later decreased to 100 mAh g-1 after 100 cycles which is superior compared to the Au-2D||NMC, 2D||NCM, and 3D||NCM, which had 170 mAh g-1, 164 mAh g-1, and 160 mAh g-1 at first reversible capacity, and steadily decreased to 80, 20, and 15 after 100 cycles, respectively. Additionally, the use of high concentration tri-lithium salt electrolyte of 1.5M LiTFSI + 1M LiDFOB, + 0.05M LiPF6 in FEC/DDME (2:3 v/v) at 0.2 C contributed to achieving high capacity, capacity loss reduced, stable reversibility over a prolonged cycling, and high CE of 99.9% especially in the case of Au@3D||NCM also, the post mortem analysis with SEM confirmed the dendrite growth suppression in Au@3D||NCM after 100 cycles.
However, complex battery construction and capacity loss was the two major challenges the research faced due to limited supply of lithium. Fortunately, we were able to mitigate this problems by utilizing a high concentration tri-lithium salt electrolyte and modification of the current collector. For better result, I will recommend that more experiments should be conducted, varying different thickness of the sputtered gold ranging from 40 nm, 30 nm, and 25 nm. This approach may lead to more better and viable result in the future.
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Keywords
Type of access: Embargo, Lithium-ion Batteries
Citation
Nwaogu, E. Ch. (2023). Structural engineering of safe lithium-ion batteries. School of Engineering and Digital Sciences