| Author: | Cai, Jiehua |
| Title: | Development of advanced thin lithium metal anodes for high-performance lithium metal batteries |
| Advisors: | Zheng, Zijian (SFT) |
| Degree: | Ph.D. |
| Year: | 2025 |
| Department: | School of Fashion and Textiles |
| Pages: | xix, 138 pages : color illustrations |
| Language: | English |
| Abstract: | Nowadays, the ever-increasing demand for next-generation portable and flexible electronics has stimulated great efforts to explore high-energy storage devices. Considering that the energy densities of lithium-ion batteries (LIBs) have almost reached their theoretical limit, it urges the development of advanced battery technologies that go beyond LIBs. Since lithium (Li) metal has the highest theoretical capacity and the lowest electrochemical potential, Li metal batteries (LMBs) have emerged as the most promising candidate. However, the commercialization of LMBs is hindered by the uncontrollable Li dendritic growth on the anode. Despite the significant strategies proposed, the practicality of LMBs is still far from satisfactory because the Li metal involved is excessively thick. To enhance energy density, it is essential to employ a thin (thickness, ≤ 50 μm) Li metal anode (LMA) in battery configurations, which can reduce the excess weight and volume within the battery. However, challenges remain in balancing the electrochemical stability, mechanical flexibility, and energy density of thin LMA-based batteries. To address these challenges, we try to develop advanced thin LMAs through material selection, lithophilic modification, and structural design. Three types of thin LMAs, which were developed based on different substrates, aiming to achieve high-performance LMBs, are demonstrated. Firstly, a conductive textile framework with Janus wettability to Li was developed by depositing lithophilic antimony (Sb) material on the Ni coated carbon cloth. As such, a thin yet ultrastable Janus Li-textile anode was rapidly fabricated through selective wetting, which yielded a thin Li (~50 μm) coating only on the lithophilic side of the textile framework. This Janus Li-textile anode demonstrated well-strengthened stability and record-lengthened lifespan by suppressing the formation of dendrite through the guided-deposition behavior and top-buffering space. Even at a high depth of discharge (DOD) of 75%, the Janus Li-textile anode presented an ultralong lifespan of over 3000 hr. The LMBs using the Janus Li-textile anode exhibited an improved energy density by 30%, and achieved an outstanding working life of 2000 cycles with capacity retention of 99.94% per cycle. The as-assembled pouch cell showed excellent cycling stability and impressive flexibility with high bending tolerance. Furthermore, to achieve high flexibility without sacrificing the energy density of the battery, a thin, ultralight, and flexible composite LMA was developed by sandwiching a thin Li foil in between two ultralight fabric layers through mechanical rolling. The sandwiched Li (SW Li) anode showed a lightweight nature, which was only 37.4% of the weight of foil-based thin LMAs. The SW Li anode was compatible with different high-loading commercial cathodes, showing improved electrochemical stability due to the fabric framework and interfacial alloy layer. Meanwhile, the mechanical support provided by the fabric layers endowed the SW Li with exceptional flexibility, allowing it to be folded into an origami shape and bent 10000 times at a radius of 1.5 mm. LMBs adopting SW Li not only delivered high energy of 309 Wh kg⁻¹, but also presented outstanding flexibility with a remarkably high figure of merit for flexible battery (163.8), outperforming the state-of-the-art flexible batteries. Finally, a facile approach was developed to achieve high-performance anode-free LMBs through thermally evaporating an ultrathin (50 nm) layer of Sb on the surface of Cu foil (CuSb). The simple surface modification effectively improved Li deposition behavior, thus enhancing cyclic stability and prolonging the lifespan of the anode-free batteries. Specifically, the modified Cu foil showed a prolonged cycling life of 400 cycles with an impressive average Coulombic efficiency (CE) of ~99.3%. The anode-free NCM811||CuSb batteries also demonstrated a remarkable energy density of 425 Wh kg⁻¹, and improved cycling stability at a practical high areal capacity of over 4 mAh cm⁻². In conclusion, we proposed feasible strategies to develop electrochemically stable, mechanically flexible, and high-energy thin LMAs through facile processing techniques. Such thin LMAs have demonstrated their potential in advancing the performance of batteries, contributing to achieving long-term stability, long-life cycle, high energy density as well as outstanding flexibility. Therefore, this study provided promising and effective avenues for the development of advanced thin LMAs, paving the way for the realization of next-generation LMBs. |
| Rights: | All rights reserved |
| Access: | open access |
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