Silicon as a promising candidate for the next-generation high-capacity lithium-ion battery anode is characterized by outstanding capacity, high abundance, low operational voltage, and environmental benignity. However, large volume changes during Si lithiation and de-lithiation can seriously impair its long-term cyclability. Although extensive research efforts have been made to improve the electrochemical performance of Si-based anodes, there is a lack of efficient fabrication methods that are low cost, scalable, and self-assembled. In this report, co-axial fibrous silicon asymmetric membrane has been synthesized using a scalable and straightforward phase inversion method combined with dip coating as inspired by the hollow fiber membrane technology that has been successfully commercialized over the last decades to provide billions of gallons of purified drinking water worldwide. We demonstrate that ~ 90% initial capacity of co-axial fibrous Si asymmetric membrane electrode can be maintained after 300 cycles applying a current density of 400 mA g−1. The diameter of fibers, size of silicon particles, type of polymers, and exterior coating have been identified as critical factors that can influence the electrode stability, initial capacity, and rate performance. Much enhanced electrochemical performance can be harvested from a sample that has thinner fiber diameter, smaller silicon particle, lower silicon content, and porous carbon coating. This efficient and scalable approach to prepare high-capacity silicon-based anode with outstanding cyclability is fully compatible with industrial roll-to-roll processing technology, thus bearing a great potential for its future commercialization.
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Experimental Study of NCM-Si Batteries With Bi-Directional Actuation
Silicon is regarded as one of the most promising anode materials for lithium-ion batteries. Its high theoretical capacity (4000 mAh/g) has the potential to meet the demands of high-energy density applications, such as electric air and ground vehicles. The volume expansion of Si during lithiation is over 300%, indicating its promise as a large strain electrochemical actuator. A Si-anode battery is multifunctional, storing electrical energy and actuating through volume change by lithium-ion insertion.
To utilize the property of large volume expansion, we design, fabricate, and test two types of Si anode cantilevers with bi-directional actuation: (a) bimorph actuator and (b) insulated double unimorph actuator. A transparent battery chamber is fabricated, provided with NCM cathodes, and filled with electrolyte. The relationship between state of charge and electrode deformation is measured using current integration and high-resolution photogrammetry, respectively. The electrochemical performance, including voltage versus capacity and Coulombic efficiency versus cycle number, is measured for several charge/discharge cycles. Both configurations exhibit deflections in two directions and can store energy. In case (a), the largest deflection is roughly 35% of the cantilever length. Twisting and unexpected bending deflections are observed in this case, possibly due to back-side lithiation, non-uniform coating thickness, and uneven lithium distribution. In case (b), the single silicon active coating layer can deflect 12 passive layers.
more » « less- Award ID(s):
- 1662055
- NSF-PAR ID:
- 10304209
- Date Published:
- Journal Name:
- 2021 ASME SMASIS
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Applications of silicon as a high-performance anode material has been impeded by its low intrinsic conductivity and huge volume expansion (> 300%) during lithiation. To address these problems, nano-Si particles along with conductive coatings and engineered voids are often employed, but this results in high cost anodes. Here, we report a scalable synthesis method that can realize high specific capacity (~800 mAh g-1), ultrafast charge/discharge (at 8 A g-1 Si) and high initial Coulombic efficiency (~90%) with long cycle life (1000 cycles) at the same time. To achieve 1000 cycle stability, micron-sized Si particles are subjected to high-energy ball milling to create nanostructured Si building blocks with nano-channel shaped voids encapsulated inside a nitrogen (N)-doped carbon shell (termed as Si micro-reactor). The nano-channel voids inside a Si micro-reactor not only offer the space to accommodate the volume expansion of Si, but also provide fast pathways for Li ion diffusion into the center of the nanostructured Si core and thus ultrafast charge/discharge capability. The porous N-doped carbon shell helps to improve the conductivity while allowing fast Li ion transport and confining the volume expansion within the Si micro-reactor. Submicron-sized Si micro-reactors with limited specific surface area (35 m2 g-1) afford sufficient electrode/electrolyte interfacial area for fast lithiation/delithiation, leading to the specific capacity ranging from ~800 to 420 mAh g-1 under ultrafast charging conditions (8 A g-1), but not too much interfacial area for surface side reactions and thus high initial coulombic efficiency (~90%). Since Si micro-reactors with superior electrochemical properties are synthesized via an industrially scalable and eco-friendly method, they have the potential for practical applications in the future.more » « less
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Among anode materials for lithium ion batteries, silicon (Si) in known for high theoretical capacity and low cost. Si exhibits over 300% volume change during cycling, potentially providing large displacement. In this paper, we present the design, fabrication and testing of a multifunctional NCM-Si battery that not only stores energy, but also utilizes the volume change of Si for actuation. The battery is transparent, thus allowing the visualization of the actuation process during cycling. This paper shows Si anode design that stores energy and actuates through volume change associated with lithium insertion. Experimental results from a transparent battery show that a Cu current collector single-side coated with Si nanoparticles can store 10:634mWh (charge)/ 2:074mWh (discharge) energy and bend laterally with over 40% beam length displacement. The unloaded anode is found to remain circular shape during cycling. Using a unimorph cantilever model, the Si coating layer actuation strain is estimated to be 30% at 100% SOC.more » « less
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Ever-increasing demands for energy, particularly being environmentally friendly have promoted the transition from fossil fuels to renewable energy.1Lithium-ion batteries (LIBs), arguably the most well-studied energy storage system, have dominated the energy market since their advent in the 1990s.2However, challenging issues regarding safety, supply of lithium, and high price of lithium resources limit the further advancement of LIBs for large-scale energy storage applications.3Therefore, attention is being concentrated on an alternative electrochemical energy storage device that features high safety, low cost, and long cycle life. Rechargeable aqueous zinc-ion batteries (ZIBs) is considered one of the most promising alternative energy storage systems due to the high theoretical energy and power densities where the multiple electrons (Zn2+) . In addition, aqueous ZIBs are safer due to non-flammable electrolyte (e.g., typically aqueous solution) and can be manufactured since they can be assembled in ambient air conditions.4As an essential component in aqueous Zn-based batteries, the Zn metal anode generally suffers from the growth of dendrites, which would affect battery performance in several ways. Second, the led by the loose structure of Zn dendrite may reduce the coulombic efficiency and shorten the battery lifespan.5
Several approaches were suggested to improve the electrochemical stability of ZIBs, such as implementing an interfacial buffer layer that separates the active Zn from the bulk electrolyte.6However, the and thick thickness of the conventional Zn metal foils remain a critical challenge in this field, which may diminish the energy density of the battery drastically. According to a theretical calculation, the thickness of a Zn metal anode with an areal capacity of 1 mAh cm-2is about 1.7 μm. However, existing extrusion-based fabrication technologies are not capable of downscaling the thickness Zn metal foils below 20 μm.
Herein, we demonstrate a thickness controllable coating approach to fabricate an ultrathin Zn metal anode as well as a thin dielectric oxide separator. First, a 1.7 μm Zn layer was uniformly thermally evaporated onto a Cu foil. Then, Al2O3, the separator was deposited through sputtering on the Zn layer to a thickness of 10 nm. The inert and high hardness Al2O3layer is expected to lower the polarization and restrain the growth of Zn dendrites. Atomic force microscopy was employed to evaluate the roughness of the surface of the deposited Zn and Al2O3/Zn anode structures. Long-term cycling stability was gauged under the symmetrical cells at 0.5 mA cm-2for 1 mAh cm-2. Then the fabricated Zn anode was paired with MnO2as a full cell for further electrochemical performance testing. To investigate the evolution of the interface between the Zn anode and the electrolyte, a home-developed in-situ optical observation battery cage was employed to record and compare the process of Zn deposition on the anodes of the Al2O3/Zn (demonstrated in this study) and the procured thick Zn anode. The surface morphology of the two Zn anodes after circulation was characterized and compared through scanning electron microscopy. The tunable ultrathin Zn metal anode with enhanced anode stability provides a pathway for future high-energy-density Zn-ion batteries.
Obama, B., The irreversible momentum of clean energy.
Science 2017, 355 (6321), 126-129.Goodenough, J. B.; Park, K. S., The Li-ion rechargeable battery: a perspective.
J Am Chem Soc 2013, 135 (4), 1167-76.Li, C.; Xie, X.; Liang, S.; Zhou, J., Issues and Future Perspective on Zinc Metal Anode for Rechargeable Aqueous Zinc‐ion Batteries.
Energy & Environmental Materials 2020, 3 (2), 146-159.Jia, H.; Wang, Z.; Tawiah, B.; Wang, Y.; Chan, C.-Y.; Fei, B.; Pan, F., Recent advances in zinc anodes for high-performance aqueous Zn-ion batteries.
Nano Energy 2020, 70 .Yang, J.; Yin, B.; Sun, Y.; Pan, H.; Sun, W.; Jia, B.; Zhang, S.; Ma, T., Zinc Anode for Mild Aqueous Zinc-Ion Batteries: Challenges, Strategies, and Perspectives.
Nanomicro Lett 2022, 14 (1), 42.Yang, Q.; Li, Q.; Liu, Z.; Wang, D.; Guo, Y.; Li, X.; Tang, Y.; Li, H.; Dong, B.; Zhi, C., Dendrites in Zn-Based Batteries.
Adv Mater 2020, 32 (48), e2001854.Acknowledgment
This work was partially supported by the U.S. National Science Foundation (NSF) Award No. ECCS-1931088. S.L. and H.W.S. acknowledge the support from the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 22011044) by KRISS.
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The objective of this investigation was to utilize the first-principles molecular dynamics computational approach to investigate the lithiation characteristics of empty silicon clathrates (Si 46 ) for applications as potential anode materials in lithium-ion batteries. The energy of formation, volume expansion, and theoretical capacity were computed for empty silicon clathrates as a function of Li. The theoretical results were compared against experimental data of long-term cyclic tests performed on half-cells using electrodes fabricated from Si 46 prepared using a Hofmann-type elimination–oxidation reaction. The comparison revealed that the theoretically predicted capacity (of 791.6 mAh/g) agreed with experimental data (809 mAh/g) that occurred after insertion of 48 Li atoms. The calculations showed that overlithiation beyond 66 Li atoms can cause large volume expansion with a volume strain as high as 120%, which may correlate to experimental observations of decreasing capacities from the maximum at 1030 mAh/g to 553 mA h/g during long-term cycling tests. The finding suggests that overlithiation beyond 66 Li atoms may have caused damage to the cage structure and led to lower reversible capacities.more » « less
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/SMASIS2021-67596
