Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage

Significance 

Development of efficient lithium-ion batteries is highly promising power source for future generation energy applications. This can be attributed to their efficiency and portability. Currently, graphite has been mainly used as anode materials in lithium-ion batteries. Unfortunately, graphite-based anodes have low lithium storage capacity which compromises the performance of lithium-ion batteries. As such, researchers have been looking for alternatives and have identified amorphous anode material as a promising solution.

Presently, enhancing the performances of anodic materials have been a major focus. Other than interfacial engineering, other methods have also been developed to increase lithium storage capacities. However, discrete distribution on the anode material surface during particles deposition has resulted in unstable lithiation and delithiation processes. Therefore, effective methods for achieving the uniform metal layer on the anode materials is highly desirable. In a recently published literature, ternary metal oxides with different metal cations exhibited excellent structural stability, reversible capacity, and theoretical capacity thus promising anodic materials for lithium-ion batteries. However, their low electron diffusion rate leading to unstable lithiation and delithiation which have not been fully explored.

To this note, scientists led by Professor Jinhu Yang at Tongji University designed and constructed amorphous porous CoSnO3 nanocubes for high-performance anodic material. The design was based on the Au atomic cluster layer-terminated heterointerface that was constructed using the galvanic replacement reaction method. They further investigated the advantages of using the CoSnO3/ Au composites in terms of structural composition, electrical conductivity, reversibility, and lithium diffusion rate. Their research work is currently published in the research journal, ACS Nano.

In brief, the research team initiated their studies by exploring interfacial engineering as a method for optimizing the electrode materials properties suitable for energy applications. Additionally, for the lithium-ion batteries investigated here, a galvanic replacement method was used to fabricate the amorphous porous CoSnO3 nanocubes. Eventually, they used density functional theory calculations to investigate the lithium storage mechanism at the CoSnO3//Au heterointerface.

The authors observed that the fabricated amorphous anode material exhibited high reversible capacity, good rate capability as well as good cycling stability. In addition, the performance of the lithium-ion batteries was significantly enhanced. The high lithium ion batteries performance was attributed to the amorphous nature of the CoSnO3 //Au heterointerface. Furthermore, it was worth noting that the amorphous nature was also the reason for the improved ion diffusion, electron transport as well as minimizing the volume strain.

In summary, Ting He (PhD candidate) and her colleagues successfully constructed CoSnO3 //Au heterointerface for fast and high capacity lithium storage. To actualize their study, it was necessary to perform density functional theory calculations. An enhanced theoretical lithium storage capacity was obtained due to the initiated atomic polarization and reduced lithium ion diffusion barriers. Altogether, the study pioneers the use of amorphous materials to realize high-performance lithium-ion batteries which will be of great significance for future energy advancement.

Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage - Advances in Engineering
Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage - Advances in Engineering

Figure 1. (a) Schematic illustration for the fabrication of the amorphous porous CoSnO3/Au composite nanocubes. (b-g) SEM and TEM images of the (b, c) CoSn(OH)6 solid cubes, (d, e) porous CoSn(OH)6/Au nanocubes and (f, g) amorphous porous CoSnO3/Au nanocubes.

Figure 2. (a, b) HRTEM images, (c) the SAED pattern and (d) STEM image with the corresponding elemental mappings of Co, Sn, O, and Au of the amorphous CoSnO3/Au nanocubes. (e) XRD patterns of the CoSn(OH)6/Au nanocubes and amorphous CoSnO3/Au nanocubes. (f) XPS spectra of the CoSnO3/Au nanocubes. Inset in (a) is a low-magnification TEM image of a CoSnO3/Au nanocube which was selected for HRTEM observation. Inset in (f) is the high-resolution XPS spectrum for Au 4f.
Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage - Advances in Engineering
Figure 3. (a) CV curves of the CoSnO3/Au nanocube electrode for the first three cycles at a scan rate of 0.2 mV s-1. (b) Voltage profiles of the CoSnO3/Au electrode at 0.1 A g-1. (c) Rate performance of the CoSnO3/Au and CoSnO3 electrodes. (d, e) Cycling performance of the CoSnO3/Au and CoSnO3 electrodes at (d) 0.2 A g-1 and (e) 5 A g-1.
Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage - Advances in Engineering
Figure 4. HRTEM images of the (a) CoSnO3 and (b) CoSnO3/Au nanocubes after the initial 3 cycles. (c) EIS of the CoSnO3 and CoSnO3/Au electrodes before cycling under a frequency range from 100 kHz to 100 mHz.
Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage - Advances in Engineering
Figure 5. (a) Planar-averaged electrostatic potential for the amorphous CoSnO3/Au composite. (b) Planar-averaged electron density difference and the charge density difference for the amorphous CoSnO3/Au composite, in which yellow and cyan areas indicate electron accumulation and depletion, respectively. (c) The side views of lithium diffusion pathways at the heterointerface of the CoSnO3/Au composite and on the surface of the CoSnO3. (d) Diffusion energy profile for lithium diffusion at heterointerface of the CoSnO3/Au composite and over the surface of the CoSnO3. Inset of (d) is the top views of the diffusion pathways given in (c).
Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage - Advances in Engineering
Figure 6. Schematic illustration shows the theoretical capacity (TC) of reversible lithiation/delithiation reactions over the CoSnO3 and CoSnO3/Au electrodes.

About the author

Prof. Jinhu Yang received his Ph.D. degree from Peking University, Beijing, China, in 2005. He worked at The Hong Kong University of Science and Technology (Hong Kong) as a Research Associate from 2005 to 2006, the University of Tokyo as a Foreign Researcher supported by JSPS organization from 2006 to 2008, and Munich University as a Humboldt Research Fellow from 2009 to 2011, respectively. He is currently a professor at Tongji University, Shanghai, China. His current research focuses on the design and fabrication of nanostructure-based energy devices including rechargeable batteries, supercapacitors and electrocatalysis.

About the author

Ting He is currently a Ph.D. candidate at Tongji University (China) under the supervision of Prof. Jinhu Yang. She received the B.S. degree (2014) from Shanghai Normal University (China). Ting’s research interests are focused on composition and architecture design towards energy conversion and storage, including photoelectrocatalysis, lithium/sodium-ion batteries and supercapacitors. She has been awarded the Bayer scholarship (2016) and shanghai society of chemistry and chemical industry scholarship (2017). Her work has been published in high-profile journals such as Advanced Energy Materials and ACS Nano.

Reference

He, T., Feng, J., Ru, J., Feng, Y., Lian, R., & Yang, J. (2019). Constructing Heterointerface of Metal Atomic Layer and Amorphous Anode Material for High-Capacity and Fast Lithium Storage. ACS Nano13(1), 830-838.

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