button cell battery cr1620.Analysis of graphene material application technology in lithium battery anode

　　Analysis of graphene material application technology in lithium battery anode

　　A full battery made of a graphene ball-coated positive electrode and a graphene ball negative electrode has a high volumetric energy density of 800Wh L-1 under commercial battery conditions, and has a capacity retention rate of 78.6% after 500 cycles at 60°C. .

　　【introduction】

　　Lithium batteries are widely used in today's human social life, such as electric vehicles and portable electronic devices. However, these commercial lithium batteries have low energy density and cannot fully meet the needs of daily use. Moreover, the capacity of most batteries will decrease during rapid charging and discharging, and their rate characteristics are poor.

　　In addition, in addition to energy density and fast charging, long cycle life performance at high temperatures (around 60 degrees Celsius) is also very important. So far, the nickel-rich and lithium-rich layered oxide materials that are considered to be able to replace LiCoO2 have basically negligible losses in energy density and cycle life during fast charging. Therefore, it is very important to find an advanced anode material for fast charging, because today's graphite anodes will deposit metallic lithium to produce lithium dendrites when charged at high rates.

　　【Achievements Introduction】

　　Recently, Dr. InHyukSon's team from Samsung Advanced Technology Research Institute in South Korea, Professor Jang Wook Choi's team from Seoul National University in South Korea (co-corresponding author), together with Korea Electric Research Institute and SDI R&D Center, published an article titled "Grapheneballs for lithium rechargeable batteries with fast charging and high volumetric energy densities" in the famous journal Nature Communications. This article reports a graphene-SiOx assembled graphene sphere as a coating material for high-capacity nickel-rich layered cathode materials and lithium battery anode materials. Each graphene ball is composed of a SiOx nanoparticle in the center and a graphene layer in the outer layer, similar to a 3D popcorn-like structure. SiOx nanoparticles have multiple functions. For example, they prevent the formation of SiC layers at the SiOx-graphene interface during graphene growth, ensure that graphene balls can be evenly coated on the cathode material, and ensure high specific capacity when used as anode materials. . The uniform coating of graphene balls on the nickel-rich cathode material enhances the stability of the interface between the electrolyte and the electrode, and improves the cathode's fast charging performance and cycle stability. A full battery made of a graphene ball-coated positive electrode and a graphene ball negative electrode has a high volumetric energy density of 800WhL-1 under commercial battery conditions, and has a capacity retention rate of 78.6% after 500 cycles at 60°C.

　　[Picture and text introduction]

　　Figure 1: SiO2 nanoparticles growing graphene.

　　a) TEM before CVD growth;

　　CVD growth b) after 5 min c) TEM after 30 min;

　　d)-f): The corresponding enlarged pictures in the figures a)-c);

　　g) Magnified view of graphene grown for 30 minutes and atomic energy levels;

　　h) Schematic diagram of the growth of popcorn-like graphene.

　　Figure 2: Analysis of graphene spheres during growth.

　　Characterization methods used to detect graphene growth during CVD growth:

　　a)XRD;b)XPS;

　　c) Si2p peak in XPS; EDX pattern of C, O, Si after growing graphene on SiO2 d)-e) 5min and f)-g) 30min.

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