Graphite Anode For Lithium Ion Battery

graphite anode for lithium ion battery

Graphite is one of the most important components of Li-ion batteries (LIBs). It is used as an active negative electrode in LIBs because it meets the voltage requirements of most cathodes and is relatively affordable, light, porous and durable.

The anode materials of Li-ion batteries undergo a lot of electrochemical reactions and mechanical degradation during battery operation. Consequently, a lot of diffusion induced stresses (DISs) develop and can eventually lead to the anode material failure.

In this paper, a model is developed to analyze the evolution of DISs under galvanostatic charge/discharge cycling. In addition, the morphology and surface of anode materials from fresh and degraded batteries were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results: The XRD measurements showed that the crystalline structure of the graphite particles changes in the anode after 500 cycles of cycling. Moreover, the SEM and TEM images of the anode showed that the spherical contact distances between the pore phase and the graphite phase as well as geometric tortuosity were greatly reduced for the degraded anode material compared with the pristine material.

These results imply that the DISs in the anode material can be explained by large volume changes of the anode materials during Li-ion insertion and extraction within the anode active particles. Hence, the formation and accumulation of DISs can be a main cause of mechanical degradation of the anode material in the LIB.

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