Graphite Electrode Crack

Degradation of the graphite electrode is one of the most important factors that can affect the performance and life of lithium-ion battery. The degradation of the electrode graphite is caused by various mechanisms including volume changes, oxidation, and mechanical damage. This article discusses the mechanical degradation caused by composite graphite electrodes, which is mostly due to intercalation and disintercalation Li-ions. There is an interplay of these two processes which leads to the formation a SEI-film and a reduction in electrical resistance. This is why it is crucial to improve the performance of graphite electrodes and create a better method to increase their cycle life.

Using DIC we can analyse the changes in the bending curve and modulus for a composite graphite commercial electrode over multiple electrochemical cycles. The bending curve of the electrode shows almost two stages during each cycle: first, the bending curve increases linearly with the insertion of Li ions; secondly, the bending curve starts to decrease with the removal of Li ions. The variation trends of the elastic modulus in both cycles are similar, and their values differ within a limited range.

You can see that from the perspective of hysteresis loops the first few cycles are larger than subsequent loops. That indicates the composite graphite electrode has suffered more initial damage. The results are consistent with the hypothesis that the lithiation causes more damage to graphite, resulting in an increase of volume and decrease of elastic modulus.

We can conclude from the results of this study that the cyclic degradation of composite graphite electrodes is a complex phenomenon. The interaction of volume changes, stress and strains with concentration is the key. According to the analysis of the graphite composite electrode's modulus curves, the variations of stress and strain, as well as the elastic modulus follow a similar pattern. The curvature increases during lithiation while the elastic modulus decreases during discharge.

The quality (joint products) of graphite electrodes is an indicator of quality in electric furnace steelmaking. The key indicators include the volume density, resistivity, strength and elastic modulus of the graphite electrode. It is very easy to break graphite electrodes if the indicators are poor. To ensure long-term usage, you should also be aware of the precision with which the joints and graphite electrodes are machined. The graphite electrodes should also be stored in an environment that is dry to prevent rusting and corrosion. Finally, it is necessary to avoid excessive use of graphite electrodes in the smelting process in order to reduce their consumption. Saving money will improve the efficiency of smelting systems.

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