Graphite Powder Density
graphite powder density is important for battery manufacturers to know because it affects processing and material handling. It is particularly important for the cohesion of powders, which can cause aggregates in the final slurry and result in defective anodes.
Several methods are available to measure the true density of a bulk sample of a porous material, such as helium or mercury, to exclude voids and spaces between the particles. Depending on the application, the density may also be measured in a vacuum to remove ambient gas.
A simple method for determining the apparent density of a powder is presented in figure 2. This method relies on a thick glass cylinder with a known weight placed between two pistons which enable the pressure gradient to be induced within the sample during compression.
The apparent density is then presented against the height h of the sample in the compression chamber. As shown in figure 2, the apparent density of graphite A (graphite B is only used as an example) increases significantly as the height h is increased, due to the pressure gradient in the compressed sample.
The treatment according to the invention consists of mechanically abrading the irregularly shaped graphite particles with a suitable energy dose until their Scott density and/or tamped density have increased to a considerable extent. The effect is primarily due to the abrasion, but also includes a change in the other properties, such as the particle size.