Despite numerous research on new active materials for anodes, graphite remains the most commonly used material in Li-ion batteries. The spherical shape of the graphite particles has proven to be beneficial for application in electric vehicles, especially for fast charging. So far, the spheroidization of natural flake graphite is conducted by a rigid and inefficient cascade process. In this work, a scalable classifier system was used for spheroidization, and it was demonstrated that a spheroidization time of 15 min is sufficient to improve material properties and enhance electrochemical performance while maintaining high process yields of 55%. Insights into the influence of the morphology on the intrinsic and structural properties of the graphite particles and manufactured electrodes are provided. Spheroidization creates a more efficient pore network in the coating layer while reducing the internal resistance and increasing the surface area of the particles by a factor of 1.8. We demonstrate that the spherical shape improves the discharge rate capability by 1.8, and the specific charge capacity could be enhanced by more than 237% at a C-rate of 3. An additional carbon coating could significantly decrease the specific surface area and increase the specific capacity at high C-rates.

Lithium‐ion battery cells with high‐energy density and good fast charging properties are subject of current research. One approach to achieve high‐energy densities is the use of higher mass loadings. The challenges of these so called “thick” electrodes are transport limitations: lithium ions cannot reach all layers of the electrode, which results in a drop of performance. Possible concepts to overcome these limitations are the use of different active materials (silicon oxide, graphite, and hard carbon (HC)), and a two‐layer coating of the anode to create a defined pore network, which reduces the ionic resistance and ensure better fast charging capability even at higher mass loadings (8 mAh cm⁻²). It could be demonstrated that by using a two‐layered anode with HC in the upper layer, the electrical conductivity could be increased by a factor of 10 compared to the reference anode. Furthermore, the interporous HC leads to a capacity retention increase up to 20% with no loss of capacity at moderate C‐rates and a low electrode density. This can be explained by the low tortuosity that results in additional conductive paths for the ions through the coating, reduces the ionic resistance, and ultimately enables faster lithiation of the anode.

Silicon (Si) is considered a promising anode active material to enhance energy density of lithium-ion batteries. Many studies have focused on new structures and the electrochemical performance, but only a few investigated the particulate properties in detail. Therefore, a comprehensive study on the impact of Si content (5, 10, 15 wt.%) and particle size (120, 160, 250 nm) of core–shell structured Si@Gr composites on particulate and electrode properties was conducted. It was shown that both parameters had significant impact on the specific surface area (SSA) of particles, which was later correlated to the initial capacities and coulombic efficiencies (ICEs). Furthermore, changes in pore size distribution and electrical conductivity were found. The built full cells showed high initial capacities (>150 mAh g⁻¹), good rate capability (75% at 1 C, 50% at 2 C) and ICEs (>80%). The energy density was found to increase by 32% at 15 wt.% Si compared to graphite (Gr), indicating the future potential of Si. In addition, the impact of a carbon coating was investigated (Si@Gr/C), which led to a reduction in SSA, improved particle stability and higher capacity retention. Consequently, this study emphasizes the importance of also investigating the particulate properties of Si anodes.

Current research focuses on lithium-ion battery cells with a high energy density and efficient fast-charging capabilities. However, transport limitations, and, therefore, the uniform diffusion of lithium-ions across the electrode layers, remain a challenge and could lead to reduced cell performance. One approach to overcome these transport challenges is the use of subsequently produced two-layer anodes with the particle size variation of spherical graphite (x₅₀ = 18 µm; x₅₀ = 11 µm). Thereby, a defined pore network is created, which reduces the ionic resistance and ensuring improved fast charging capabilities. The analysis focuses on the evaluation of electrode properties and the electrochemical performance. By examining the pore size distribution of the anodes, it has been found that during the manufacturing of the two-layer anodes, carbon black and binder particles are transported into the existing microstructure of the lower layer, resulting in localized densification between the anode layers. This could also be supported by color measurements. This effect also extends to electrochemical investigations, with electrochemical impedance spectroscopy showing significantly lower ionic resistances in all two-layer anodes. Reduced ionic resistance and tortuosity near the separator due to absorption effects enhance the ion diffusion and have a direct impact on anode performance. Cell ageing analysis showed a significant capacity decrease of almost 15 mAh g ⁻¹ in the single-layer references only, in contrast to the stability of the two-layer anodes. This could also be attributed to the reduced ionic resistance and active counteraction of binder migration. In conclusion, this study highlights how subsequently produced two-layer anodes significantly shape the electrode properties and cell performance of lithium-ion batteries.

Lithium‐ion batteries ensuring high energy densities are the focus of ongoing research. The main challenge is the fast charging capability, which is restricted by transport limitations of the lithium‐ions. For this reason, graphite (Gr) and hard carbon (HC) blend anodes at different calendering degrees and, thus, electrode densities are investigated in terms of their structural features as well as their electrochemical performance. The motivation of blend anodes is the combination of the advantageous properties of these materials. Due to the different microstructures of Gr and HC, major differences in the lithiation process can be found. While the turbostratic structure of HC enables fast charging, its large specific surface area is associated with a low initial Coulombic efficiency and, thus, a loss of capacity. Consequently, the combination with Gr in blends is reasonable. While the lithium‐ion diffusion is enhanced using HC, the availability of the interporous structure of HC is highly dependent on the electrode density. In addition to an increase in adhesion strength and reduction in electrical resistance, a reduction in tortuosity and lithium plating can be demonstrated. Furthermore, a higher capacity retention in the charge rate test (up to 3C) at low coating densities was found for the blends.