In lithium-ion batteries, energy and power densities depend heavily on the electrode microstructure. Because their structure is determined during the manufacturing process, manufacturing steps must be understood in great detail to tailor the electrodes to the specific needs of the application. The present work investigates the influence of wet mixing time on the conductive networks and consequently on electrode performance. FIB-SEM tomography coupled with 3D-resolved simulations unveils an increased homogeneity of the carbonaceous network inside a NMC622 electrode for longer dispersion times. Quantitative structural analysis is used to correlate microstructure and electrochemical performance using rate capability tests and electrochemical impedance spectroscopy. Longer mixing increases both active material particle coverage in the carbon binder domain (CBD) and homogeneity of the CBD, leading to higher electronic conductivity and reduced contact resistance. Conversely, the more homogeneous CBD negatively affects ionic transport inside the electrolyte due to pore blockage and lowers available surface area of the active material. This leads to a 21% increase in solid diffusion length and a reduction in surface area of 21% after doubling the wet mixing time from 30 to 60 min. Overall, this contribution untangles the complex interaction between wet mixing duration, microstructural evolution, and electrode performance.
The Mn-based spinel-type cathode material LiMn2O4 (LMO) attracts widespread attention due to its low cost, eco-friendly characteristics, ease of synthesis, and stable chemical properties. However, its intrinsic two-phase reaction leads to relatively lower practical capacity and poor cycling stability, restricting its application. This study introduces partial disorder into LMO through high-energy ball milling, synthesizing the fluorinated and lithium-rich material Li1.5Mn1.73O3.8F0.2 (LMOF). Structural characterization, including X-ray diffraction, neutron diffraction, transmission electron microscopy, and X-ray absorption spectroscopy, reveals cation disorder compared with ordered LMO. The voltage profiles indicate a solid-solution reaction in partially disordered LMOF, replacing the conventional sluggish two-phase transition in fully ordered LMO. The suppressed phase transitions contribute to improved cycling stability and rate capability. Apparent lithium-ion diffusivity is enhanced by approximately two to three orders of magnitude, with the difference also reflecting particle-size-related surface-area effects, while impedance is reduced. Electrochemical evaluation shows a high initial capacity of 337.53 mAh g-1 and capacity retention of 86.54% after 100 cycles. This work shows that tuning cation disorder offers a promising strategy to optimize spinel-type cathodes for sustainable, high-performance lithium-ion batteries.
The performance of sodium-ion batteries (SIBs) is critically influenced by separator design, which affects separator–electrolyte interactions, ion transport, cycling stability and cell-level energy density. This study systematically evaluates the impact of polyolefin-based, cellulose-based, and ceramic-coated separators in O3-NaNi1/3Mn1/3Fe1/3O2//hard carbon full cells. In parallel, a theoretical 15 Ah cell is used to assess how separator thickness, density, porosity, and electrolyte inventory contribute to gravimetric and volumetric energy density under a fixed-capacity assumption. The model indicates that gravimetric energy density varies by ∼3%, whereas volumetric energy density varies by ∼6% across the tested separators, primarily due to separator thickness and porosity-dependent electrolyte requirements. Experimentally, the separators with enhanced wettability, particularly boehmite-coated polyethylene monolayer (SP3) and cellulose-based separator (SP5), deliver superior capacity retention (∼90%). In contrast, conventional polyolefin/trilayer separators with limited wettability or high internal resistance show diminished performance. A qualitative Pearson trend analysis suggests that lower contact angles, corresponding to higher wettability, may be associated with improved performance. Overall, these findings underscore the importance of optimizing separator properties (i.e. thickness, porosity, and surface morphology/chemistry) to enhance the performance, efficiency, and scalability of next-generation SIBs.
