Pore Size Independent Particle Size Control of Mesoporous N‐doped Carbon Nanospheres for 3D Bottom‐Up Electrode Design

The rational design of electrodes is crucial for improving electrochemical energy storage and conversion devices. High-performance devices require porous carbon electrodes with controlled intraparticle properties - such as morphology, size, porosity, elemental composition, and graphitic microstructure - and interparticle features like electrode-level porosity, percolation pathways, and tortuosity, that influence mass transport. Here, mesoporous N-doped carbon (MPNC) nanospheres with independently tunable particle size at a fixed pore size is reported. Extending the previously established synthesis toolbox, independent control over particle and pore sizes is demonstrated. Using a 9 nm SiO₂ hard template, particle sizes between 50 and 300 nm is adjusted while maintaining comparable physicochemical properties. These MPNC nanospheres are evaluated as supercapacitor electrodes in coin cells using 1.0 m LiPF₆ in EC/DEC as electrolyte. The highest specific capacitance - 67 F g^-1 at 0.1 A g^-1 - is obtained with the largest particles, attributed to reduced tortuosity and improved electrode percolation. As all samples exhibited similar surface areas (≈950 m² g^-1), performance differences highlight particle size-dependent diffusion limitations. This study establishes a bottom-up approach for engineering electrode architectures, enabling independent control of pore and particle sizes of MPNC nanospheres and providing a platform to systematically investigate their effects on electrochemical performance.