Micro-scale graded electrodes for improved dynamic and cycling performance of Li-ion batteries

Safety Issues in Lithium Ion Batteries: Materials and Cell Design

“…Delicate pore structures in the electrode can be obtained both in the process of coating and calendaring (Bae et al, 2013;Wang et al, 2014;Liu et al, 2018d;Cheng et al, 2019), or by physical/chemical etch after the electrode was prepared (Pröll et al, 2014;Mangang et al, 2016;Park et al, 2019). Multi-scale pore structures (Liu et al, 2017b(Liu et al, , 2018dCheng et al, 2019) in the electrode is expected to enlarge the passageway of Li-ion diffusion and reducing the internal resistance. Employing iterative co-extrusion and sintering technique, Chiang's group fabricated electrodes with dual-scale pore structure and maximized the battery power density (Bae et al, 2013).…”

“…Employing iterative co-extrusion and sintering technique, Chiang's group fabricated electrodes with dual-scale pore structure and maximized the battery power density (Bae et al, 2013). Cheng's group prepared electrode with gradient pore structure through the whole thickness direction by a layer-by-layer spray printing method, compared with electrode with mean pore size distribution, both C-rate and capacity degradation performance of the graded electrodes are significantly improved for the better Li + transport property (Cheng et al, 2019).…”

Combining composition graded positive and negative electrodes for higher performance Li-ion batteries

“…This situation was similar for both cathode and anode [25], and is a generic issue not related to any particular material. Similarly, through the electrode thickness, X-ray photoelectron spectra (XPS) surface analysis of cycled electrodes has shown that surface side-reactions leading to solid electrolyte interphase (SEI) formation were more extensive at the outer electrode surface near the separator compared with close to the current collector, which arose from inhomogeneous overpotential and reaction rates through the electrode thickness [26][27][28].…”

“…We expect that changing the local conductive carbon fraction may change the local electronic conductivity (and resistance), and thus may have a direct, homogenizing effect on the local overpotential and active material utilization. Some simulation-based studies have suggested this may be a promising line of enquiry [31], and building on recent developments in manufacturing capability for graded electrodes [28], we now investigate the effect of micro-scale composition grading in detail and in full cells. We design, manufacture and assess the performance of carefully controlled heterogeneous, graded electrode structures with the aim of promoting greater uniformity in overpotential distribution, and reaction rates across the electrode thickness.…”

Generalised single particle models for high-rate operation of graded lithium-ion electrodes: Systematic derivation and validation

“…Whilst it is difficult to overstate the success and utility of the PET approach, it can be criticised for being relatively expensive to solve. This is a particularly significant difficulty when it is being used as a tool to optimise cell design [5], or extended to model to 2-or 3-macroscopic dimensions [39,8], or as a tool in parameter estimation studies [2,33]. Its multiscale nature means that the underlying equations are posed over two separate spatial dimensions and, since these equations are nonlinear, obtaining solutions is a task that needs to be tackled numerically.…”