3D Correlative Imaging of Lithium Ion Concentration in a Vertically Oriented Electrode Microstructure with a Density Gradient

Abstract

The performance of Li + ion batteries (LIBs) is hindered by steep Li + ion concentration gradients in the electrodes. Although thick electrodes (≥300 μm) have the potential for reducing the proportion of inactive components inside LIBs and increasing battery energy density, the Li + ion concentration gradient problem is exacerbated. Most understanding of Li + ion diffusion in the electrodes is based on computational modeling because of the low atomic number (Z) of Li. There are few experimental methods to visualize Li + ion concentration distribution of the electrode within a battery of typical configurations, for example, coin cells with stainless steel casing. Here, for the first time, an interrupted in situ correlative imaging technique is developed, combining novel, full-field X-ray Compton scattering imaging with X-ray computed tomography that allows 3D pixel-by-pixel mapping of both Li + stoichiometry and electrode microstructure of a LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathode to correlate the chemical and physical properties of the electrode inside a working coin cell battery. An electrode microstructure containing vertically oriented pore arrays and a density gradient is fabricated. It is shown how the designed electrode microstructure improves Li + ion diffusivity, homogenizes Li + ion concentration through the ultra-thick electrode (1 mm), and improves utilization of electrode active materials.

Realising higher capacity and stability for disordered rocksalt oxyfluoride cathode materials for Li ion batteries

“… 2 Two prevalent cathode materials, LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) 3 and LiNi x Mn y Co z O 2 (NMC), 4 adopt a layered crystal structure that has an ordered arrangement of Li and transition metal (TM) atoms where Li + ions diffuse in the alkali layer with a 2D pathway upon battery (dis)charge. 5 Another widely used cathode material LiFePO 4 (LFP) has an olivine crystal structure that still exhibits a clear 1D Li + diffusion pathway. 6 For decades, cation disordering, i.e., mixing of the Li and transition metals (TMs) atoms in the lattice sites, has been considered to limit Li + ion diffusion.…”

Diagnosis of Current Flow Patterns Inside Fault‐Simulated Li‐Ion Batteries via Non‐Invasive, In Operando Magnetic Field Imaging

“…Postmortem and in situ/operando analytical techniques using advanced imaging tools have been developed to unveil failure mechanisms at the material level of batteries, identifying physicochemical defects of active materials, [9][10][11][12][13] electrolyte degradation, [14][15][16] and structural damage in inactive components (e.g., separators, current collectors, tabs). [17][18][19][20] However, correlating material-level defects with cell-level failure scenarios is challenging because these defects randomly occur within complex cell structures.…”