How can nanoscale lithium diffusion proceed counter to concentration gradients?
Hummingbird Scientific has collaborated with Danwon Lee, Chihyun Nam, Jongwoo Lim, and their colleagues at Seoul National University, Pohang University of Science and Technology, Samsung Electronics, and Berkeley Lab to publish recent work tracking lithium diffusion in single crystalline LiNi1/3Mn1/3Co1/3O2 (scNMC) particles during cycling with the Hummingbird Scientific Generation V X-ray bulk liquid-electrochemical sample holder. Operando scanning transmission X-ray microscopy (STXM) was combined with post-cycling Bragg coherent diffraction X-ray imaging to uncover strain-associated lithium transport dynamics.
a) SEM image of scNMC. b) Absorption spectra (Ni L3-edge) of as-synthesized scNMC (Ni2+) and fully charged scNMC (Ni3.7+) samples. c) Schematics of an operando microfluidic cell. The scNMC/Pt working electrode is positioned on the SiNx X-ray window, while the Li metal counter/reference electrode is located outside the microdevice. Inset shows an overall cross-sectional view of the cell. d) Electrochemistry curves at 0.1 C (0.207 mA/cm2), and 3 C (6.216 mA/cm2) during operando STXM. e) Schematic comparing molecular diffusion in gas and liquid to ion diffusion in a crystalline solid. f) Evolution of Li composition for particles #S4 and #S5 during (de)lithiation at a rate of 3 0.1C (0.58 nA), and 3C (1.74 nA). Copyright © 2025 Springer Nature Limited
Contrary to the expected thermodynamically-driven transport of lithium along concentration gradients, near-uniform yet fluctuating regions of lithium-dense and lithium-poor areas were observed during cycling. An increased presence of lithium-poor regions are observed near the particle surfaces, suggesting that control of lithium surface distribution can improve rate performance in batteries, solid-state fuel cells, and memresistors. The sample holder enabled high-resolution operando spectromicroscopy of battery materials as they were cycled, with a bulk off-chip reference and counter electrode for reliable bulk-scale electrochemical measurements.
Reference: Danwon Lee, Chihyun Nam, Juwon Kim, Sooseong Hwang, Bonho Koo, Hyejeong Hyun, Jinkyu Chung, Sungjae Seo, Munsoo Song, Jaejung Song, Myeongjun Kim, Daan Hein Alsem, Norman J. Salmon, Suyong Lee, Yeonchoo Cho, Namdong Kim, David A. Shapiro & Jongwoo Lim Nature Communications 16 9018 (2025) DOI: 10.1038/s41467-025-64068-9
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