Persistent State-of-Charge Heterogeneity in Relaxed, Partially Charged Li1- x Ni1/3 Co1/3 Mn1/3 O2 Secondary Particles

William E Gent; Yiyang Li; Sungjin Ahn; Jongwoo Lim; Yijin Liu; Anna M Wise; Chirranjeevi Balaji Gopal; David N Mueller; Ryan Davis; Johanna Nelson Weker; Jin-Hwan Park; Seok-Kwang Doo; William C Chueh

doi:10.1002/adma.201601273

Persistent State-of-Charge Heterogeneity in Relaxed, Partially Charged Li1- x Ni1/3 Co1/3 Mn1/3 O2 Secondary Particles

Adv Mater. 2016 Aug;28(31):6631-8. doi: 10.1002/adma.201601273. Epub 2016 May 17.

Authors

Affiliations

¹ Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, CA, 94305, USA.
² Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, CA, 94305, USA.
³ Energy Lab, Samsung Advanced Institute of Technology, 130, Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16678, South Korea.
⁴ Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2757 Sand Hill Road, Menlo Park, CA, 94025, USA.

PMID: 27187238
DOI: 10.1002/adma.201601273

Abstract

Ex situ transmission X-ray microscopy reveals micrometer-scale state-of-charge heterogeneity in solid-solution Li1- x Ni1/3 Co1/3 Mn1/3 O2 secondary particles even after extensive relaxation. The heterogeneity generates overcharged domains at the cutoff voltage, which may accelerate capacity fading and increase impedance with extended cycling. It is proposed that optimized secondary structures can minimize the state-of-charge heterogeneity by mitigating the buildup of nonuniform internal stresses associated with volume changes during charge.

Keywords: X-ray microscopy; capacity fade; lithium-ion batteries; positive electrode; stress.