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Operando Bragg coherent diffraction imaging of LiNi0.8Mn0.1Co0.1O2 primary particles within commercially printed NMC811 electrode sheets

DOI: 10.1021/acsnano.0c08575 DOI Help

Authors: Ana Katrina C. Estandarte (University College London) , Jiecheng Diao (University College London) , Alice Llewellyn (University College London; The Faraday Institution) , Anmol Jnawali (University College London) , Thomas M. M. Heenan (University College London; The Faraday Institution) , Sohrab R. Daemi (University College London) , Josh J. Bailey (University College London; The Faraday Institution) , Silvia Cipiccia (Diamond Light Source) , Darren Batey (Diamond Light Source) , Xiaowen Shi (Diamond Light Source) , Christoph Rau (Diamond Light Source) , Dan J. L. Brett (University College London; The Faraday Institution) , Rhodri Jervis (University College London; The Faraday Institution) , Ian K. Robinson (University College London; The Faraday Institution) , Paul Shearing (University College London; The Faraday Institution)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Nano

State: Published (Approved)
Published: December 2020
Diamond Proposal Number(s): 25852 , 25440 , 24129 , 22373 , 22309 , 21652

Abstract: Due to complex degradation mechanisms, disparities between the theoretical and practical capacities of lithium-ion battery cathode materials persist. Specifically, Ni-rich chemistries such as LiNi0.8Mn0.1Co0.1O2 (or NMC811) are one of the most promising choices for automotive applications; however, they continue to suffer severe degradation during operation that is poorly understood, thus challenging to mitigate. Here we use operando Bragg coherent diffraction imaging for 4D analysis of these mechanisms by inspecting the individual crystals within primary particles at various states of charge (SoC). Although some crystals were relatively homogeneous, we consistently observed non-uniform distributions of inter- and intracrystal strain at all measured SoC. Pristine structures may already possess heterogeneities capable of triggering crystal splitting and subsequently particle cracking. During low-voltage charging (2.7–3.5 V), crystal splitting may still occur even during minimal bulk deintercalation activity; and during discharging, rotational effects within parallel domains appear to be the precursor for the nucleation of screw dislocations at the crystal core. Ultimately, this discovery of the central role of crystal grain splitting in the charge/discharge dynamics may have ramifications across length scales that affect macroscopic performance loss during real-world battery operation.

Journal Keywords: Li ion; X-ray; synchrotron; CDI; NMC811; operando; electric vehicle

Subject Areas: Materials, Chemistry, Energy

Instruments: I13-1-Coherence