%0 Journal Article
%A Yanying Lu
%A Tianyu Zhu
%A Eric J McShane
%A Bryan D McCloskey
%A Guoying Chen
%B Small
%D 2022
%G eng
%N 12
%P 2105833
%R 10.1002/smll.202105833
%T Single‐Crystal LiNixMnyCo1−x−yO2 Cathodes for Extreme Fast Charging
%U https://onlinelibrary.wiley.com/toc/16136829/18/12
%V 18
%8 03/2022
%! Small
%X <p><span>Ni-rich layered LiNi</span><sub><em><span>x</span></em></sub><span>Mn</span><sub><em><span>y</span></em></sub><span>Co</span><sub><span>1−</span><em><span>x</span></em><span>−</span><em><span>y</span></em></sub><span>O</span><sub><span>2</span></sub><span>&nbsp;(NMCs,&nbsp;</span><em>x</em><span>&nbsp;</span><span>≥</span><span>&nbsp;0.8) are poised to be the dominating cathode materials for lithium-ion batteries for the foreseeable future. Conventional polycrystalline NMCs, however, suffer from severe cracking along the grain boundaries of primary particles and capacity loss under high charge and/or discharge rates, hindering their implementation in fast-charging electric vehicular (EV) batteries. Single-crystal (SC) NMCs are attractive alternatives as they eliminate intergranular cracking and allow for grain-level surface optimization for fast Li transport. In the present study, the authors report synthetic approaches to produce SC LiNi</span><sub><span>0.8</span></sub><span>Co</span><sub><span>0.1</span></sub><span>Mn</span><sub><span>0.1</span></sub><span>O</span><sub><span>2</span></sub><span>&nbsp;(NMC811) samples with different morphologies: Oct-SC811 with predominating (012)-family surface and Poly-SC811 with predominating (104)-family surface. Poly-SC811, representing the first experimentally synthesized NMC811 single crystals with (104) surface, delivers superior performance even at the ultra-high rate of 6 C. Through detailed X-ray analysis and electron microscopy characterization, it is shown that the enhanced performance originates from better chemical and structural stabilities, faster Li</span><span>+</span><span>&nbsp;diffusion kinetics, suppressed side reactions with electrolyte, and excellent cracking resistance. These insights provide important design guidelines in the future development of fast-charging NMC-type cathode materials.</span></p>