TY - JOUR
T1 - An in-depth understanding of chemomechanics in Ni-rich layered cathodes for lithium-ion batteries
AU - Yoon, Sangho
AU - Park, Hyun Gyu
AU - Koo, Sojung
AU - Hwang, Juncheol
AU - Lee, Youbean
AU - Park, Kwangjin
AU - Kim, Duho
N1 - Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2023/4/5
Y1 - 2023/4/5
N2 - Anisotropic lattice variations in Ni-rich layered oxides of lithium-ion batteries (LIBs) have been investigated extensively to suppress the chemomechanics and achieve high energy density with long-term cycling stability. However, an in-depth understanding of the anisotropy is lacking and is very important in the design of high-performance Ni-rich cathodes. Therefore, we reinvestigate the fundamentals of anisotropic lattice variations in Li [Ni10/12Mn1/12Co1/12]O2 (NCM) to understand the correlation between cycling stability degradation at high rate and intergranular microcrack generation between the primary particles, which is confirmed as follows: first, the capacity retention of the NCM under 4.3 V cutoff voltage (NCM4.3V) is much poorer than that under 3.8 V (NCM3.8V); this is described by various electrochemical analyses showing the multiple phase transitions accompanying anisotropic lattice variations and structural collapse. These structural evolutions are clearly observed in the ex situ X-ray diffraction patterns. Second, the resistance of NCM4.3V increases at a faster rate than that of NCM3.8V upon cycling, which supports the direct evidence regarding intergranular microcracks in the cycled particles of NCM4.3V. Third, the nonlinear lattice change in the c direction plays a critical role in accelerating cycling stability degradation. Fourth, serious lattice changes originate from the cationic repulsions between the Li and Ni ions with the electrostatic repulsion of oxygen ions. This mechanism is universally expected in Ni-rich layered oxides; furthermore, these findings provide insights into design strategies that mitigate chemomechanical degradations caused by long-term cycling stabilities in LIBs.
AB - Anisotropic lattice variations in Ni-rich layered oxides of lithium-ion batteries (LIBs) have been investigated extensively to suppress the chemomechanics and achieve high energy density with long-term cycling stability. However, an in-depth understanding of the anisotropy is lacking and is very important in the design of high-performance Ni-rich cathodes. Therefore, we reinvestigate the fundamentals of anisotropic lattice variations in Li [Ni10/12Mn1/12Co1/12]O2 (NCM) to understand the correlation between cycling stability degradation at high rate and intergranular microcrack generation between the primary particles, which is confirmed as follows: first, the capacity retention of the NCM under 4.3 V cutoff voltage (NCM4.3V) is much poorer than that under 3.8 V (NCM3.8V); this is described by various electrochemical analyses showing the multiple phase transitions accompanying anisotropic lattice variations and structural collapse. These structural evolutions are clearly observed in the ex situ X-ray diffraction patterns. Second, the resistance of NCM4.3V increases at a faster rate than that of NCM3.8V upon cycling, which supports the direct evidence regarding intergranular microcracks in the cycled particles of NCM4.3V. Third, the nonlinear lattice change in the c direction plays a critical role in accelerating cycling stability degradation. Fourth, serious lattice changes originate from the cationic repulsions between the Li and Ni ions with the electrostatic repulsion of oxygen ions. This mechanism is universally expected in Ni-rich layered oxides; furthermore, these findings provide insights into design strategies that mitigate chemomechanical degradations caused by long-term cycling stabilities in LIBs.
KW - Anisotropic lattice variation
KW - Cathode
KW - Intergranular crack
KW - Lithium-ion battery
KW - Ni-rich layered oxide
UR - http://www.scopus.com/inward/record.url?scp=85145737156&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2022.168531
DO - 10.1016/j.jallcom.2022.168531
M3 - Article
AN - SCOPUS:85145737156
SN - 0925-8388
VL - 939
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 168531
ER -