Accumulated Lattice Strain as an Intrinsic Trigger for the First-Cycle Voltage Decay in Li-Rich 3d Layered Oxides

Suning Wang; Tian Zhao; Jinniu Chen; Alexander Missyul; Laura Simonelli; Laijun Liu; Fujun Li; Xiangyang Kong; Weibo Hua

doi:10.1021/acsami.3c02907

Accumulated Lattice Strain as an Intrinsic Trigger for the First-Cycle Voltage Decay in Li-Rich 3d Layered Oxides

ACS Appl Mater Interfaces. 2023 Apr 26;15(16):20200-20207. doi: 10.1021/acsami.3c02907. Epub 2023 Apr 13.

Authors

Suning Wang^{1

2

3}, Tian Zhao¹, Jinniu Chen¹, Alexander Missyul⁴, Laura Simonelli⁴, Laijun Liu³, Fujun Li⁵, Xiangyang Kong⁶, Weibo Hua^{1

7

2

5}

Affiliations

¹ School of Chemical Engineering and Technology, Xi'an Jiaotong University, No.28, West Xianning Road, Xi'an, Shaanxi 710049, China.
² Institute for Applied Materials (IAM), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
³ College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China.
⁴ CELLS-ALBA Synchrotron, Cerdanyola del Valles, Barcelona E-08290, Spain.
⁵ Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, China.
⁶ School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
⁷ School of Chemical Engineering, Sichuan University, No. 24 South Section 1, Yihuan Road, 610065 Chengdu, China.

PMID: 37052376
DOI: 10.1021/acsami.3c02907

Abstract

Li- and Mn-rich layered oxides (LMLOs) are promising cathode materials for Li-ion batteries (LIBs) owing to their high discharge capacity of above 250 mA h g^-1. A high voltage plateau related to the oxidation of lattice oxygen appears upon the first charge, but it cannot be recovered during discharge, resulting in the so-called voltage decay. Disappearance of the honeycomb superstructure of the layered structure at a slow C-rate (e.g., 0.1 C) has been proposed to cause the first-cycle voltage decay. By comparing the structural evolution of Li[Li_0.2Ni_0.2Mn_0.6]O₂ (LLNMO) at various current densities, the operando synchrotron-based X-ray diffraction results show that the lattice strain in bulk LLNMO is continuously increased over cycling, resulting in the first-cycle voltage loss upon Li-ion insertion. Unlike the LLNMO, the accumulated average lattice strain of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) and LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) from the open-circuit voltage to 4.8 V could be released on discharge. These findings help to gain a deep understanding of the voltage decay in LMLOs.

Keywords: Li-rich cathodes; lattice strain accumulation; layered structure; operando X-ray diffraction; voltage decay.