Interface Interaction Behavior of Self-Terminated Oligomer Electrode Additives for a Ni-Rich Layer Cathode in Lithium-Ion Batteries: Voltage and Temperature Effects

Self-terminated oligomer additives synthesized from bismaleimide and barbituric acid derivatives improve the safety and performance of lithium-ion batteries (LIBs). This study investigates the interface interaction of these additives and the cathode material. Two additives were synthesized by Michael addition (additive A) and aza-Michael addition (additive B). The electrochemical performances of bare and modified LiNi0.6Mn0.2Co0.2O2 (NMC622) materials are studied. The cycling stability and rate capability of NMC622 considerably improve on surface modification with additive B. According to the differential scanning calorimetry results, the exothermic heat of fully deliathiated NMC622 is dramatically decreased through surface modification with both additives. The electrode surface kinetics and interface interaction phenomena of the additives are determined through surface plasma resonance measurements in operando gas chromatography−mass spectroscopy (GCMS) and in situ soft X-ray absorption spectroscopy (XAS). The binding rate constant of additive B onto NMC622 particles is 1.2− 2.3 × 104 M−1 s −1 in the temperature range of 299−311 K, which is ascribed to the strong binding affinity toward the electrode surface. This affinity enhances Li+ diffusion, which allows the electrode modified by additive B to provide high electrochemical performance with superior thermal stability. In operando GCMS reveals that gas evolution due to the electrolyte degradation at the NMC622 surface contributes to safety hazards in the bare NMC622 material. In situ soft XAS indicates the occurrence of structural transformation in the bare NMC622 material after it is fully charged and at elevated temperatures. The NMC622 material is stabilized by incorporating additives. The unique performance of additive B can be attributed to its linear structure that allows superior electrode surface adhesion compared with that of additive A. Therefore, this study presents an optimized working principle of self-terminated oligomers, which can be developed and applied to improve the safety and performance of LIBs.

Publication year: 2019
Authors: Fu-Ming Wang,*,†,‡,§,∥ Tibebu Alemu,† Nan-Hung Yeh,† Xing-Chun Wang,† Yi-Wen Lin,† Chun-Chuan Hsu,† Yung-Jen Chang,† Chia-Hao Liu,† Chiao-I Chuang,† Li-Hao Hsiao,† Jin-Ming Chen,⊥ Shu-Chih Haw,⊥ Wei-Ling Chen,† Quoc-Thai Pham,† and Chia-Hung Su
Affiliations:

† Graduate Institute of Applied Science and Technology and

‡ Sustainable Energy Center, National Taiwan University of Science and Technology, Taipei 10607, Taiwan § Department of Chemical Engineering and ∥ R&D Center for Membrane Technology, Chung Yuan Christian University, Taoyuan 32023, Taiwan

⊥National Synchrotron Radiation Research Center, Hsin-Chu 30076, Taiwan # Graduate School of Biochemical Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan

Published in: ASC Applied Materials and Interfaces
DOI: 10.1021/acsami.9b12123

MP-SPR KEYWORDS

adsorption barbituric acid bismaleimide acid electrode lithium-ion battery refractive index thickness
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