• 文献标题:   Elucidating and Mitigating High-Voltage Interfacial Chemomechanical Degradation of Nickel-Rich Lithium-Ion Battery Cathodes via Conformal Graphene Coating
  • 文献类型:   Article
  • 作  者:   LUU NS, LIM JM, TORRESCASTANEDO CG, PARK KY, MOAZZEN E, HE K, MEZA PE, LI WY, DOWNING JR, HU XB, DRAVID VP, BARNETT SA, BEDZYK MJ, HERSAM MC
  • 作者关键词:   battery cathode, lithium nickel manganese cobalt oxide, electrochemical creep, cycle life, high voltage, chemomechanical degradation, coulombic efficiency
  • 出版物名称:   ACS APPLIED ENERGY MATERIALS
  • ISSN:   2574-0962
  • 通讯作者地址:  
  • 被引频次:   8
  • DOI:   10.1021/acsaem.1c01995 EA SEP 2021
  • 出版年:   2021

▎ 摘  要

Lithium nickel manganese cobalt oxides (NMCs) are promising cathode materials for high-performance lithium-ion batteries. Although these materials are commonly cycled within mild voltage windows (up to 4.3 V vs Li/Li+), operation at high voltages (>4.7 V vs Li/Li+) to access additional capacity is generally avoided due to severe interfacial and chemomechanical degradation. At these high potentials, NMC degradation is caused by exacerbated electrolyte decomposition reactions and non-uniform buildup of chemomechanical strains that result in particle fracture. By applying a conformal graphene coating on the surface of NMC primary particles, we find significant enhancements in the high-voltage cycle life and Coulombic efficiency upon electrochemical cycling. Postmortem X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy suggest that the graphene coating mitigates electrolyte decomposition reactions and reduces particle fracture and electrochemical creep. We propose a relationship between the spatial uniformity of lithium flux and particle-level mechanical degradation and show that a conformal graphene coating is well-suited to address these issues. Overall, these results delineate a pathway for rationally mitigating high-voltage chemomechanical degradation of nickel-rich cathodes that can be applied to existing and emerging classes of battery materials.