Understanding the roles of tris(trimethylsilyl) phosphite (TMSPi) in LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811)/silicon–graphite (Si–Gr) lithium‐ion batteries

DOI: 10.1002/admi.202000277

Authors: Haidong Liu (Uppsala University) , Andrew Naylor (Uppsala University) , Ashok Sreekumar Menon (Uppsala University) , William R. Brant (Uppsala University) , Kristina Edström (Uppsala University) , Reza Younesi (Uppsala University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Advanced Materials Interfaces , VOL 8

State: Published (Approved)
Published: June 2020
Diamond Proposal Number(s): 23159

Abstract: The coupling of nickel‐rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes with high‐capacity silicon–graphite (Si–Gr) anodes is one promising route to further increase the energy density of lithium‐ion batteries. Practically, however, the cycle life of such cells is seriously hindered due to continuous electrolyte degradation on the surfaces of both electrodes. In this study, tris(trimethylsilyl) phosphite (TMSPi) is introduced as an electrolyte additive to improve the electrochemical performance of the NMC811/Si–Gr full cells through formation of protective surface layers at the electrode/electrolyte interfaces. This is thought to prevent the surface fluorination of the active materials and enhance interfacial stability. Notably, TMSPi is shown to significantly reduce the overpotential and operando X‐ray diffraction (XRD) confirms that an irreversible “two‐phase” transition reaction caused by the formed adventitious Li2CO3 layer on the surface of NMC811 can transfer to a solid‐solution reaction mechanism with TMSPi‐added electrolyte. Moreover, influences of TMSPi on the cathode electrolyte interphase (CEI) on the NMC811 and solid electrolyte interphase (SEI) on the Si–Gr are systematically investigated by electron microscopy and synchrotron‐based X‐ray photoelectron spectroscopy which allows for the nondestructive depth‐profiling analysis of chemical compositions and oxidation states close to the electrode surfaces.

Journal Keywords: additives; lithium‐ion batteries; NMC811/Si–graphite full cells; operando XRD

Diamond Keywords: Batteries; Lithium-ion

Subject Areas: Materials, Chemistry, Energy


Instruments: I09-Surface and Interface Structural Analysis

Added On: 25/06/2020 10:21

Documents:
admi.202000277.pdf

Discipline Tags:

Energy Storage Energy Physical Chemistry Energy Materials Chemistry Materials Science

Technical Tags:

Spectroscopy X-ray Photoelectron Spectroscopy (XPS)