Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

Abstract

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.

Unveiling Nickel Chemistry in Stabilizing High‐Voltage Cobalt‐Rich Cathodes for Lithium‐Ion Batteries

“…As shown by XPS in Figure 4e, the signal of lattice O 2− has a strong peak at ≈530 eV in pristine LCO and LCNO. As illustrated in Figure 4g, consistent trend is also found in TOF-SIMS mapping, showing less accumulation of CEIs species (e.g., 7 LiF 2 − , C 3 OF − , CoF 3 − , CH 3 O − , C 2 HO − , and C 2 F − from electrolyte decomposition) [53,54] on the surface of LCNO than that of LCO (for more details, see Figures S22 and S23 and Table S6, Supporting Information). Similarly, there is weaker intensity for the peak at ≈56 eV (from Li 1s orbital of Li-containing compound, such as resistive LiF and Li 2 CO 3 ) in cycled LCNO than in cycled LCO.…”

Prospect and Reality of Ni‐Rich Cathode for Commercialization

“…Reproduced with permission. [157] Copyright 2017, Macmillan Publishers Limited. b-d) SEM images of the single crystalline nickel-rich cathodes synthesized by different synthetic methods.…”

“…In general, the coprecipitated precursor consisted of the secondary particle, therefore, the chemical reagent was necessary for each grain growth at lower temperature (Figure 18a). [120,157] The representative synthetic method was the flux growth method. It is well known that the flux growth method provides highly developed oxide compounds at low temperature compared with the solid-state reactions.…”

An Outlook on Lithium Ion Battery Technology

“…An in-depth characterization of LiNi 0.7 Mn 0.15 Co 0.15 O 2 (NMC-71515), before and after cycling in 1 M LiPF 6 in EC-DEC electrolyte, with a combination of X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), and high-resolution transmission electron microscopy (HR-TEM) reveals that the SEI layer from the cathode surface to the exterior is successively composed of the rock salt Li x Ni 1– x O phase, transition-metal fluorides formed by dissolved metal ions, and organic liquid electrolyte decomposition products. 36 Also, the SEI layer grows continuously with cycling. Figure 4a illustrates a TOF-SIMS chemical mapping of the organic electrolyte decomposition products ( 7 Li 2 + / 7 Li 2 F and 7 LiF 2 – ) and transition-metal fluorides (MnF 3 – ) on a secondary particle of NMC-71515 cathode after cycling.…”