Revealing Anisotropic Spinel Formation on Pristine Li‐ and Mn‐Rich Layered Oxide Surface and Its Impact on Cathode Performance. Issue 11 (6th January 2017)

• Record Type: Journal Article
• Authors: Kuppan, Saravanan; Shukla, Alpesh Khushalchand; Membreno, Daniel; Nordlund, Dennis; Chen, Guoying
• Is Part Of: Advanced energy materials. Volume 7:Issue 11(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-01-06
• Subjects: Li and Mn‐rich layered oxide -- lithium‐ion battery cathode -- microscopy and spectroscopy -- particle morphology -- surface properties; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.201602010
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract : Surface properties of cathode particles play important roles in the transport of ions and electrons and they may ultimately dominate cathode's performance and stability in lithium‐ion batteries. Through the use of carefully prepared Li1.2 Ni0.13 Mn0.54 Co0.13 O2 crystal samples with six distinct morphologies, surface transition‐metal redox activities and crystal structural transformation are investigated as a function of surface area and surface crystalline orientation. Complementary depth‐profiled core‐level spectroscopy, namely, X‐ray absorption spectroscopy, electron energy loss spectroscopy, and atomic‐resolution scanning transmission electron microscopy, are applied in the study, presenting a fine example of combining advanced diagnostic techniques with a well‐defined model system of battery materials. The present study reports the following findings: (1) a thin layer of defective spinel with reduced transition metals, similar to what is reported on cycled conventional secondary particles in the literature, is found on pristine oxide surface even before cycling, and (2) surface crystal structure and chemical composition of both pristine and cycled particles are facet dependent. Oxide structural and cycling stabilities improve with maximum expression of surface facets stable against transition‐metal reduction. The intricate relationships among morphology, surface reactivity and structural transformation, electrochemical performance, and stability of the cathode materials are revealed. Abstract : Particle morphology controls elemental, chemical, and structural makeups of both pristine and cycled oxide surface. Cathode structural and cycling stabilities improve with maximum expression of surface facets resistant to transition‐metal reduction.