title: Surface reconstruction and chemical evolution of stoichiometric layered cathode materials for lithium-ion batteries.
abstract: The present study sheds light on the long-standing challenges associated with high-voltage operation of LiNi(x)Mn(x)Co(1-2x)O2 cathode materials for lithium-ion batteries. Using correlated ensemble-averaged high-throughput X-ray absorption spectroscopy and spatially resolved electron microscopy and spectroscopy, here we report structural reconstruction (formation of a surface reduced layer, to transition) and chemical evolution (formation of a surface reaction layer) at the surface of LiNi(x)Mn(x)Co(1-2x)O2 particles. These are primarily responsible for the prevailing capacity fading and impedance buildup under high-voltage cycling conditions, as well as the first-cycle coulombic inefficiency. It was found that the surface reconstruction exhibits a strong anisotropic characteristic, which predominantly occurs along lithium diffusion channels. Furthermore, the surface reaction layer is composed of lithium fluoride embedded in a complex organic matrix. This work sets a refined example for the study of surface reconstruction and chemical evolution in battery materials using combined diagnostic tools at complementary length scales.
authors.affiliation: Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Lin
authors.affiliation: 1] Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Isaac M
authors.initials: IM
authors.lastname: Markus
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Nordlund
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Tsu-Chien
authors.initials: TC
authors.lastname: Weng
authors.affiliation: Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Asta
authors.affiliation: Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Huolin L
authors.initials: HL
authors.lastname: Xin
authors.affiliation: Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Marca M
authors.initials: MM
authors.lastname: Doeff
mesh_terms: D003035:Cobalt / Q000737:chemistry; D025802:Electric Capacitance; D011211:Electric Power Supplies; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D007477:Ions / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D017348:Microscopy, Electron, Scanning Transmission; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D010316:Particle Size; D013499:Surface Properties; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D007477:Ions; D010087:Oxides; D003035:Cobalt; D008345:Manganese; D009532:Nickel; D008094:Lithium; D014025:Titanium