Thermally-driven mesopore formation and oxygen release in delithiated NCA cathode particles

Abstract

The structural integrity of layered Ni-rich oxide cathode materials is one of the most essential factors that critically affect the performance and reliability of lithium-ion batteries.

Long-term chemothermal stability of delithiated NCA in polymer solid-state batteries

“…Only samples subjected to 4 months of aging at 80 C show a clear reduction in the measured nickel oxidation state, which does not substantially change further when samples are kept at 80 C for 1 year. This observation is in good agreement with our previous study, where we demonstrated the short-term thermal stability of Li 0.3 NCA at 200 C. 17…”

“…Our results indicate that the phase transformation, and the associated nickel reduction, starts at the surface and propagates into the bulk material with increased aging time, in accordance with the literature. 44 Our previous study showed the onset of oxygen evolution from Li 0.3 NCA occurs at 200 C using TGA-MS. 17 Although in this study samples are stored at 60-90 C, it cannot be ruled out that a small amount of oxygen escapes from the surface at these temperatures and long storage times, initiating decomposition at the surface. The release of oxygen from the crystal lattice may be exacerbated at a low partial oxygen pressure, i.e., the storage in an inert atmosphere as was done in this study.…”

“…We have also studied cycling induced cracking, and SOC reduction within the bulk NCA material in poly(ethylene oxide) (PEO)-based polymer solid-state batteries, due to intergranular cracking. 17,18 Herein, we report on the degradation of NCA induced by the presence of individual electrode components, i.e., polymer and lithium salt. We also studied the inuence of polymer and lithium salt combinations on chemothermal NCA degradation.…”

Lattice Oxygen Instability in Oxide‐Based Intercalation Cathodes: A Case Study of Layered LiNi1/3Co1/3Mn1/3O2

“…[ 1,11 ] The loss of lattice oxygen in cathodes causes microscopic and macroscopic structural changes, for example order to disorder, [ 12,13 ] phase transition from layered rock‐salt to spinel, [ 12 ] irreversible decomposition, [ 14,15 ] and fracture of particle morphology. [ 16,17 ] The structural degradation inevitably results in unintended energy loss and sluggish reaction kinetics during charge and discharge, thus in deterioration of electrochemical performance. Moreover, a series of exothermic reactions between gaseous oxygen released from the cathode materials (or reactive lattice oxygen) with organic electrolytes causes gas generation, for example, CO, CO 2 , heat accumulation, and trigger thermal runaway.…”

Surface/Interface Structure Degradation of Ni‐Rich Layered Oxide Cathodes toward Lithium‐Ion Batteries: Fundamental Mechanisms and Remedying Strategies

“…Therefore, within the past decades, worldwide efforts focusing on the surface/interface modifications have been devoted to regulate the chemical and/or physical properties of the cathodes. [35][36][37][38] More significantly, microstructure degradation during accelerated calendar aging [39,40] structural evolution under high voltages [41][42][43][44][45][46] and elevated temperature conditions [41,[47][48][49][50] and oxygen release phenomenon [1,46,[51][52][53][54] as well as several new insights into the cation disorder [55][56][57] concerning the Ni-rich cathodes have been lately uncovered by various means. A comprehensive summary of the advancements in the field of Ni-rich cathodes has been reported recently, [2,6,12,14,16,36,[58][59][60][61][62] but an overview of the fundamental origins governing these surface/interface behaviors has yet to be completely realized.…”