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Abstract BackgroundMechanical degradation of electrodes driven by electrochemical reactions limits battery performance and longevity. While various microstructures of LiNi_xMn_yCo_zO₂(NMC) cathodes have been developed, their comparative mechanical properties and chemomechanical degradation are unknown. ObjectiveThis study measures the mechanical properties of NMC cathode particles of three different microstructures: gravel-type NMC of large grains, gravel NMC of small grains, and rod-shaped NMC. Damage evolution in the NMC particles is simulated using finite element modeling. MethodsWe use flat punch indentation to measure the particle strength, contact modulus, and fracture energy of NMC particles of different microstructures. We also assess the effect of voids on the mechanical properties and damage generation in NMC particles upon cycles. ResultsThe particle strength dictated by grain boundaries is measured to be ~ 200 MPa in the three NMC microstructures. The contact modulus changes nonlinearly during mechanical load. The fracture energy of gravel NMC particles is ~ 0.5 J/m². The presence of voids compromises the mechanical properties of NMC particles, but it helps delocalize stress within the particles and reduces damage generation upon electrochemical cycles. ConclusionsThe combined experiments and modeling provide a comprehensive analysis of the mechanical behaviors and their implications on chemomechanical degradation of NMC cathode particles of various microstructures. 

Abstract Natural levees form through sediment delivery from channels, dispersal onto floodplains, and storage at channel margins. When levees breach, they release water and sediment onto the floodplain, occasionally causing river avulsions. Despite their significance, levee growth remains poorly understood, and no existing models capture the dynamic channel‐levee evolution systems. A common assumption is that levee and channel bed aggradation rates are coupled or equal; however, this cannot be true because levees do not accumulate everywhere along aggrading channel belts. Using a one‐dimensional numerical model, we investigate levee growth decoupled from channel bed aggradation under flood scenarios wherein the flooded level: (a) exceeds the levee crest height (i.e., front loading); or (b) is lower than the levee crest partially inundating distal levee deposits (i.e., back loading). Front loading events initially aggrade the levee crest, which confines the channel, increases bankfull depth, and reduces flooding. During confinement, levee growth restricts flooding, and minor back loading events are more common. Over this period, the channel bed aggrades until bankfull depth decreases sufficiently to trigger larger floods. This channel‐releasing process increases flood likelihood and enhances overbank accumulation, promoting front loading and re‐confining the channel. Our findings suggest aggradational channels may experience confined‐release phases characterized by episodic levee growth and fluctuating bankfull depth. Rapid in‐channel aggradation increases flood frequency and variability with more confined‐release cycles. These results imply that river avulsions and associated floods might preferentially occur when the channel bed aggrades faster than adjacent levees, whereby the channel becomes shallower and destabilized.