Cathode Grain Cracking: Single-Crystal vs Polycrystalline NMC

A key open problem in battery materials discovery is why layered-oxide (NMC) cathode particles lose capacity over hundreds of charge/discharge cycles. This simulator renders a 3D cathode secondary particle as hundreds of randomly-oriented primary grains and drives it through repeated charge/discharge cycles using the real anisotropic c-axis/a-axis lattice-strain curve of a layered oxide, including the sharp H2→H3 contraction near 80% state of charge. Because neighboring grains are misoriented, the same intrinsic strain pulls each grain boundary a different way, accumulating fatigue damage that eventually cracks the weakest boundaries — switch to a single-crystal particle to see why that failure mode disappears when there are no grain boundaries left to crack, and use the depth-of-discharge and C-rate controls to see how cycling protocol changes how fast a real cell's capacity retention falls.