Initial observations of NMC811 by X-ray diffraction show an expansion in the c-lattice parameter followed by a drastic reduction shortly after 4.1 V vs Li/Li + , often termed the lattice collapse. Upwards of 4.1 V, delithiation is significant enough to reduce the interlayer spacing between TM-oxygen layers to less than that of a fully lithiated lattice. The evolution in the a and c-lattice parameters coincides with a total unit cell volumetric reduction; during charging, the removal of lithium causes a contraction in the TM-O bond length from 2.87 to 2.81 Å, manifesting in a shrinkage of the a-lattice parameter. This has been reported to be due to charge compensation where Ni(II) oxidises to Ni(IV) and thus has a greater covalent attraction to its surrounding oxygen atoms. It is believed that this collapse then requires an additional energetic contribution to intercalate lithium back into the structure, consequently increasing the stress on the lattice. These extensive volume fluctuations have been suggested as an origin for electrochemically mediated crack formation. Cracking in secondary particles has been proposed to cause reduced performance due to insufficient connection between particles and the conductive architecture in the electrode matrix, as well as fresh surface exposure to electrolyte and subsequent oxygen release accompanied by electrolyte oxidation. It has been determined that the significant expansion and contraction of the c-lattice parameter during cycling will induce strains on the cathode secondary particles, resulting in the possible development of micro-cracks. As suggested above, the considerable changes in lattice parameters are likely to be a cause of cracking and can advance degradation severely especially during fast charge cycles that sees substantial changes in crystallographic pa-rameter in a short space of time. Additional investigations have prompted a look at the origins of crack formation, showing that cracks may not be solely mediated by crystallographic activity. Indeed, approximately 1/3 of all samples investigated had fabrication-induced cracking in particles due to other physical stresses such as calendaring, winding, or defects during synthesis. This also indicated an increased number of particles with larger cracks to be located towards the separator interface before cycling and correlated any new cracks to the c-lattice collapse. This directionality could be a feature of electrochemically mediated cracking and wrongly correlated if the initial state of the particle is unknown.