Meaning
Electrochemical endurance characterizes the ability of a positive electrode to maintain its structure and capacity above 4.3 volts. Maintaining high voltage cathode stability prevents the decomposition of the lattice and the oxidation of the surrounding electrolyte. Operating at these increased potentials increases the energy density of the cell by accessing more lithium capacity from the transition metal oxide.
Long term cycling depends on the resistance of the crystal structure to irreversible changes.
Structural Retention
Crystalline lattices undergo stress when large amounts of lithium are removed during charging. Improved high voltage cathode stability limits the migration of transition metal ions into the lithium layers. Doping or surface coatings help pin the structure in place and prevent the collapse of the interlayer spacing.
Electrolyte Compatibility
Oxidative reactions at the interface create thick resistive layers that impede ion flow. Cathode materials with superior high voltage cathode stability minimize the catalytic breakdown of carbonate solvents. Reduced chemical reactivity at the surface prevents the formation of gas and the consumption of active lithium.
Performance Degradation
Capacity loss and voltage drop result from the loss of active surface area. When high voltage cathode stability fails, the internal resistance of the battery rises substantially. Cells that maintain their properties at high voltage offer longer service lives in electric vehicle applications.
