Low-Cobalt Ternary Cathode Composition to Limit High-Voltage Cracking

The patent applies local quality by creating a core-shell structure where the surface layer has different composition and properties than the core. The surface is enriched with nickel and modified with aluminum and oxygen to prevent disordering, while the core maintains high nickel content for capacity. This localized differentiation allows high nickel content throughout while protecting against lithium-nickel disordering at critical interfaces.

The patent uses composite materials by combining multiple elements (Ni, Co, Mn, Al, O) in a layered structure. The composite consists of a Ni-rich core phase and an Al-O modified surface phase, creating a multi-phase composite that leverages the high capacity of nickel while using aluminum and oxygen to stabilize the structure and prevent degradation mechanisms.

The patent applies beforehand cushioning by pre-modifying the surface with aluminum and oxygen before cycling begins. This surface modification creates a protective layer that cushions against the mechanical stress of volume contraction during delithiation. The modified surface layer absorbs and distributes the stress, preventing crack initiation and propagation that would otherwise occur at high cut-off voltages.

The patent changes parameters by modifying the surface composition and structure through aluminum doping and oxygen enrichment. This parameter change creates a surface layer with different mechanical and electrochemical properties that can withstand high voltage cycling. The surface modification alters the local stoichiometry and bonding, creating a more resilient structure that maintains integrity during excessive lithium extraction.

The patent applies taking out by selectively removing cobalt from the bulk composition while concentrating stabilizing elements (aluminum and oxygen) at the surface. This extraction of cobalt from the overall formula reduces cost, while the surface enrichment with alternative stabilizing elements compensates for the loss of cobalt's structural stabilization function. The surface-modified structure provides the needed stability without requiring high bulk cobalt content.

The patent uses cheap short-living objects by replacing expensive cobalt with cheaper aluminum and oxygen at the surface. While aluminum and oxygen individually provide less stabilization than cobalt, their combination in the surface layer creates sufficient stability for cycling applications, achieving cost reduction while maintaining acceptable performance through this element substitution strategy.