Layered Cathode Composition for Dense High-Nickel Battery Cycling
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Solution Overview
Problem
Lithium-ion batteries face challenges with high-nickel cathode materials that have high bulk density, particle breakage, and gas production under high compaction density, limiting their application in high energy density batteries, especially at high rates and long cycle life.
Innovation Solution
A cathode design featuring a layered structure with first and second particles of specific sizes and compositions, where the second particle is less susceptible to breakage and located further from the current collector, enhancing stability and kinetic performance while reducing gas production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel cathode materials are used to reduce cobalt content and increase capacity, then energy density is improved, but particle breakage and gas production increase under high compaction density
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where a high-nickel cathode material core is coated with a protective layer. This composite structure allows the inner high-nickel material to provide high capacity and energy density while the outer protective layer prevents particle breakage and reduces gas production under compaction density, thus resolving the contradiction between energy density improvement and particle stability maintenance.
2Quantity of substance
If high compaction density is applied to increase energy density, then battery capacity is improved, but particle breakage and gas production increase
Solution Approach 1:
The patent applies beforehand cushioning by introducing a protective coating layer on the cathode particles before assembly into the battery. This protective layer acts as a cushion that absorbs mechanical stress during compaction, preventing particle breakage and reducing gas production even when high compaction density is applied to increase battery capacity. The cushioning effect is established in advance during the coating process.
3Speed
If particle size is reduced to improve kinetics, then rate performance is improved, but surface area increases leading to higher reactivity and potential instability
Solution Approach 1:
The patent applies local quality by creating a non-uniform core-shell structure where the inner core region has high-nickel composition optimized for capacity while the outer shell region has a protective composition optimized for stability. This local differentiation allows small particle size for good kinetics in the core while the protective shell reduces surface reactivity and enhances overall compositional stability, resolving the contradiction between rate performance and compositional stability.
Data Source
AI summary
A cathode includes a cathode current collector; and a cathode active material layer disposed on a surface of the cathode current collector. The cathode active material layer includes a first particle and a second particle, the first particle including a secondary particle composed of a third particle, the third particle being a primary particle, the first particle having an average particle size of 5 μm to 20 μm, the third particle having an average particle size of 200 nm to 700 nm, the second particle including a fourth particle and/or a secondary particle composed of the fourth particle, the fourth particle being a primary particle, the second particle having an average particle size of 3 μm to 5 μm, the fourth particle having an average particle size of 800 nm to 5 μm.