Cobalt-Free Ni-Rich Cathode Material for Crack-Resistant Stability
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Solution Overview
Problem
Existing Ni-based cathode active materials face issues with micro-cracks, structural instability, and electrolyte depletion due to unstable Ni ions, leading to reduced battery performance and high manufacturing costs, especially in cobalt-free formulations.
Innovation Solution
A cathode active material is developed by substituting part of Li with Na, incorporating W, Mg, and Ti, and adding S to stabilize the crystal structure and reduce Ni ion instability, resulting in a single-crystal, single-particle design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-nickel-based cathode active material is synthesized by coprecipitation method to maximize capacity and lower costs, then nickel content increases and manufacturing cost decreases, but micro-cracks occur inside secondary particles during long-term charging/discharging
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core contains high-nickel content (Ni ≥ 50 mol%) for high capacity, while the shell contains stabilizing elements (Co, Mn, Al, Ti, or Zr) that prevent micro-crack formation. This local differentiation allows the high-nickel core to deliver high capacity while the stabilizing shell maintains structural integrity during charging/discharging cycles.
Solution Approach 2:
The patent employs composite materials by combining high-nickel cathode material with stabilizing elements to form a composite structure. The composite consists of a high-nickel phase (for capacity) and a stabilizing phase containing Co, Mn, Al, Ti, or Zr (for structural stability), creating a material that exhibits both high capacity and resistance to micro-cracking.
2Quantity of substance
If electrode density is increased to realize high energy density, then energy density improves, but secondary particles collapse causing electrolyte depletion
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core contains high-nickel content (Ni ≥ 50 mol%) for high capacity, while the shell contains stabilizing elements (Co, Mn, Al, Ti, or Zr) that prevent micro-crack formation. This local differentiation allows the high-nickel core to deliver high capacity while the stabilizing shell maintains structural integrity during charging/discharging cycles.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating stabilizing elements (Co, Mn, Al, Ti, or Zr) into the cathode material structure prior to electrode assembly. These stabilizing elements act as a protective cushion that prevents particle collapse and electrolyte depletion during high-density operation, addressing the problem before it occurs during battery cycling.
3Ease of manufacture
If cobalt content is reduced or eliminated to lower manufacturing costs, then manufacturing cost decreases, but phase stability deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the composition parameters of the cathode material - specifically maintaining nickel content at ≥50 mol% while controlling stabilizing element content (Co, Mn, Al, Ti, or Zr) at 5-50 mol%. This parameter optimization allows reduction of cobalt content for lower cost while maintaining phase stability through the stabilizing effect of alternative elements.
Solution Approach 2:
The patent employs composite materials by combining high-nickel cathode material with stabilizing elements to form a composite structure. The composite consists of a high-nickel phase (for capacity) and a stabilizing phase containing Co, Mn, Al, Ti, or Zr (for structural stability), creating a material that exhibits both high capacity and resistance to micro-cracking.
4Reliability
If single-crystal-type Ni-based cathode active material is used to prevent particle collapse, then particle integrity improves, but structural and thermal instability occurs due to unstable Ni3+ and Ni4+ ions
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core contains high-nickel content (Ni ≥ 50 mol%) for high capacity, while the shell contains stabilizing elements (Co, Mn, Al, Ti, or Zr) that prevent micro-crack formation. This local differentiation allows the high-nickel core to deliver high capacity while the stabilizing shell maintains structural integrity during charging/discharging cycles.
Solution Approach 2:
The patent applies intermediary by introducing stabilizing elements (Co, Mn, Al, Ti, or Zr) as mediator atoms within the cathode material structure. These intermediary elements mediate between the unstable Ni3+/Ni4+ ions and the crystal lattice, stabilizing the structure and preventing Jahn-Teller distortion while allowing the high-nickel composition to maintain particle integrity.
Data Source
AI summary
The present disclosure relates to a cathode active material, a method of preparing the same, and a lithium secondary battery including a cathode including the cathode active material, the cathode active material including: a transition metal (M) other than a Co element, includes at least one element of W, Mg and Ti, and further includes an S element, a preparation method thereof, and a lithium secondary battery including a cathode including the cathode active material.