Nickel-Rich Cathode Material Doping for High-Temperature Cycle Stability
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Solution Overview
Problem
Lithium-ion secondary batteries using nickel-containing lithium composite oxides exhibit poor high-temperature cycling performance due to structural instability of the positive electrode active material.
Innovation Solution
A positive electrode active material composed of secondary particles formed by agglomerated primary particles, where the primary particles include a layered nickel-containing lithium composite oxide with a doping element, maintaining a maximum shrinkage rate of Δamax≤3.00% in the a-axis direction and Δcmax≤3.02% in the c-axis direction during delithiation, enhancing structural stability and preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nickel-containing lithium composite oxide is used as positive electrode active material, then energy density is improved, but high-temperature cycling performance deteriorates due to structural instability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the lattice shrinkage rate (Δa≤3.00%) and swelling rate (Δc≤3.02%) of the nickel-containing lithium composite oxide during delithiation. By adjusting these structural parameters through doping with elements such as Al, Ti, or Zr at the lithium site, the material achieves both high energy density and improved high-temperature cycling performance, resolving the contradiction between energy density and reliability.
2Quantity of substance
If high nickel content is used in lithium composite oxide, then capacity performance is improved, but structural stability deteriorates leading to particle cracking
Solution Approach 1:
The patent employs composite materials by combining nickel-containing lithium composite oxide with doping elements (Al, Ti, Zr) at the lithium site. This composite structure maintains the high capacity performance of nickel while the doping elements provide structural support, preventing particle cracking and improving overall structural stability during cycling.
Solution Approach 2:
The patent applies local quality by selectively doping specific sites (lithium site) within the crystal structure rather than uniformly modifying the entire material. This localized doping approach allows the nickel-rich regions to maintain high capacity while the doped regions provide structural stability, resolving the contradiction between capacity performance and structural stability.
3Reliability
If lattice shrinkage rate is reduced to improve structural stability, then high-temperature cycling performance is improved, but may affect lithium ion diffusion
Solution Approach 1:
The patent optimizes the lattice shrinkage rate parameter to a specific range (Δa≤3.00%) that balances structural stability and lithium ion diffusion. This precise parameter control ensures that the lattice contracts sufficiently to maintain structural integrity at high temperatures while leaving adequate pathways for lithium ion transport, thus resolving the contradiction between reliability and speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the energy density and high-temperature cycling performance of the lithium-ion secondary battery by maintaining structural integrity and preventing cracks in the positive electrode active material, ensuring consistent lithium ion migration and diffusion.
Implementation Method 1
the nickel-containing lithium composite oxide also includes the doping element, and during delithiation, a lattice of the primary particles has a relatively small shrinkage rate along the a-axis direction and swelling rate along the c-axis direction, which improves structural stability
Implementation Method 2
Lithium-ion secondary batteries are rechargeable batteries that operate mainly depending on migration of lithium ions between a positive electrode and a negative electrode
Implementation Method 3
ensuring consistent lithium ion migration and diffusion
Data Source
AI summary
A positive electrode active material and a preparation method thereof, a positive electrode plate, a lithium-ion secondary battery, and a battery module, a battery pack, and apparatus containing the lithium-ion secondary battery are provided. The positive electrode active material includes secondary particles formed by agglomeration of primary particles, where the primary particles include a layered nickel-containing lithium composite oxide, and the nickel-containing lithium composite oxide includes a doping element; and when the positive electrode active material is charged from an 11% delithiated state to a 78% delithiated state at a rate of 0.1 C, a lattice of the primary particles has a maximum shrinkage rate satisfying Δamax≤3.00% in an a-axis direction, and a maximum swelling rate satisfying Δcmax≤3.02% in a c-axis direction.