High-Ni Cathode Material with Ordered Crystal Structure
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Solution Overview
Problem
Existing positive electrode active materials with high Ni content suffer from reduced battery performance due to Ni2+ occupying Li+ sites in the crystal lattice, leading to high capacity fade during cycling, and are often accompanied by high LiOH impurities that degrade performance.
Innovation Solution
A positive electrode active material with a specific composition and controlled cooling profile during manufacturing, ensuring a well-ordered crystal structure and reduced LiOH content, achieved through a method involving heating and gradual cooling to optimize the (003)/(104) peak ratio in XRD diffractograms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high Ni content (x≥70.0 mol %) is used in the positive electrode active material, then the battery capacity increases, but Ni2+ occupies Li+ sites in the crystal lattice causing capacity fade during cycling
Solution Approach 1:
The patent applies local quality by introducing element A at specific crystallographic positions (such as the 2a site in R-3m structure or specific sites in H2-P3̄m1 structure) to stabilize the local environment around Li+ sites. This localized modification prevents Ni2+ migration to Li+ sites while preserving the high-capacity characteristics of the bulk high-Ni material, thereby resolving the contradiction between high capacity and cycling stability.
Solution Approach 2:
The patent employs preliminary action by pre-stabilizing the crystal structure through the strategic placement of element A before cycling begins. The element A is incorporated into the lattice during synthesis to create a stable framework that prevents structural degradation and cation mixing during subsequent electrochemical cycling, thus maintaining capacity stability from the outset.
2Quantity of substance
If high Ni content is used, then the battery capacity increases, but LiOH impurities increase degrading performance
Solution Approach 1:
The patent applies parameter changes by optimizing the synthesis conditions including temperature (800-1000°C), atmosphere control, and stoichiometry to minimize LiOH formation. By precisely controlling these parameters during the sintering process, the patent achieves low LiOH content while maintaining high Ni content and excellent electrochemical performance.
3Reliability
If the crystal structure is well ordered, then the battery performance improves, but achieving low cation mixing requires additional processing steps
Solution Approach 1:
The patent merges the structure-directing function of element A with the electroactive components of the cathode material. By incorporating element A into the bulk crystal structure rather than as a surface coating or separate phase, the patent achieves structure optimization and cation site stabilization in a single integrated material system, eliminating the need for separate structure-modification processing steps.
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 results in improved electrochemical performance and reduced capacity fade, eliminating the need for additional processing steps and minimizing LiOH impurities, thereby enhancing the overall battery performance.
Implementation Method 1
an X-Ray diffractogram, obtained from a Cu K-α X-Ray radiation source, of the positive electrode active material has a (003) peak located at 2θ=17.0° to 20.0° and (104) peak located at 2θ=43.0° to 46.0°
Implementation Method 2
A positive electrode active material with a specific composition and controlled cooling profile during manufacturing, ensuring a well-ordered crystal structure and reduced LiOH content, achieved through a method involving heating and gradual cooling
Data Source
AI summary
Positive electrode active material comprising lithium, a metal other than lithium and oxygen, wherein the metal has a composition M, wherein M consists of Ni in a content x, Mn in a content y, Co in a content z, and A in a content a, wherein x, y, z, and a are expressed as molar contents, wherein x+y+z+a=100%, wherein x≥70.0%, wherein 0≤y≤30.0%, wherein 0≤z≤30.0%, wherein 0≤a≤2.0%, wherein an X-Ray diffractogram of the positive electrode active material has a (003) peak located at 2θ=17.0° to 20.0° and (104) peak located at 2θ=43.0° to 46.0°, wherein the ratio (maximum intensity of the (003) peak)/(maximum intensity of the (104) peak) is at least 1.530.