High-Nickel Cathode Material for Stable Electrode Slurries
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Solution Overview
Problem
The aggregation of particles in lithium nickel cobalt manganese-based oxide (NCM oxide) electrode slurries due to Van der Waals forces leads to gelation, affecting the uniformity of the electrode layer, increasing resistance, and reducing capacity and lifespan of lithium secondary batteries.
Innovation Solution
A positive electrode active material with a high nickel content (90 mol% or greater) is doped with metal elements like Al, Ti, Zr, W, or Nb, achieving a zeta potential of 30 mV or greater, which enhances dispersibility and prevents slurry gelation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content is increased to achieve high capacity, then battery capacity is improved, but slurry gelation occurs due to particle aggregation
Solution Approach 1:
A surface-modified layer comprising metal elements (Al, Ti, Zr, W, Mo, or Nb) is introduced as an intermediary between high-nickel particles. This surface modification creates a protective barrier that prevents direct particle-to-particle contact and reduces Van der Waals attraction, thereby preventing gelation while maintaining high nickel content (90 mol% or greater) for high capacity.
Solution Approach 2:
The zeta potential of particles is modified through surface doping with metal elements, changing the electrical charge characteristics of particle surfaces. This parameter change increases electrostatic repulsion between particles, counteracting the attractive Van der Waals forces that cause aggregation, thus maintaining slurry stability despite high nickel content.
2Manufacturing precision
If particle aggregation is prevented to maintain slurry uniformity, then electrode quality is improved, but dispersibility of high-nickel particles becomes more difficult to achieve
Solution Approach 1:
Metal element doping acts as a surface intermediary that modifies particle properties. The doped surface layer (Al, Ti, Zr, W, Mo, or Nb) provides steric and electrostatic barriers that prevent aggregation, enabling high-nickel particles to disperse uniformly in slurry without requiring complex processing conditions.
Solution Approach 2:
Surface charge parameters (zeta potential) are changed through metal element doping, transforming the interfacial properties of high-nickel particles. This parameter modification enhances electrostatic repulsion, making particle dispersion achievable under standard slurry preparation conditions without special equipment or procedures.
3Reliability
If metal element doping is applied to improve dispersibility, then zeta potential increases to 30 mV or greater, but material complexity increases
Solution Approach 1:
Metal element doping is applied locally at the particle surface rather than uniformly throughout the bulk material. This localized modification (surface doping) achieves the desired zeta potential increase and dispersibility improvement without requiring complex bulk material synthesis, thereby limiting the increase in overall material complexity.
Solution Approach 2:
A composite structure is created with a high-nickel core (90 mol% or greater) and a metal element surface layer (Al, Ti, Zr, W, Mo, or Nb). This composite approach combines the high capacity advantage of high-nickel materials with the dispersibility benefits of metal element doping, achieving multiple functions through a structured material design rather than complex compositions.
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 capacity and lifespan of lithium secondary batteries by maintaining structural stability and preventing slurry gelation, while reducing cobalt usage and lowering viscosity.
Implementation Method 1
the positive electrode active material has an absolute value of zeta potential measured at room temperature is 30 mV or greater
Implementation Method 2
exhibiting a zeta potential of 30 mV or greater, so that it is possible to form a high repulsive force between particles
Implementation Method 3
particle aggregation may occur in the electrode slurry due to Van der Waals force acting between the active materials or between the active material and the conductive material and/or the binder
Data Source
Figure 1
AI summary
The present invention provides a positive electrode active material, and a positive electrode, a positive electrode slurry, and a lithium secondary battery including the positive electrode active material, wherein the positive electrode active material includes a lithium nickel-based oxide including nickel, cobalt, and manganese and having a nickel content of 90 mol% or greater among metals excluding lithium, and a metal element M1 doped on the lithium nickel-based oxide, wherein the metal element M1 is one or more selected from the group consisting of Al, Ti, Zr, W, Mo, and Nb, and wherein the positive electrode active material has an absolute value of zeta potential measured at room temperature is 30 mV or greater.