Cathode Active Material Mixing Crystal Types for Stable High-Ni Batteries
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Solution Overview
Problem
Lithium nickel cobalt manganese ternary material-based batteries face challenges in balancing energy density, cycling performance, high-temperature performance, and furnace temperature safety performance due to increased nickel content leading to surface activity, Li+/Ni2+ mixing, and structural instability.
Innovation Solution
A positive electrode active material composed of a mixture of single crystal and polycrystalline particles, with specific ratios of Al and optionally Zr, to enhance structural stability and inhibit Li+/Ni2+ mixing, thereby improving cycling and high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the content of nickel is increased to improve energy density, then the energy density is improved, but the cycling performance, high-temperature performance, and furnace temperature safety performance deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the surface region has different composition and properties from the bulk. The surface is modified with specific elements to reduce activity and prevent side reactions, while the bulk maintains high nickel content for energy density. This resolves the contradiction by localizing the functional properties to different regions of the material.
Solution Approach 2:
The patent uses composite materials by combining multiple elements (Ni, Co, Mn, and surface-modifying elements) to create a multi-component system. The composite structure allows the bulk to provide high capacity through nickel while the surface components provide stability and safety, thus resolving the contradiction between energy density and reliability.
2Use of energy by moving object
If the content of nickel is increased to improve energy density, then the energy density is improved, but the high-temperature performance deteriorates
Solution Approach 1:
The surface modification creates a localized region with enhanced thermal stability that protects the high-nickel bulk from thermal degradation. This local quality differentiation allows the material to maintain high energy density while exhibiting improved high-temperature performance.
Solution Approach 2:
The surface modification acts as a protective layer that prevents harmful side reactions before they can occur during high-temperature operation. This beforehand cushioning protects the bulk material from thermal runaway and degradation, resolving the contradiction between energy density and high-temperature performance.
3Use of energy by moving object
If the content of nickel is increased to improve energy density, then the energy density is improved, but the furnace temperature safety performance deteriorates
Solution Approach 1:
The surface modification creates a localized protective barrier that prevents harmful reactions at the particle surface during high-temperature processing. This local quality differentiation allows the bulk to maintain high nickel content for energy density while the surface provides safety during furnace processing.
Solution Approach 2:
The surface-modified layer acts as an intermediary between the high-nickel bulk material and the external environment (electrolyte, oxygen). This intermediary layer prevents direct harmful interactions while allowing the bulk to maintain its high energy density properties.
4Quantity of substance
If the content of nickel is increased, then the surface activity increases leading to more side reactions, but the structural stability decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the surface region has different composition and properties from the bulk. The surface is modified with specific elements to reduce activity and prevent side reactions, while the bulk maintains high nickel content for energy density. This resolves the contradiction by localizing the functional properties to different regions of the material.
Data Source
AI summary
Disclosed are a positive electrode active material, a positive electrode plate and a battery including the positive electrode active material. The positive electrode active material includes a first particle and a second particle; the first particle includes a single crystal particle, the second particle includes a polycrystalline particle; the first particle includes element Al, the second particle includes element Al, and a weight content of element Al in the first particle Can and a weight content of element Al in the second particle CAl2 satisfy 0.4≤CAl2/CAl1≤4. The battery of the present disclosure can take into account energy density, cycling performance, high temperature performance, and furnace temperature safety performance.