Composite Positive Active Material for Lithium Battery Structural Stability

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Solution Overview

Problem

Lithium batteries face challenges in achieving improved lifespan and capacity characteristics, as well as reduced discharge voltage decay during repeated charging and discharging, due to instability of existing positive active materials under high-voltage conditions.

Innovation Solution

A composite positive active material is developed, comprising a combination of Li2TiO3 or Li2ZrO3 with LiMO2 and Li2MnO3, which provides structural stability and improved ion conductivity, reducing cation mixing and enhancing the battery's performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional positive active materials are used, then the battery can operate, but the structure becomes unstable during repeated charging and discharging

Engineering Contradiction:

Improvestructural stabilityVSAvoidlifespan

Core Design Contradiction:

Stability of the object's compositionVSDuration of action of stationary object

Solution Approach 1:

The patent applies composite materials by combining Li2TiO3 or Li2ZrO3 with LiMO2 and Li2MnO3 to form a composite positive active material. This composite structure provides both structural stability from the spinel phase and high capacity characteristics from the layered phase, resolving the contradiction between structural stability and lifespan.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If high-voltage conditions are applied to increase capacity, then the battery capacity improves, but the positive active material becomes unstable

Engineering Contradiction:

Improvebattery capacityVSAvoidmaterial stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The composite structure combines materials with different stability characteristics, allowing the battery to operate at high voltages (4.2V or higher) while maintaining material stability through the protective spinel phase component.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the compositional parameters by controlling the ratios of Li2TiO3/Li2ZrO3 to LiMO2/Li2MnO3 within specific ranges (0.05-0.5 and 0.5-0.95 respectively), optimizing the balance between capacity and stability at high voltages.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If single-phase materials are used, then the material structure is simple, but the ion conductivity is insufficient

Engineering Contradiction:

Improveion conductivityVSAvoidmaterial structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The composite positive active material combines spinel phase (Li2TiO3 or Li2ZrO3) and layered phase (LiMO2 and Li2MnO3) to achieve synergistic effects, where the spinel phase provides high ion conductivity and the layered phase provides high capacity, overcoming the limitations of single-phase materials.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP3279144B1Composite positive active material, positive electrode including the same, and lithium battery including the positive electrode

Publication Date: 2019.10.09 SAMSUNG ELECTRONICS CO LTD

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AI summary

A composite positive active material including a composite represented by Formula 1: Formula 1 δLi2MO3·(1-δ)[xLi2MnO3·(1-x)LidNiaCobM'cO2] wherein, in Formula 1, M is titanium (Ti) or zirconium (Zr); M' is manganese (Mn), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof; and 0<δ<0.5; 0<x<0.3; a+b+c≤1; 0<a<1; 0<b<1; 0<c<1, and 0.95≤d≤1.05.