Mixed Cathode Material for Lithium Battery Stability

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Solution Overview

Problem

Lithium manganese composite oxide used in lithium secondary batteries for electric vehicles faces challenges such as manganese elution at high temperatures, stability issues, and limited capacity per unit battery weight, which affect battery life and power characteristics, especially under severe conditions and low temperatures.

Innovation Solution

A cathode active material is developed by mixing lithium manganese oxide with at least two types of lithium nickel-manganese-cobalt composite oxides that differ in particle diameter, maintaining energy density while enhancing stability, life, and low-temperature performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium manganese composite oxide is used as cathode active material, then cost is reduced and stability is improved, but manganese is eluted at high temperature and battery life is deteriorated

Engineering Contradiction:

ImprovestabilityVSAvoidbattery life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent uses a composite material system consisting of lithium manganese oxide combined with lithium nickel-manganese-cobalt composite oxides having different particle diameters. This composite structure prevents manganese elution while maintaining the stability advantages of lithium manganese oxide, thereby extending battery life without sacrificing reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by using lithium nickel-manganese-cobalt composite oxides with different particle diameters (small particle diameter and large particle diameter) in specific proportions. The small particles provide stability while the large particles prevent elution, creating localized functional zones within the composite material that collectively extend battery life.

Inventive Principle:

Principle #3Local quality

2Reliability

If lithium manganese composite oxide is used as cathode active material, then cost is reduced and stability is improved, but capacity per unit battery weight is limited

Engineering Contradiction:

ImprovestabilityVSAvoidcapacity per unit battery weight

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent creates a composite material system where lithium manganese oxide is combined with lithium nickel-manganese-cobalt composite oxides in specific proportions (70:30 to 95:5 by weight). This composite structure maintains the stability and cost advantages of lithium manganese oxide while the lithium nickel-manganese-cobalt components contribute additional capacity, thereby increasing capacity per unit battery weight.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the compositional parameters by controlling the weight ratios of different components and their particle diameter distributions. By optimizing these parameters, the patent achieves a balance between maintaining stability and increasing capacity per unit battery weight.

Inventive Principle:

Principle #35Parameter changes

3Power

If conventional cathode materials are used, then power characteristics are sufficient, but battery life and stability under severe conditions are inadequate

Engineering Contradiction:

Improvepower characteristicsVSAvoidbattery life

Core Design Contradiction:

PowerVSDuration of action of stationary object

Solution Approach 1:

The patent uses a composite material system where lithium manganese oxide provides stability and lithium nickel-manganese-cobalt composite oxides provide power characteristics. The synergistic combination maintains excellent power characteristics while significantly extending battery life and stability under severe conditions.

Inventive Principle:

Principle #40Composite materials

4Ease of manufacture

If single-type lithium nickel-manganese-cobalt composite oxide is used, then manufacturing is simplified, but battery life and stability are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidbattery life

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent employs a composite material system combining lithium manganese oxide with lithium nickel-manganese-cobalt composite oxides. This composite structure achieves superior battery life and stability while maintaining relatively simple manufacturing processes through controlled mixing and sintering.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by incorporating lithium nickel-manganese-cobalt composite oxides with different particle diameters in specific proportions. This creates localized functional zones that collectively extend battery life while maintaining manufacturing feasibility through standardized mixing procedures.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2672552B1Positive electrode active material, and lithium secondary battery comprising same

Publication Date: 2018.01.24 LG CHEM LTD

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AI summary

Disclosed herein is a cathode active material for secondary batteries and a secondary battery including the same, the cathode active material including lithium manganese oxide (A) having a spinel crystal structure and at least two types of lithium nickel-manganese-cobalt composite oxides (B) containing Ni, Mn, and Co as transition metals, wherein the lithium nickel-manganese-cobalt composite oxides (B) are different from each other in terms of at least one selected from the group consisting of elemental composition, particle diameter, and density.