Lithium Manganate Particles for High-Temperature Cycle Stability

Solution Overview

Problem

Lithium manganate particles used in secondary batteries suffer from poor high-temperature stability and charge/discharge cycle characteristics, leading to capacity deterioration and manganese elution, which existing methods have not adequately addressed.

Innovation Solution

Lithium manganate particles with a sulfur content of 1 to 100 ppm and an average secondary particle diameter of 1 to 15 μm, composed of Li1+xMn2-x-yYyO4+zA, where Y is Al or Mg, and A is a sintering aid with a melting point below 850°C, are produced by calcining a mixture of manganese oxide, a Y element compound, and a lithium compound at 800°C to 1050°C, resulting in improved high-temperature stability and capacity retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If lithium manganate particles are used as positive electrode active material, then high output voltage and high energy density are achieved, but charge/discharge cycle characteristics deteriorate due to crystal lattice expansion and contraction

Engineering Contradiction:

Improveoutput voltageVSAvoidcharge/discharge cycle characteristics

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the inner core maintains the original spinel structure for high capacity, while the outer shell has a modified structure with reduced Jahn-Teller distortion for improved stability. This local structural differentiation resolves the contradiction between high output and cycle stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining lithium manganate with other lithium metal oxides or lithium metal oxyhydroxides to form a composite positive electrode active material. This composite structure mitigates the crystal lattice expansion and contraction issues while maintaining high output characteristics.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium manganate particles are used as positive electrode active material, then high energy density is achieved, but high-temperature stability deteriorates due to manganese dissolution in electrolyte solution

Engineering Contradiction:

Improveenergy densityVSAvoidhigh-temperature stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the inner core maintains the original spinel structure for high capacity, while the outer shell has a modified structure with reduced Jahn-Teller distortion for improved stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining lithium manganate with other lithium metal oxides or lithium metal oxyhydroxides to form a composite positive electrode active material. This composite structure mitigates the crystal lattice expansion and contraction issues while maintaining high output characteristics.

Inventive Principle:

Principle #40Composite materials

3Power

If cobalt-based materials like LiCoO2 are used, then high voltage and high capacity are achieved, but production cost increases due to limited cobalt supply

Engineering Contradiction:

Improvevoltage and capacityVSAvoidproduction cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by modifying the chemical composition parameters of the positive electrode active material, specifically using lithium manganate-based compositions with controlled ratios of lithium, manganese, and other metal elements. This compositional parameter adjustment achieves high voltage and capacity while using abundant, low-cost materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining lithium manganate with other lithium metal oxides or lithium metal oxyhydroxides to form a composite positive electrode active material. This composite structure mitigates the crystal lattice expansion and contraction issues while maintaining high output characteristics.

Inventive Principle:

Principle #40Composite materials

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 lithium manganate particles exhibit a high-temperature cycle retention rate of not less than 92% and capacity recovery rate of not less than 95%, making them suitable for non-aqueous electrolyte secondary batteries with enhanced output and stability.

Implementation Method 1

calcining the resulting mixture at a temperature of 800°C to 1050°C

Methodology Applied

Scientific EffectCalcination: Heating

Data Source

PatentUS10056612B2Lithium manganate particles for non-aqueous electrolyte secondary battery, process for producing the same, and nonaqueous electrolyte secondary battery

Publication Date: 2018.08.21 TODA KOGYO CORP

AI summary

This invention provides lithium manganate which has a high output and is excellent in high-temperature stability. This invention relates to lithium manganate particles which are produced by mixing a lithium compound, a manganese compound, a Y compound and an A compound and then calcining the resulting mixture, and have a composition represented by the following chemical formula 1 and an average secondary particle diameter (D50) of 1 to 15 μm, in which Y is at least one element selected from the group consisting of Al and Mg; A is a sintering aid element having a melting point of not higher than 850° C.; x and y satisfy 0.03≤x≤0.15 and 0≤y≤0.20, respectively; z is in the range of 0 to 2.5 mol % based on Mn, wherein the lithium manganate particles have a sulfur content of not more than 100 ppm.Li1+xMn2-x-yYyO4zA (Chemical Formula 1)