Lithium Manganate Particle Morphology Control for Battery Stability

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Solution Overview

Problem

Lithium manganate particles used in non-aqueous electrolyte secondary batteries face challenges in achieving high packing density, load characteristics, and high-temperature stability, with existing methods failing to fully enhance these properties and control particle shape for improved performance.

Innovation Solution

The use of lithium manganate particles with a dodecahedral or higher-polyhedral shape, inhibited by phosphorus or aluminum compounds, which suppress the growth of specific crystal planes to improve packing and stability, and a ratio of Li to Mn and substituting metal elements optimized for reduced resistance and enhanced capacity retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium manganate particles are highly enhanced in crystallizability to obtain a crystal structure suitable for enhanced performance, then the battery capacity and charge/discharge characteristics are improved, but the particles form an octahedral shape with low packing rate, leading to deteriorated battery capacity and high-temperature characteristics

Engineering Contradiction:

Improvebattery capacity and charge/discharge characteristicsVSAvoidparticle shape (octahedral)

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent changes the crystallization parameters by controlling the calcination temperature range (900-1000°C) and atmosphere (oxygen partial pressure 0.2-1.0 atm) to obtain a specific crystal structure with high-density planes, transforming the particle morphology from octahedral to a shape with better packing properties while maintaining high crystallizability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite approach by combining lithium manganate with small amounts of lithium iron manganate (0-20 mol%) to modify the crystal structure and particle morphology, achieving both high crystallizability and improved packing density without forming octahedral shapes

Inventive Principle:

Principle #40Composite materials

2Duration of action of moving object

If the crystal lattice is expanded and contracted owing to desorption and insertion behavior of lithium ions, then charge/discharge cycles are enabled, but the crystal lattice breaks, causing deteriorated current collecting property and manganese elution

Engineering Contradiction:

Improvecharge/discharge cycle capabilityVSAvoidcrystal lattice strength

Core Design Contradiction:

Duration of action of moving objectVSStrength

Solution Approach 1:

The patent applies prior cushioning by creating a surface coating layer on the lithium manganate particles during calcination, which acts as a protective buffer to prevent crystal lattice breakage and manganese elution during repeated charge/discharge cycles, while still allowing lithium ion transport

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If cobalt-based materials (LiCoO2, LiCo1-xNixO2) are used to achieve high voltage and high capacity, then battery performance is improved, but production cost increases due to limited cobalt supply and environmental safety deteriorates

Engineering Contradiction:

Improvevoltage and capacityVSAvoidproduction cost and environmental compatibility

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive and environmentally problematic cobalt-based materials with cheaper, environmentally friendly lithium manganate, accepting some performance trade-off but achieving cost-effectiveness and environmental sustainability through optimized crystal structure and particle morphology control

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 resulting positive electrode active substance exhibits improved packing properties, load characteristics, and high-temperature stability, leading to enhanced performance and longevity of lithium-ion batteries.

Implementation Method 1

a phosphorus compound and/or an aluminum compound are used as a crystal plane growth inhibitor

Methodology Applied

Scientific EffectCrystal plane growth inhibition: Crystallisation

Implementation Method 2

the crystal lattice is expanded and contracted owing to desorption and insertion behavior of lithium ions in the crystal structure to cause change in volume of the crystal

Methodology Applied

Scientific EffectLithium ion insertion and desorption: Absorption (physical)

Data Source

PatentEP2381515B1Positive electrode active material for secondary batteries with nonaqueous electrolytic solution, process for the production of the active material, and secondary batteries with nonaqueous electrolytic solution

Publication Date: 2019.05.01 TODA KOGYO CORP

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AI summary

The present invention relates to positive electrode active substance particles for lithium ion batteries, comprising lithium manganate particles comprising Li and Mn as main components and having a cubic spinel structure (Fd-3m), wherein primary particles of the positive electrode active substance have a dodecahedral or higher-polyhedral shape in which none of crystal planes equivalent to the (111) plane are located adjacent to each other, and flat crystal planes are crossed with each other to form a clear ridge, and an average primary particle diameter of the primary particles is not less than 1 µm and not more than 20 µm. The positive electrode active substance particles according to the present invention are excellent in packing property, load characteristics and high-temperature stability.