Overlithiated Cathode Material with Olivine Coating for Structural Stability

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Solution Overview

Problem

Lithium metal oxides used as cathode active materials in lithium batteries are expensive and have limited electric capacity, with high charge voltages leading to structural instability and rapid capacity decrease due to lithium removal.

Innovation Solution

A composite cathode active material comprising an overlithiated metal oxide with a layered structure, an olivine structure, and nitrogen-doped or nitride/carbide inorganic materials, which improves thermal stability and high C-rate characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a relatively high charge voltage is applied to lithium metal oxide, then lithium may be removed from the lithium metal oxide, but the lithium metal oxide becomes structurally unstable and electric capacity rapidly decreases

Engineering Contradiction:

Improvecharge voltageVSAvoidstructural stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent creates a composite cathode active material consisting of overlithiated metal oxide particles (providing high capacity) coated with an olivine structure material layer (providing structural stability). This composite structure allows the material to withstand high charge voltages while maintaining structural integrity, resolving the contradiction between achieving high voltage operation and maintaining structural stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The olivine structure material layer is applied beforehand to the overlithiated metal oxide particles to provide protective cushioning. This coating layer prevents structural degradation before it occurs during high voltage charging, allowing the core material to maintain stability even when subjected to high charge voltages that would otherwise cause lithium removal and structural collapse.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Quantity of substance

If overlithiated metal oxide is used to increase electric capacity, then capacity is improved, but thermal stability deteriorates

Engineering Contradiction:

Improveelectric capacityVSAvoidthermal stability

Core Design Contradiction:

Quantity of substanceVSTemperature

Solution Approach 1:

The patent combines overlithiated metal oxide (high capacity but low thermal stability) with olivine structure material (moderate capacity but high thermal stability) in a composite structure. The olivine coating layer acts as a thermal buffer, allowing the core high-capacity material to function while the outer layer provides thermal stability, thus resolving the contradiction between capacity and thermal stability.

Inventive Principle:

Principle #40Composite materials

3Productivity

If lithium metal oxide is used as cathode active material, then battery can operate, but the material is relatively expensive and has limited electric capacity

Engineering Contradiction:

Improveelectric capacityVSAvoidcost effectiveness

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent modifies the stoichiometric composition by creating overlithiated metal oxide (with lithium content exceeding the stoichiometric ratio) to increase electric capacity beyond the limitations of conventional lithium metal oxides. This compositional parameter change allows the material to provide higher capacity while the olivine coating maintains structural integrity, improving both capacity and cost-effectiveness.

Inventive Principle:

Principle #35Parameter changes

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 composite material enhances thermal stability and high C-rate performance, maintaining battery capacity and reducing the risk of structural instability associated with lithium removal.

Implementation Method 1

improves thermal stability and high C-rate characteristics

Methodology Applied

Scientific EffectThermal stability:

Implementation Method 2

nitrogen atoms doped in the material having an olivine structure

Methodology Applied

Scientific EffectDoping: Dopants

Implementation Method 3

maintaining battery capacity and reducing the risk of structural instability associated with lithium removal

Methodology Applied

Scientific EffectStructural stability:

Data Source

PatentUS10305100B2Composite cathode active material, and cathode and lithium battery including the material

Publication Date: 2019.05.28 SAMSUNG SDI CO LTD

AI summary

A composite cathode active material including an overlithiated metal oxide having a layered structure, a material having an olivine structure, and one or more of: an inorganic material, and nitrogen atoms doped in the material having an olivine structure. The inorganic material includes a nitride or carbide of a non-transition metal. The composite cathode active material may be included in a cathode, and the cathode may be included in a lithium battery.