Cathode Active Material Stabilization via Phosphorus Bonding

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Solution Overview

Problem

Lithium manganese composite oxides used in lithium secondary batteries for electric vehicles suffer from manganese release at high temperatures, leading to battery property deterioration and low capacity per unit weight, necessitating additional costly processes for stabilization.

Innovation Solution

A cathode active material with a specific composition, including a transition metal layer with lithium, phosphorus, and elements like nickel, manganese, and cobalt, stabilized through strong bonding and controlled oxidation number, enhancing cycle and storage properties without additional processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium manganese composite oxide is used as cathode material, then cost is reduced and safety is improved, but manganese is released into electrolyte at high temperature causing battery property deterioration

Engineering Contradiction:

Improvebattery safetyVSAvoidmanganese stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses a composite cathode material consisting of lithium manganese composite oxide combined with lithium nickel composite oxide or lithium cobalt composite oxide. This composite structure allows the battery to benefit from the cost-effectiveness and safety of lithium manganese oxide while the lithium nickel or cobalt components provide structural stability that prevents manganese release at high temperatures, thus resolving the contradiction between safety improvement and compositional stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the composition parameters by controlling the molar ratios of lithium, manganese, nickel, and cobalt in the composite cathode material. By adjusting these compositional parameters, the material achieves both the safety benefits of high manganese content and the stability needed to prevent manganese dissolution, effectively resolving the contradiction through parameter optimization.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If lithium manganese composite oxide is used, then capacity per unit weight is reduced, but cost is improved

Engineering Contradiction:

Improvecapacity per unit weightVSAvoidcost effectiveness

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent creates a composite cathode material that combines lithium manganese oxide with lithium nickel oxide or lithium cobalt oxide. This composite approach allows the battery to achieve higher capacity per unit weight by incorporating materials with superior capacity characteristics, while maintaining cost effectiveness through the use of manganese-based components, thus resolving the contradiction between capacity and cost.

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If layered mixed metal oxides are used to solve stability issues, then stability is improved, but manufacturing complexity increases due to additional surface treatment processes

Engineering Contradiction:

Improvecathode stabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges the cathode active material composition and stabilization function into a single integrated composite material system. Instead of requiring separate surface treatment processes, the stability is achieved through the intrinsic composite structure of lithium manganese oxide combined with lithium nickel or cobalt oxide, eliminating the need for additional manufacturing steps and reducing process complexity while maintaining stability.

Inventive Principle:

Principle #5Merging (Combining)

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 cathode active material significantly improves battery lifespan and storage properties, reducing capacity deterioration and maintaining performance, making it suitable for long-term use in electric vehicles.

Implementation Method 1

The cathode active material according to the present invention exhibits improved cycle properties and storage properties of an active material, through stabilization of crystal structure, based on the strong bonding force of P contained in the element composition

Methodology Applied

Scientific EffectStrong bonding force: Chemical Bonding

Implementation Method 2

Methodology Applied

Scientific EffectOxidation number variation: Redox Reactions

Data Source

PatentEP2565967B1Cathode active material for secondary battery

Publication Date: 2017.11.01 LG CHEM LTD

Figure 1

AI summary

Disclosed is a cathode active material for secondary batteries comprising, a compound having a transition metal layer containing lithium as at least one compound selected from the following Formula 1: Li(Li3x±yM1-yPx)O2+z (1) wherein M is an element stable for a six-coordination structure, which is at least one selected from transition metals that belong to the first and second period elements; 0<x<0.1; 0<y<0.3; -4x<z≤4x; and 3x>y is satisfied in a case of 3x-y.