Rock Salt Cathode Composition With Trace Doping for Higher Battery Capacity

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Solution Overview

Problem

Existing positive electrode active materials for lithium ion secondary batteries, such as those disclosed in PTL 1, have insufficient capacity improvement effects, leaving room for further enhancement.

Innovation Solution

A positive electrode active material containing a lithium metal composite oxide with a rock salt structure belonging to the space group Fm-3m, incorporating a trace amount of element A1 (e.g., Fe, Ca, Cr, Na, Al, Si, Mg, Cu, Zn, Pb, Sb, W) within a specific concentration range (10 ppm to 1000 ppm by mass) and a lattice constant a between 4.09 Å and 4.16 Å.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If cobalt atoms are replaced with nickel atoms to increase capacity, then the capacity of the lithium ion secondary battery is improved, but the structural stability and safety deteriorate due to the high reactivity and cost of nickel

Engineering Contradiction:

Improvebattery capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the compositional parameters by introducing a specific element A1 at precisely controlled trace concentrations (10-1000 ppm) within the lithium metal composite oxide. This trace doping approach modifies the crystal lattice parameters and electronic structure to enhance capacity while maintaining stability, resolving the contradiction between capacity improvement and structural reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by combining lithium metal oxide with trace amounts of element A1 (selected from Fe, Ca, Cr, Na, Al, Si, Mg, Cu, Zn, Pb, Sb, or W). This composite approach leverages the beneficial properties of the base lithium metal oxide while the trace element A1 provides structural stabilization, achieving both high capacity and reliability

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If Li-rich lithium metal composite oxides are used to achieve high energy density, then the energy density is improved, but the manufacturing precision and composition control become more difficult

Engineering Contradiction:

Improveenergy densityVSAvoidcomposition control

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent establishes specific parameter ranges for the composition (Li1+xMn1−xO2 with element A1 at 10-1000 ppm) and lattice constant (a = 4.09-4.16 Å). These defined parameters provide clear manufacturing targets that balance high energy density with achievable composition control, making the material synthesis more precise and reproducible

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses X-ray diffraction measurement of the lattice constant a as a non-destructive characterization method to verify composition and structure. This substitution of direct compositional analysis with structural characterization simplifies quality control and enables easier manufacturing precision verification

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This configuration significantly improves the capacity of the secondary battery, achieving high energy density, with the trace amount of element A1 facilitating electron tunneling and stabilizing the crystal structure.

Implementation Method 1

the trace amount of element A1 facilitating electron tunneling

Methodology Applied

Scientific EffectElectron tunneling:

Implementation Method 2

having a crystal structure based on a rock salt structure belonging to the space group Fm-3m

Methodology Applied

Scientific EffectCrystal structure stabilization:

Data Source

PatentUS20250062333A1Positive electrode active material for secondary batteries, and secondary battery

Publication Date: 2025.02.20 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A positive electrode active material for a secondary battery contains a lithium metal composite oxide having a crystal structure based on a rock salt structure belonging to the space group Fm-3m. The lithium metal composite oxide contains at least one element A1 selected from the group consisting of Fe, Ca, Cr, Na, Al, Si, Mg, Cu, Zn, Pb, Sb, and W. The content of the element A1 in the lithium metal composite oxide is 10 ppm by mass or more and 1000 ppm by mass or less with respect to the total amount of the lithium metal composite oxide. A lattice constant a, which indicates a length in an a-axis direction of a crystal lattice of the lithium metal composite oxide is 4.09 Å or more and 4.16 Å or less.