Secondary Battery Positive Electrode Multilayer Structure

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Solution Overview

Problem

Current lithium-ion secondary batteries face challenges in achieving high charge and discharge capacity, voltage, and long-term reliability while maintaining a safe and durable design, particularly for applications requiring high energy density and extended cruising ranges with minimal weight increase.

Innovation Solution

A secondary battery design featuring a positive electrode active material with a multilayer structure, including regions with varying concentrations of nickel, cobalt, and manganese, and an impurity region to inhibit interdiffusion, combined with the use of graphene as a conductive additive to enhance conductivity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the nickel concentration is increased in the positive electrode active material, then the charge and discharge capacity is improved, but the structural stability deteriorates leading to faster deterioration

Engineering Contradiction:

Improvecharge and discharge capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating a concentration gradient of nickel within the positive electrode active material particles. The nickel concentration is higher in the inner region compared to the outer region, allowing the inner core to provide high charge/discharge capacity while the outer region maintains structural stability. This spatial variation in composition resolves the contradiction between capacity and stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining regions with different nickel concentrations within the same positive electrode active material. The multi-region structure (inner region with high nickel concentration, outer region with lower nickel concentration) creates a composite material system where each region contributes different properties - the inner region provides capacity while the outer region provides stability.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If the nickel concentration is increased to achieve high charge and discharge voltage, then the energy density is improved, but the material deterioration accelerates

Engineering Contradiction:

Improveenergy densityVSAvoidmaterial durability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements local quality by varying the nickel concentration spatially within the positive electrode active material. The inner region has high nickel concentration to provide high voltage and energy density, while the outer region has lower nickel concentration to ensure durability. This local differentiation allows simultaneous achievement of high energy density and material durability.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If a uniform high nickel concentration is used throughout the positive electrode active material, then the charge and discharge capacity is maximized, but the structural integrity deteriorates

Engineering Contradiction:

Improvecharge and discharge capacityVSAvoidstructural integrity

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a non-uniform nickel concentration distribution within the positive electrode active material particles. The inner region contains high nickel concentration for high capacity, while the outer region contains lower nickel concentration for structural integrity. This spatially differentiated composition resolves the contradiction between maximizing capacity and maintaining structural integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses segmentation by dividing the positive electrode active material into multiple regions with different nickel concentrations. The inner region and outer region are segmented with distinct compositional characteristics, allowing each segment to fulfill different functional requirements - the inner segment for capacity and the outer segment for structural integrity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20230129659A1Secondary battery, electronic device, and vehicle

Publication Date: 2023.04.27 SEMICON ENERGY LAB CO LTD

AI summary

A positive electrode active material with high charge and discharge capacity is provided. A positive electrode active material with high charge and discharge voltage is provided. A power storage device that hardly deteriorates is provided. A highly safe power storage device is provided. A novel power storage device is provided. A positive electrode active material containing lithium, a plurality of transition metals, oxygen, and an impurity element. The positive electrode active material includes a first region including a surface portion and a second region provided inward from the first region, and the concentration of a transition metal is higher in the first region than in the second region. An impurity region is included between the first region and the second region.