Layered Positive Electrode Composition for Battery Capacity and Output

Solution Overview

Problem

Conventional positive electrodes for secondary batteries, such as lithium ion batteries, struggle to achieve both high capacity and output characteristics simultaneously.

Innovation Solution

A positive electrode configuration that includes a first lithium composite oxide with a Li/Me ratio of 0.90 to 0.97 and a second lithium composite oxide with a Li/Me ratio of 1.10 to 1.20, both having layered structures. The crystallite size of the (104) plane of the first lithium composite oxide is 400 Å to 600 Å, while the second lithium composite oxide has a larger crystallite size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a lithium composite oxide with Li/Me ratio of one or less and crystallite size of 180 nm or more is used, then output characteristic is improved, but capacity characteristic deteriorates

Engineering Contradiction:

Improveoutput characteristicVSAvoidcapacity characteristic

Core Design Contradiction:

PowerVSQuantity of substance

Solution Approach 1:

The positive electrode active material layer is segmented into two distinct lithium composite oxide components with different Li/Me ratios and crystallite sizes. The first lithium composite oxide (Li/Me = 0.90-0.97, crystallite size 400-600 Å) provides high output characteristic, while the second lithium composite oxide (Li/Me = 1.10-1.20, larger crystallite size) provides high capacity characteristic. This segmentation allows both contradictory requirements to be satisfied simultaneously by distributing different functions to different components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the positive electrode active material layer have different local qualities: the first lithium composite oxide with smaller crystallite size (400-600 Å) and lower Li/Me ratio (0.90-0.97) is optimized for output characteristic in specific locations, while the second lithium composite oxide with larger crystallite size and higher Li/Me ratio (1.10-1.20) is optimized for capacity characteristic in other locations. This local quality differentiation resolves the contradiction between output and capacity characteristics.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If a lithium composite oxide with Li/Me ratio exceeding one is used, then capacity characteristic is improved, but output characteristic deteriorates

Engineering Contradiction:

Improvecapacity characteristicVSAvoidoutput characteristic

Core Design Contradiction:

Quantity of substanceVSPower

Solution Approach 1:

The positive electrode active material layer is segmented into two distinct lithium composite oxide components with different Li/Me ratios and crystallite sizes. The first lithium composite oxide (Li/Me = 0.90-0.97, crystallite size 400-600 Å) provides high output characteristic, while the second lithium composite oxide (Li/Me = 1.10-1.20, larger crystallite size) provides high capacity characteristic. This segmentation allows both contradictory requirements to be satisfied simultaneously by distributing different functions to different components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the positive electrode active material layer have different local qualities: the first lithium composite oxide with smaller crystallite size (400-600 Å) and lower Li/Me ratio (0.90-0.97) is optimized for output characteristic in specific locations, while the second lithium composite oxide with larger crystallite size and higher Li/Me ratio (1.10-1.20) is optimized for capacity characteristic in other locations. This local quality differentiation resolves the contradiction between output and capacity characteristics.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250029995A1Positive electrode and secondary battery using the same

Publication Date: 2025.01.23 PRIME PLANET ENERGY & SOLUTIONS INC

AI summary

A positive electrode disclosed here includes: a positive electrode current collector; and a positive electrode active material layer supported by the positive electrode current collector. The positive electrode active material layer includes a first lithium composite oxide having a layered structure and a second lithium composite oxide having a layered structure. In the first lithium composite oxide, a mole ratio of Li to a metal other than Li is 0.90 to 0.97. In the second lithium composite oxide, a mole ratio of Li to a metal other than Li is 1.10 to 1.20. A crystallite size of a (104) plane of the first lithium composite oxide is 400 Å to 600 Å. A crystallite size of a (104) plane of the second lithium composite oxide is larger than the crystallite size of the (104) plane of the first lithium composite oxide.