LMFP-LFP Composite Cathode for Higher Density and Safer Batteries

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Solution Overview

Problem

Lithium-ion batteries, particularly lithium iron phosphate (LFP) batteries, face limitations in energy density and safety performance compared to ternary batteries, necessitating improvements in compaction density and operating voltage to enhance energy storage capacity and safety.

Innovation Solution

A composite positive-electrode material is developed by compounding lithium manganese iron phosphate (LMFP) with lithium iron phosphate (LFP) in various particle size ranges, allowing for adjustable operating voltage and improved energy density and safety performance through enhanced compaction density and cycling performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If LFP material is used to improve safety performance, then safety is improved, but energy density is limited due to lower operating voltage

Engineering Contradiction:

Improvesafety performanceVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies composite materials by combining LMFP and LFP in specific ratios within the positive electrode. The LMFP component provides higher operating voltage (4.1V) to improve energy density, while the LFP component maintains safety performance. This composite structure resolves the contradiction by integrating the advantages of both materials rather than using either alone.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical composition parameters of the positive electrode material by adjusting the ratio of LMFP to LFP. By controlling the content of each component (with LMFP at 10-90 wt% and LFP at 90-10 wt%), the operating voltage and energy density can be optimized while maintaining safety performance, thus resolving the contradiction through parameter optimization.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If compaction density of LFP material is improved to increase energy density, then energy density is improved, but compaction density is limited to below 2.65 g/cm³

Engineering Contradiction:

Improveenergy densityVSAvoidcompaction density

Core Design Contradiction:

Use of energy by moving objectVSQuantity of substance

Solution Approach 1:

The patent uses composite materials with different particle sizes and densities. The LMFP and LFP components have different physical properties that, when combined, achieve a compaction density exceeding 2.65 g/cm³. This composite approach overcomes the limitation of pure LFP material by leveraging the complementary properties of both materials.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating a heterogeneous structure where different particle size ranges of LMFP and LFP are distributed throughout the electrode. This non-uniform distribution optimizes packing efficiency and achieves higher compaction density in specific regions, thereby increasing overall energy density beyond what homogeneous LFP can achieve.

Inventive Principle:

Principle #3Local quality

3Use of energy by moving object

If ternary material is used to achieve higher energy density with operating voltage of 3.8V, then energy density is improved, but safety performance deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidsafety performance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies composite materials by combining LMFP (providing high voltage 4.1V for energy density) with LFP (providing safety performance). This composite positive electrode material achieves both high energy density and improved safety, resolving the contradiction between energy density and safety that plagues ternary materials.

Inventive Principle:

Principle #40Composite materials

4Reliability

If LMFP is used as additive in NCM battery to improve safety, then safety is improved, but the potential of LMFP as positive-electrode active material is ignored

Engineering Contradiction:

Improvesafety performanceVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent inverts the conventional approach by not using LMFP merely as a safety additive in NCM batteries, but rather as a primary active material in the positive electrode combined with LFP. This inversion fully utilizes the high voltage potential (4.1V) of LMFP for energy density while maintaining safety benefits, rather than treating it as a secondary additive.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS20250015265A1Composite positive-electrode material, method of manufacturing the same, and application of the same

Publication Date: 2025.01.09 EVE POWER CO LTD

AI summary

A composite positive-electrode material includes LMFP and LFP. The LMFP has a primary particle size in a range of 20 nm-200 nm. The LFP has a primary particle size in at least two ranges of: 100 nm-200 nm; 200 nm-350 nm; 350 nm-500 nm; and 500 nm-1000 nm. The primary particle size of the LFP is larger than the primary particle size of the LMFP.