LFP Cathode and Electrolyte Composition for Fast-Charging Cycle Life

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Solution Overview

Problem

Lithium-ion secondary batteries face challenges in achieving fast-charge performance without compromising cycle performance and safety, particularly when using lithium iron phosphate as a positive electrode material.

Innovation Solution

A secondary battery design incorporating a positive electrode plate with two lithium iron phosphate materials of varying particle sizes and a specific electrolyte solution, including a micromolecular carboxylate ester solvent, enhances fast-charge capability while maintaining low gas generation and good cycle performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If lithium iron phosphate material with small particle size is used to improve fast-charge performance, then fast-charge capability is improved, but volume expansion rate increases and cycle performance deteriorates

Engineering Contradiction:

Improvefast-charge capabilityVSAvoidcycle performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The positive electrode material is segmented into two distinct particle size ranges: fine particles (Dv50: 0.05-4 μm) for fast-charge capability and coarse particles (Dv50: 6-20 μm) for structural stability and low volume expansion. This segmentation allows each particle size to fulfill its specific function, resolving the contradiction between fast-charge performance and cycle life.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the positive electrode material layer have different particle size distributions. The fine particles predominantly occupy certain regions to enhance ionic conductivity and fast-charge capability, while coarse particles are distributed in other regions to provide structural stability and reduce volume expansion during cycling.

Inventive Principle:

Principle #3Local quality

2Productivity

If lithium iron phosphate material with small particle size is used to improve fast-charge performance, then fast-charge capability is improved, but volume expansion rate increases

Engineering Contradiction:

Improvefast-charge capabilityVSAvoidvolume expansion rate

Core Design Contradiction:

ProductivityVSVolume of moving object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The positive electrode material layer is designed as a composite system combining two types of lithium iron phosphate particles with different size characteristics. This composite structure leverages the advantages of both fine particles (high surface area for fast ion transport) and coarse particles (structural integrity and low volume expansion), achieving both fast-charge capability and low volume expansion rate.

Inventive Principle:

Principle #40Composite materials

3Productivity

If conventional electrolyte solvents are used, then manufacturing simplicity is maintained, but fast-charge performance is insufficient

Engineering Contradiction:

Improvefast-charge performanceVSAvoidelectrolyte formulation complexity

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The electrolyte solvent composition is optimized by selecting specific micromolecular carboxylate esters (methyl acetate, ethyl acetate, propyl acetate, or butyl acetate) and controlling their content within 20-80 wt%. This parameter optimization enhances ionic conductivity and fast-charge performance while maintaining relatively simple manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electrolyte solution is formulated as a composite system combining micromolecular carboxylate ester solvents with lithium salt (0.5-2.0 mol/L). This composite electrolyte formulation improves fast-charge capability through enhanced ionic conductivity while maintaining practical manufacturability.

Inventive Principle:

Principle #40Composite materials

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 battery achieves improved fast-charge performance, reduced gas generation, and enhanced cycle life, ensuring safety and reliability in lithium-ion secondary batteries.

Implementation Method 1

The electrolyte solution includes a solvent, and the solvent includes a first solvent that is at least one selected from compounds represented by Formula I

Methodology Applied

Scientific EffectIon transport: Electrolysis

Implementation Method 2

The positive electrode material layer includes a first lithium iron phosphate material and a second lithium iron phosphate material

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentUS20250316766A1Secondary battery and electrical device containing same

Publication Date: 2025.10.09 CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

AI summary

A secondary battery, including a positive electrode plate and an electrolyte solution are disclosed. The positive electrode plate includes a current collector and a positive electrode material layer disposed on at least one side of the current collector. The positive electrode material layer includes a first lithium iron phosphate material and a second lithium iron phosphate material. Dv50 of the second lithium iron phosphate material is greater than Dv50 of the first lithium iron phosphate material. The Dv50 of the first lithium iron phosphate material is 0.05 μm to 6 μm. The electrolyte solution includes a solvent. The solvent includes a first solvent that is at least one selected from compounds represented by Formula I, where R1 and R2 each are independently selected from a C1 to C6 alkyl or a C1 to C6 haloalkyl. The secondary battery of this application exhibits good balanced overall performance.