Lithium Manganese Phosphate Cathode Cladding for Rate and Cycle Life

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Solution Overview

Problem

Lithium manganese phosphate secondary batteries exhibit poor rate performance and cycling performance, which is a limitation in various energy storage and power applications.

Innovation Solution

A core-shell structured lithium manganese phosphate positive electrode active material is developed, where the inner core is doped with elements like Zn, Al, and Na, and coated with a pyrophosphate and carbon cladding layer, along with a non-aqueous electrolyte solution containing specific additives to enhance lithium ion conductivity and inhibit manganese ion dissolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium manganese phosphate is used as positive electrode active material, then safety and cycle life are improved, but rate performance deteriorates

Engineering Contradiction:

Improvecycle lifeVSAvoidrate performance

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent applies a nested structure with multiple cladding layers (first cladding layer containing pyrophosphate and phosphate, second cladding layer containing carbon) surrounding the inner core of lithium manganese phosphate. This nested multi-layer cladding structure simultaneously protects the material for long cycle life while providing conductive pathways for high rate performance

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent creates a composite material system combining lithium manganese phosphate inner core with multiple cladding layers of different compositions (pyrophosphate, phosphate, and carbon). This composite structure integrates the advantages of each material: structural stability from the inner core, protective properties from the pyrophosphate and phosphate layers, and electrical conductivity from the carbon layer, achieving both long cycle life and high rate performance

Inventive Principle:

Principle #40Composite materials

2Reliability

If lithium manganese phosphate is used as positive electrode active material, then safety is improved, but rate performance deteriorates

Engineering Contradiction:

ImprovesafetyVSAvoidrate performance

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The nested multi-layer cladding structure allows the inner core to maintain its safety properties while the outer layers provide additional protective functions and conductive pathways, enabling both high safety and high rate performance simultaneously

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Different regions of the positive electrode active material are given different properties: the inner core provides structural stability and safety, the first cladding layer provides chemical stability and protection, and the second cladding layer provides electrical conductivity. This local differentiation of material properties allows the overall system to achieve both high safety and high rate performance

Inventive Principle:

Principle #3Local quality

3Speed

If cladding or doping is applied to improve rate performance, then rate performance is improved, but manufacturing complexity increases

Engineering Contradiction:

Improverate performanceVSAvoidmanufacturing complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The nested multi-layer cladding structure, while complex in design, can be manufactured through integrated processing steps that combine multiple functions into unified manufacturing operations, making the complexity manageable and scalable for production

Inventive Principle:

Principle #7Nested doll (Nesting)

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 solution significantly improves the rate performance, cycling performance, and high temperature stability of lithium manganese phosphate secondary batteries by reducing manganese dissolution and enhancing lithium ion migration, leading to better capacity utilization and safety.

Implementation Method 1

inhibit manganese ion dissolution

Methodology Applied

Scientific EffectDissolution inhibition:

Implementation Method 2

the second cladding layer includes carbon

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

enhancing lithium ion migration

Methodology Applied

Scientific EffectIon migration: Diffusion

Data Source

PatentUS12183917B2Secondary battery comprising positive electrode plate and non-aqueous electrolyte solution

Publication Date: 2024.12.31 CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

AI summary

Provided are a secondary battery, a battery module, a battery pack and an electrical apparatus. The secondary battery includes a positive electrode plate and a non-aqueous electrolyte solution. A positive electrode active material includes an inner core and a shell cladding the inner core. The inner core includes Li1+xMn1−yAyP1−zRzO4. The shell includes a first cladding layer cladding the inner core and a second cladding layer cladding the first cladding layer. The first cladding layer includes pyrophosphate MP2O7 and phosphate XPO4. The second cladding layer includes carbon. The non-aqueous electrolyte solution includes a first additive. The first additive includes one or more compounds in a group consisting of a compound shown in Formula 1, a compound shown in Formula 2 and a compound shown in Formula 3. The rate performance, cycling performance and high temperature stability of a lithium manganese phosphate secondary battery are increased.