Lithium Battery Si-C Negative Electrode Irreversible Capacity

Solution Overview

Problem

Conventional lithium secondary batteries face challenges in achieving high energy density and lifetime characteristics due to the generation of highly reactive Ni+4 ions in high-nickel positive electrode active materials and the large irreversible capacity and volume change of Si-based negative electrode active materials, leading to structural collapse and reduced efficiency.

Innovation Solution

The use of a single-particle positive electrode active material with a medium-sized particle diameter and a Si-C composite as the negative electrode active material, where the irreversible capacity of the negative electrode is smaller than that of the positive electrode, thereby minimizing negative electrode volume expansion and improving lifetime characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high-nickel lithium nickel-based oxide is applied as positive electrode active material to improve capacity characteristics, then energy density is improved, but highly reactive Ni+4 ions are generated in large amount causing structural collapse and reducing lifetime characteristics

Engineering Contradiction:

Improvecapacity characteristicsVSAvoidlifetime characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent optimizes the particle diameter parameter of the positive electrode active material to D50=5.5μm to 8μm, which changes the physical parameters to reduce Ni+4 ion generation and structural collapse while maintaining high capacity characteristics

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a Si-C composite negative electrode active material that combines silicon with carbon, creating a composite structure that maintains high capacity while reducing volume expansion and improving lifetime characteristics

Inventive Principle:

Principle #40Composite materials

2Productivity

If Si-based negative electrode active material is applied to improve fast-charging performance and capacity characteristics, then fast-charging performance is improved, but large irreversible capacity and volume change accelerate deterioration and reduce lifetime characteristics

Engineering Contradiction:

Improvefast-charging performanceVSAvoidlifetime characteristics

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent uses a Si-C composite negative electrode active material that combines silicon with carbon, creating a composite structure that maintains high capacity while reducing volume expansion and improving lifetime characteristics

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the particle diameter parameter of the positive electrode active material to D50=5.5μm to 8μm, which changes the physical parameters to reduce Ni+4 ion generation and structural collapse while maintaining high capacity characteristics

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250210724A1Lithium Secondary Battery

Publication Date: 2025.06.26 LG ENERGY SOLUTION LTD

AI summary

A lithium secondary battery having high energy density and excellent lifetime characteristics includes: (1) a positive electrode containing a positive electrode active material in a single particle form having a D50 of 5.5 μm to 8 μm; (2) a negative electrode containing a first negative electrode active material having a Si—C composite; and (3) an electrolyte. The irreversible capacity per unit area of the negative electrode is smaller than an irreversible capacity per unit area of the positive electrode.