Silicon Negative Electrode with Polymer Binder for Battery Expansion

Solution Overview

Problem

Lithium secondary batteries face challenges with carbon-based negative electrodes due to low capacity and high volume expansion of silicon-based electrodes, leading to reduced cycle lifespan and delayed charge/discharge times.

Innovation Solution

A negative electrode composition including a carbon-based active material, a conductive material, and a silicon-based active material-polymer binder combination, where the polymer binder, such as polyacrylic acid or polyvinyl alcohol, is bonded to the silicon-based active material to suppress volume expansion, with specific weight percentages and preparation methods to enhance adhesion and charge/discharge efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a silicon-based material is used as a negative electrode active material to achieve higher charge/discharge capacity, then the capacity is improved, but the electrode expansion rate becomes very high and charge/discharge efficiency becomes very low

Engineering Contradiction:

Improvecharge/discharge capacityVSAvoidcharge/discharge efficiency

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a composite structure consisting of silicon-based active material particles coated with a carbon layer. This composite material combines the high capacity advantage of silicon with the structural stability and conductivity of carbon, resolving the contradiction between high capacity and low efficiency by preventing silicon expansion while maintaining electrochemical activity

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies a thin carbon coating layer on the silicon-based active material particles. This flexible shell structure accommodates the volume expansion of silicon during charging while maintaining structural integrity and preventing particle disintegration, thereby improving charge/discharge efficiency without sacrificing capacity

Inventive Principle:

Principle #30Flexible shells and thin films

2Quantity of substance

If a silicon-based material is used as a negative electrode active material to achieve higher charge/discharge capacity, then the capacity is improved, but the electrode expansion rate becomes very high

Engineering Contradiction:

Improvecharge/discharge capacityVSAvoidelectrode expansion rate

Core Design Contradiction:

Quantity of substanceVSVolume of moving object

Solution Approach 1:

The patent applies a thin carbon coating layer on the silicon-based active material particles. This flexible shell structure accommodates the volume expansion of silicon during charging while maintaining structural integrity and preventing particle disintegration, thereby improving charge/discharge efficiency without sacrificing capacity

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The carbon coating layer acts as a counterbalancing structure that constrains the expansion of silicon particles. The carbon shell provides mechanical support that counteracts the expansion force of silicon, preventing excessive volume increase while allowing the silicon to undergo its natural expansion contraction cycle

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Reliability

If carbon-based material is used as a negative electrode active material, then the charge/discharge efficiency is maintained, but the capacity is limited and not compatible with high-capacity requirements

Engineering Contradiction:

Improvecharge/discharge efficiencyVSAvoidcapacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent uses a composite structure consisting of silicon-based active material particles coated with a carbon layer. This composite material combines the high capacity advantage of silicon with the structural stability and conductivity of carbon, resolving the contradiction between high capacity and low efficiency by preventing silicon expansion while maintaining electrochemical activity

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 solution effectively suppresses volume expansion of silicon-based active materials, improving the durability and lifespan of lithium secondary batteries by maintaining high charge/discharge efficiency and capacity.

Implementation Method 1

a polymer binder bonded to a surface of the silicon-based active material, wherein the polymer binder suppresses expansion of the silicon-based active material

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

materials capable of intercalating and deintercalating, or alloying and dealloying lithium ions are used as a negative electrode and a positive electrode

Methodology Applied

Scientific EffectAlloying reaction:

Implementation Method 3

When lithium ions are intercalated and deintercalated from the positive electrode and the negative electrode, electrical energy is generated by an oxidation reaction and a reduction reaction

Methodology Applied

Scientific EffectIntercalation:

Implementation Method 4

electrical energy is generated by an oxidation reaction and a reduction reaction

Methodology Applied

Scientific EffectRedox reaction: Redox Reactions

Data Source

PatentUS11495785B2Negative electrode for secondary battery and method for producing same

Publication Date: 2022.11.08 LG ENERGY SOLUTION LTD

AI summary

A negative electrode for a secondary battery, and a method for producing the same, and more particularly, to a negative electrode for a secondary battery used for a negative electrode of a secondary battery, and a method for producing the same. A negative electrode for a secondary battery may include a carbon-based active material; a conductive material; and a silicon-based active material-polymer binder combination including a silicon-based active material, and a polymer binder for suppressing the expansion of the silicon-based active material bonded to a particle surface of the silicon-based active material.