Lithium Battery Binder Reducing Electrode Resistance

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Solution Overview

Problem

Lithium secondary batteries face increased resistance due to binders, particularly SBR, which limits their capacity and efficiency during fast charging and discharging.

Innovation Solution

A composite electrode binder system comprising a cellulose-based graft polymer with an ion-hopping site and a polyacrylate-based polymer with an anionic group, enhancing ionic conductivity and cohesive strength through non-covalent interactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If SBR/CMC heterogenous binder is used in carbon-based negative electrodes, then adhesion strength and slurry viscosity control are improved, but electrode resistance increases significantly

Engineering Contradiction:

Improveadhesion strengthVSAvoidelectrode resistance

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite binder system combining carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) in specific weight ratios (CMC: 1-10 wt%, SBR: 0.1-5 wt%). This composite approach leverages the adhesive properties of SBR while using CMC as a thickener and binder, achieving both strong adhesion and reduced resistance compared to traditional SBR/CMC heterogenous binders. The composite structure allows optimization of both binding strength and electrical conductivity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the weight ratios of CMC and SBR components, as well as controlling slurry viscosity parameters during preparation. By adjusting these parameters within specific ranges, the invention achieves the optimal balance between adhesion strength and electrode resistance, reducing the harmful resistive effects while maintaining necessary mechanical bonding.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If binder components are increased to improve adhesion, then cohesive strength is improved, but internal electrode resistance increases

Engineering Contradiction:

Improvecohesive strengthVSAvoidinternal electrode resistance

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent carefully controls the concentration and weight ratios of binder components (CMC: 1-10 wt%, SBR: 0.1-5 wt%) to achieve optimal cohesive strength. By optimizing these parameters, the invention ensures sufficient binding stability while minimizing the resistive impact of binder materials on electrode performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies binder materials with different local functions: CMC provides thickening and structural stability, while SBR provides adhesive bonding. This localized functional distribution allows each component to contribute to cohesive strength without unnecessarily increasing overall electrode resistance, as each material is used in its optimal concentration range.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If traditional binder materials are used, then ease of manufacture is improved, but fast charge/discharge behavior is limited due to resistance

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidfast charge/discharge rate

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent employs a composite CMC-SBR binder system that maintains ease of manufacture through conventional slurry preparation methods while significantly improving fast charge/discharge performance. The composite structure reduces electrode resistance, enabling higher current rates and faster charging/discharging without complicating the manufacturing process.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

By optimizing slurry viscosity and binder composition parameters, the patent achieves improved fast charge/discharge behavior while maintaining manufacturing simplicity. The controlled parameter ranges allow for straightforward production processes that yield electrodes with reduced resistance and enhanced rate capability.

Inventive Principle:

Principle #35Parameter changes

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 binder system reduces electrode resistance, improving the electrochemical rate capability and adhesion strength, thereby enhancing the fast charge/discharge behavior of lithium secondary batteries.

Implementation Method 1

a cellulose-based graft polymer grafted with a compound having an ion-hopping site

Methodology Applied

Scientific EffectIon-hopping:

Implementation Method 2

a polyacrylate-based polymer that has an anionic group by exchange with a cation

Methodology Applied

Scientific EffectNon-covalent interactions: Van der Waals Force

Data Source

PatentUS20230046215A1Electrode binder for lithium secondary battery, and electrode and lithium secondary battery including the same

Publication Date: 2023.02.16 SAMSUNG SDI CO LTD

AI summary

An electrode binder for a lithium secondary battery, and an electrode and a lithium secondary battery, including the electrode binder. The electrode binder includes: a cellulose-based graft copolymer grafted with a compound having an ion-hopping site; and a polyacrylate-based polymer having an anionic group via an exchange with a cation. By including the electrode binder in at least one of the positive electrode and the negative electrode, it is possible to provide a lithium secondary battery capable of enhancing fast charging/discharging behavior efficiency of the electrode by reducing electrode resistance generated inside the electrode during charging/discharging.