Conductive Agent Composite for Lithium Battery Electrodes

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Solution Overview

Problem

Conventional lithium secondary batteries face challenges in achieving high active mass density and reduced resistance in positive electrodes, particularly with Ni-based materials, which have low hardness and difficulty in forming high-density electrode plates due to their spherical shape and low hardness, limiting battery capacity.

Innovation Solution

A conductive agent/positive active material composite is developed, comprising a positive active material capable of reversible lithium intercalation, coated with a first conductive agent having a specific surface area of 200-1500 m2/g and a second conductive agent with a surface area of 100 m2/g or less, mixed and coated using mechanofusion or planetary mixing to form a conductive layer, enhancing electron conductivity and active mass density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If Ni-based positive active materials are used, then battery capacity is improved, but active mass density remains low due to spherical shape and low hardness

Engineering Contradiction:

Improvebattery capacityVSAvoidactive mass density

Core Design Contradiction:

Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The patent applies composite materials by combining Ni-based positive active material particles with conductive agent particles to form a composite structure. The conductive agent particles fill the spaces between and on the surface of the spherical Ni-based particles, creating a composite that maintains the high capacity of Ni-based materials while increasing the overall density of the active mass in the electrode plate.

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional conductive agents are used, then electrical conductivity is improved, but active mass density decreases due to volume occupation

Engineering Contradiction:

Improveelectrical conductivityVSAvoidactive mass density

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent applies local quality by concentrating the conductive agent primarily on the surface of the positive active material particles rather than uniformly distributing it throughout the electrode. This surface-localized approach ensures adequate electrical conductivity at the critical particle interfaces while minimizing the volume occupied by conductive agent in the bulk electrode structure, thereby preserving active mass density.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If spherical Ni-based particles are used, then manufacturing ease is improved, but electrode plate density cannot be increased through compression

Engineering Contradiction:

Improveparticle formationVSAvoidelectrode plate density

Core Design Contradiction:

Ease of manufactureVSVolume of stationary object

Solution Approach 1:

The patent uses the conductive agent particles as an intermediary substance that fills the void spaces between the spherical Ni-based particles and forms a matrix that enables denser packing. This intermediary material allows the electrode plate to achieve higher density under compression without requiring the Ni-based particles themselves to deform or break, maintaining manufacturing ease while increasing overall density.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 composite reduces electrode resistance and increases active mass density, improving battery capacity and cycle-life characteristics by ensuring uniform electrolyte immersion and electrochemical reactions, thus enhancing the performance of lithium secondary batteries.

Implementation Method 1

a conductive agent on the surface of the positive active material. The conductive agent includes a first conductive agent having a specific surface area ranging from about 200 to about 1500 m2/g, and a second conductive agent having a specific surface area of about 100 m2/g or less

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a positive active material capable of reversibly intercalating/deintercalating lithium ions

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Data Source

PatentUS7838152B2Conductive agent-positive active material composite for lithium secondary battery, method of preparing the same, and positive electrode and lithium secondary battery comprising the same

Publication Date: 2010.11.23 SAMSUNG SDI CO LTD

AI summary

The present invention relates to a conductive agent/positive active material composite for a lithium secondary battery. The composite includes a positive active material capable of reversibly intercalating/deintercalating lithium ions, and a conductive agent on the surface of the positive active material. The conductive agent comprises a first conductive agent having a specific surface area ranging from about 200 to about 1500 m2/g and a second conductive agent having a specific surface area of about 100 m2/g or less.