Nickel-Based Cathode Binder Ratio for Battery Safety

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Solution Overview

Problem

Rechargeable lithium batteries face challenges in achieving both excellent safety and cycle life characteristics, particularly in resisting penetration and maintaining performance over cycles, due to limitations in existing nickel-based and cobalt-based positive active materials.

Innovation Solution

A positive electrode comprising a nickel-based positive active material, a binder, and a conductive material, with the binder included in a specific weight ratio of 120 to 160 parts per 100 parts of conductive material, enhancing resistance to penetration and cycle life by optimizing the weight ratio of binder and conductive material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If nickel-based positive active material is used to reduce cost and increase discharge capacity, then productivity and cost-effectiveness are improved, but safety deteriorates due to abrupt exothermic reaction at around 300°C

Engineering Contradiction:

Improvedischarge capacityVSAvoidsafety

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite positive active material with the formula Li[Ni x Co y Mn z ]O 2 where x, y, and z are specifically controlled (0.6≤x<0.8, 0.1≤y≤0.4, 0.1≤z≤0.4). This composite structure combines nickel-based materials (for high capacity) with cobalt and manganese (for thermal stability), creating a material that achieves both high discharge capacity and improved safety by suppressing abrupt exothermic reactions.

Inventive Principle:

Principle #40Composite materials

2Reliability

If cobalt-based positive active material is used to improve safety and electrode characteristics, then reliability is improved, but cost increases

Engineering Contradiction:

ImprovesafetyVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent optimizes the local composition of the positive active material by controlling the ratios of nickel, cobalt, and manganese in the formula Li[Ni x Co y Mn z ]O 2. By placing cobalt and manganese in specific proportions within the nickel-based structure, the material achieves localized thermal stability while maintaining overall high capacity and low cost characteristics.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If manganese-based positive active material is used to reduce cost and improve environmental friendliness, then ease of manufacture is improved, but capacity decreases

Engineering Contradiction:

ImprovecostVSAvoiddischarge capacity

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent merges manganese-based materials with nickel-based materials in a composite structure Li[Ni x Co y Mn z ]O 2. The manganese component provides cost-effectiveness and ease of manufacture, while the nickel component contributes high discharge capacity. The synergistic combination allows the material to achieve both economic advantages and high performance.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP2221903B1Positive electrode for rechargeable lithium battery and rechargeable lithium battery including same

Publication Date: 2015.04.01 SAMSUNG SDI CO LTD

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AI summary

A positive electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same. The positive electrode includes a nickel-based positive active material, a binder, and a conductive material, wherein the binder is included in an amount of 120 to 160 parts by weight based on 100 parts by weight of the conductive material.