Positive Electrode Plate Composition to Limit NiO Formation

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Solution Overview

Problem

Lithium-ion rechargeable batteries face reduced lifespan due to the generation of NiO when the nonaqueous electrolyte decomposes in high-temperature environments, which limits intercalation of lithium ions and decreases electron participation in the main reaction.

Innovation Solution

Incorporating a specific amount of lithium carbonate (0.31 wt % to 1.29 wt %) within the positive electrode active material, combined with a fibrous conductor like carbon nanotubes, to restrict NiO generation by reacting with the electrolyte and maintaining a sufficient conductive network without excessive coverage, ensuring optimal lithium ion and electron participation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the surface area of positive electrode active material contacting with nonaqueous electrolyte is increased to improve battery capacity and output, then the reactive area increases and reaction resistance decreases, but NiO2 undergoes reductive decomposition to generate NiO which accelerates battery deterioration

Engineering Contradiction:

Improvebattery capacity and outputVSAvoidbattery life

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Lithium carbonate is introduced as an intermediary substance between the positive electrode active material (NiO2) and the nonaqueous electrolyte. This intermediary reacts with the electrolyte first, forming a protective layer that prevents direct contact between the electrolyte and NiO2, thereby preventing NiO generation while maintaining battery performance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Lithium carbonate is incorporated into the positive electrode active material before battery assembly. This preliminary inclusion ensures that the lithium carbonate is already positioned to react with and neutralize harmful components of the electrolyte before they can cause decomposition of the active material during battery operation

Inventive Principle:

Principle #10Preliminary action

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

This configuration enhances the durability and output characteristics of the battery by limiting NiO formation and maintaining efficient charge/discharge performance while stabilizing the battery's lithium content.

Implementation Method 1

when the nonaqueous electrolyte decomposes in a high-temperature environment during energization, storage, or the like, NiO2, which is the positive electrode active material, may undergo reductive decomposition and generate NiO

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

a conductive network can be formed between particles of a positive electrode active material to increase the ratio of the positive electrode active material in a positive electrode mixture layer

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20230420648A1Positive electrode plate for lithium-ion rechargeable battery, and lithium-ion rechargeable battery

Publication Date: 2023.12.28 TOYOTA BATTERY CO LTD

AI summary

A positive electrode plate for a lithium-ion rechargeable battery includes a positive electrode mixture layer. In the positive electrode mixture layer, a fibrous conductor is combined with a positive electrode active material in which an amount of lithium carbonate with respect to the positive electrode active material is between 0.31 wt % and 1.29 wt %, inclusive. A composition ratio of the fibrous conductor to the positive electrode active material is between 0.5 wt % and 2.0 wt %, inclusive. A coverage of the fibrous conductor to the positive electrode active material is 11.0% or less.