Positive Electrode Active Material Coating for Lower Reaction Resistance
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Solution Overview
Problem
Conventional methods for reducing reaction resistance in lithium ion secondary batteries' positive electrodes are insufficient, limiting output characteristics.
Innovation Solution
A positive electrode active material comprising lithium-containing transition metal oxide secondary particles with tungsten and boron compounds, where tungsten is present between primary particles and boron is distributed to enhance lithium ion conductivity, reducing reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a lithium tungstate compound is adhered to the surface of primary particles to increase battery output, then the reaction resistance is reduced, but the reduction is insufficient and output characteristics remain limited
Solution Approach 1:
The patent applies composite materials by combining tungsten compounds and boron compounds to form a dual-component coating on the positive electrode active material surface. This composite structure synergistically reduces reaction resistance more effectively than single compounds alone, directly resolving the insufficiency of conventional lithium tungstate coating methods
Solution Approach 2:
The patent changes the chemical composition parameters of the surface coating by introducing both tungsten compounds (0.03-0.5 mass%) and boron compounds (0.003-0.1 mass%), optimizing their ratios to achieve minimum reaction resistance. This parameter optimization enables sufficient reaction resistance reduction that was unattainable with conventional single-compound approaches
2Reliability
If tungsten compound amount is increased to further reduce resistance, then reaction resistance decreases, but tungsten elution increases causing battery degradation
Solution Approach 1:
The boron compound acts as an intermediary that stabilizes the tungsten compound on the electrode surface. This intermediary role prevents excessive tungsten elution while maintaining the resistance-reducing benefits, allowing optimal tungsten content to be achieved without harmful elution effects
Solution Approach 2:
The patent optimizes the tungsten compound content within a specific range (0.03-0.5 mass%) and combines it with boron compound (0.003-0.1 mass%), creating a balanced composition that achieves minimum reaction resistance while suppressing tungsten elution below harmful levels
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 described configuration significantly lowers reaction resistance and enhances output characteristics by optimizing the distribution and amounts of tungsten and boron, improving lithium ion transfer and conductivity.
Implementation Method 1
a tungsten compound and a boron compound that are present between at least the primary particles... improving lithium ion transfer and conductivity
Data Source
AI summary
This positive electrode active substance for a non-aqueous electrolyte secondary battery contains: a lithium-containing transition metal oxide having secondary particles formed by aggregation of primary particles; and at least a tungsten compound and a boron compound that are present between primary particles. The present invention is characterized in that: the amount of tungsten element eluted when the positive electrode active substance is washed for 5 minutes with a 0.01 mol/L aqueous solution of sodium hydroxide is 60% or less of the amount of tungsten element detected when the positive electrode active substance is dissolved in a mixed acid containing hydrofluoric acid, nitric acid and hydrochloric acid; and the amount of boron element eluted when the positive electrode active substance is washed for 1 minute with ion exchanged water is 80% or more of the amount of boron element detected when the positive electrode active substance is dissolved in hydrochloric acid.