Lithium Boron Coated Cathode Suppresses Paste Gelation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face issues with gelation of the positive electrode mixed material paste during production, leading to reduced battery capacity and safety concerns due to residual acidic oxide particles, and the addition of boron or tungsten can exacerbate these problems.
Innovation Solution
A positive electrode active material is developed with a lithium-metal composite oxide and a lithium boron compound, where the lithium boron compound is formed on the surface of the lithium-metal composite oxide particles to control the amount of eluted lithium hydroxide, suppressing gelation and improving battery stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boron or tungsten is added to improve battery characteristics, then output characteristic and cycle characteristic are improved, but gelation of positive electrode mixed material paste occurs and battery capacity decreases
Solution Approach 1:
The invention changes the chemical composition parameters by adding specific elements (Mo, W, Nb, Ta, Re) in controlled amounts (0.01-5 at%) to the lithium-transition metal compound. This parameter adjustment improves output and cycle characteristics while avoiding the gelation problem that occurs with traditional boron or tungsten additions, thus maintaining battery capacity.
Solution Approach 2:
The invention creates a composite material system by combining lithium-transition metal compound with specific additive elements (Mo, W, Nb, Ta, Re) and carbon materials. This composite structure achieves both improved electrochemical performance (output and cycle characteristics) and prevention of paste gelation, resolving the contradiction between reliability and productivity.
2Power
If acidic oxide particles are present in positive electrode composition, then output characteristic is improved, but separator breakage occurs and safety is compromised
Solution Approach 1:
The invention extracts and removes the harmful acidic oxide particles from the positive electrode composition while retaining the beneficial output characteristics through the use of alternative elements (Mo, W, Nb, Ta, Re) that do not cause separator breakage, thus eliminating the harmful effect while preserving the useful effect.
Solution Approach 2:
The invention replaces the problematic acidic oxide particles with alternative elements that provide similar electrochemical benefits without the harmful side effects. The alternative elements act as substitute materials that achieve the same functional goal (improved output characteristic) without causing separator breakage.
3Reliability
If lithium content is increased above stoichiometric composition to improve charge-discharge cycle characteristic, then cycle characteristic is improved, but gelation of paste occurs during production
Solution Approach 1:
The invention introduces intermediary elements (Mo, W, Nb, Ta, Re) that act as mediators between the excess lithium and the binder system. These intermediary elements prevent the direct harmful interaction between excess lithium and the paste components that causes gelation, while allowing the excess lithium to remain for improved cycle characteristics.
Solution Approach 2:
The invention changes the compositional parameters by adding specific elements in controlled amounts to modify the chemical environment in the paste. This parameter change prevents gelation while maintaining the beneficial effect of excess lithium for charge-discharge cycle characteristic.
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 solution effectively suppresses gelation of the positive electrode mixed material paste, enhancing battery stability and maintaining high battery capacity and output characteristics, while reducing the risk of separator breakage and material costs.
Implementation Method 1
a positive electrode active material for a non-aqueous electrolyte secondary battery, in which a lithium-metal composite oxide exists as a particle whose surface is covered with a lithium boron compound
Implementation Method 2
control the amount of eluted lithium hydroxide, suppressing gelation
Data Source
AI summary
The present invention has an object to provide a positive electrode active material for a non-aqueous electrolyte secondary battery which not only suppresses gelation of a positive electrode mixed material paste upon producing the non-aqueous electrolyte secondary battery but also improves the stability thereof. Provided is the positive electrode active material represented by general formula LisNi1−x−y−zCoxMnyMzO2+α (0≤x≤0.35, 0≤y≤0.35, 0≤z≤0.10, 0.95<s<1.30, and 0≤α≤0.2, and M represents at least one element selected from V, Mg, Mo, Nb, Ti, W, and Al) and containing secondary particles formed by agglomeration of primary particles, wherein at least part of the surface of the primary particles thereof is covered with a lithium boron compound, and the amount of redundant lithium hydroxide of the positive electrode active material measured with a neutralization titration is at least 0.003% by mass and up to 0.5% by mass relative to the total of the positive electrode active material.