Negative Electrode Ion Exchange Particles Prevent Dendritic Lithium
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Solution Overview
Problem
Lithium ion secondary cells face a reduction in capacity due to the formation of dendritic Li metal on the negative electrode active material, which is conductively disconnected during discharge, leading to reduced lithium ion contribution in charge and discharge reactions.
Innovation Solution
Incorporating ion exchange particles, such as zeolite, kaolinite, or montmorillonite, into the negative electrode mixture layer that adsorb transition metal ions and release cations like gold (Au) or platinum (Pt), which precipitate as metal nanoparticles on the surface of the negative electrode active material, preventing dendritic Li metal formation by promoting layered Li metal growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium is eluted from the positive electrode active material during charging, then lithium ions are stored in the negative electrode, but dendritic Li metal forms on the surface of the negative electrode active material causing capacity reduction
Solution Approach 1:
Metal nanoparticles (Au, Pt, or Cu) serve as intermediary substrates between the negative electrode active material and lithium ions. These nanoparticles promote uniform lithium deposition and prevent dendrite formation by providing a controlled interface for lithium insertion, thus maintaining both high lithium storage capacity and stable cell performance
Solution Approach 2:
The invention changes the physical and chemical parameters of the negative electrode surface by introducing metal nanoparticles with specific properties (conductivity, surface area, catalytic activity). This modifies the lithium deposition behavior from dendritic growth to uniform layer formation, resolving the contradiction between capacity and reliability
2Object-affected harmful factors
If transition metal ions are present in the electrolytic solution, then they can be adsorbed by protective layers, but metal nanoparticles cannot be effectively formed on the negative electrode active material
Solution Approach 1:
The invention extracts and removes transition metal ions from the electrolytic solution using protective layers containing inorganic compounds (alumina, silica, titania, zirconia, or zeolites) before these ions can interfere with metal nanoparticle formation. This purification step enables precise control of nanoparticle synthesis on the negative electrode active material surface
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 use of ion exchange particles with Au or Pt ensures a large number of metal nanoparticles are attached to the negative electrode active material, preventing dendritic Li metal formation and effectively suppressing capacity reduction in lithium ion secondary cells.
Implementation Method 1
ion exchange particles that adsorb transition metal ions and release cations, and at least one of gold (Au) and platinum (Pt) is present in the ion exchange particles
Implementation Method 2
ion exchange particles that adsorb transition metal ions
Implementation Method 3
release cations like gold (Au) or platinum (Pt), which precipitate as metal nanoparticles on the surface of the negative electrode active material
Implementation Method 4
a plurality of metal nanoparticles including at least one of gold (Au) and platinum (Pt) are attached to the surface of the negative electrode active material... promoting layered Li metal growth
Data Source
AI summary
A technique of preventing the formation of dendritic Li metal on a negative electrode active material surface and suppressing a reduction in cell capacity. In the negative electrode for a lithium ion secondary cell, a negative electrode mixture layer including a negative electrode active material is formed on a foil-shaped negative electrode current collector surface, ion exchange particles that adsorb transition metal ions and release prescribed cations are included in the negative electrode mixture layer, and gold and/or platinum is present in the ion exchange particles. As a result, a large number of metal nanoparticles derived from cations of Au (or Pt) released from the ion exchange particles attach to the negative electrode active material. Since layered Li metal can be easily formed using such metal nanoparticles as metal nuclei, formation of dendritic Li metal is prevented and a reduction in cell capacity can be suppressed.