Negative Electrode Active Material Coating for Dendrite Suppression
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Solution Overview
Problem
The existing lithium secondary batteries face issues with stability and life performance due to the formation of a passivation film containing Li2CO3, which has low ion conductivity, leading to lithium precipitation and dendrite formation, causing overcharge and resistance increases.
Innovation Solution
A method of preparing a negative electrode active material by dispersing an active material core in a surfactant solution, followed by adding lithium compound precursors through electrostatic attraction, and forming a protective layer containing a lithium compound via hydrothermal reaction and heat treatment to enhance ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If Li2CO3 is present in the solid electrolyte interface layer, then the structure is stabilized, but lithium ion diffusion is concentrated on LiF or interface causing overcharge and resistance increase phenomenon
Solution Approach 1:
The invention changes the compositional parameters of the passivation film by controlling the relative amounts of lithium sources versus carbon sources in the electrolyte formulation, and by introducing specific additives, to achieve a film composition that prevents lithium ion concentration and subsequent precipitation
Solution Approach 2:
The invention uses dissolved lithium salts in the electrolyte as an intermediary substance that fills voids and interfaces within the passivation film, creating a more uniform lithium ion distribution pathway and preventing concentration at specific locations that would lead to precipitation
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 method improves the ionic conductivity and life performance of the negative electrode by uniformly coating a lithium compound on the active material core, preventing lithium precipitation and dendrite formation, thus enhancing rapid charging capabilities.
Implementation Method 1
coat the surfactant on the active material core; adding and dispersing a first precursor, which is bondable with the surfactant by electrostatic attraction
Implementation Method 2
preparing a lithium compound precursor by a hydrothermal reaction of the first precursor and the second precursor in the solution
Implementation Method 3
performing a heat treatment on the lithium compound precursor to thermally decompose the surfactant, and forming a protective layer containing a lithium compound on the active material core
Data Source
AI summary
Disclosed is a method of preparing a negative electrode active material which includes (a) dispersing an active material core in a solution containing a surfactant to coat the surfactant on the active material core, (b) adding and dispersing a first precursor, which is bondable with the surfactant by electrostatic attraction, in the solution, (c) adding and dispersing a second precursor, which is bondable with the first precursor by electrostatic attraction, in the solution, (d) preparing a lithium compound precursor by a hydrothermal reaction of the first precursor and the second precursor in the solution, and (e) performing a heat treatment on the lithium compound precursor to thermally decompose the surfactant, and forming a protective layer containing a lithium compound on the active material core, wherein one of the first precursor and the second precursor is at least one selected from lithium hydroxide, lithium oxide, lithium nitrate or lithium sulfate.