Active Material Composite Coating for Li-Ion Cycle and Rate Performance
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges with poor cycle and rate characteristics due to low conductivity of electrode active materials, particularly when using Si or Si alloys as anode active materials, which also require high-temperature carbonization processes for improved performance.
Innovation Solution
A composition comprising active materials, conductive carbon, and dispersants like vinyl polymers with pendant oxazoline groups and triarylamine-based hyperbranched polymers is used to form a uniform coating layer on active material particles, enhancing conductivity and durability without the need for high-temperature carbonization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si or Si alloy is used as anode active material to increase capacity, then capacity per unit weight is improved, but volume expansion occurs causing poor cycle characteristics
Solution Approach 1:
The patent embeds Si or Si alloy particles inside a graphite shell, creating a core-shell structure where the inner Si core provides high capacity while the outer graphite shell accommodates volume expansion and maintains structural integrity during cycling
Solution Approach 2:
The patent creates a composite material combining Si (or Si alloy) with graphite, where the two materials work together to provide both high capacity from Si and structural stability from graphite, resolving the contradiction between capacity and cycle life
2Reliability
If graphite is mixed to solve volume expansion problem, then cycle characteristics are improved, but uneven distribution during mixing degrades cycle life
Solution Approach 1:
The patent pre-forms graphite shells around Si particles before electrode fabrication, ensuring uniform distribution of graphite around each Si particle without requiring precise mixing during electrode preparation
Solution Approach 2:
The patent applies graphite coating locally around each Si particle to create a controlled interface, ensuring that each Si particle is individually protected rather than relying on bulk mixing uniformity
3Reliability
If electrode active material surface is covered with organic compound and carbonized to increase conductivity, then electron conductivity is improved, but high-temperature heat treatment is required
Solution Approach 1:
The patent changes the chemical composition of the coating material from conventional organic compounds to metal oxides with inherent high-temperature stability and conductivity, eliminating the need for high-temperature carbonization while maintaining electron conductivity
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 approach results in active material composites with improved cycle and rate characteristics for lithium-ion batteries, enabling better performance and simplifying the manufacturing process by eliminating the need for high-temperature treatments.
Implementation Method 1
at least one dispersant selected from a vinyl polymer comprising a pendant oxazoline group and a triarylamine-based hyperbranched polymer gives an active material composite that has a uniform coating layer containing a conductive material and the like on the surface of the active material particles
Data Source
AI summary
Provided is a composition for forming an active material composite that gives an active material composite that can be used for an electrode in a lithium ion secondary battery and the like and that can improve battery cycle and rate characteristics.A composition for forming an active material composite comprising at least one active material selected from a metal, a metalloid, a metal alloy, a metal oxide, a metalloid oxide, a metal phosphate, a metal sulfide, and a metal nitride, a conductive material, a solvent, and at least one dispersant selected from a vinyl polymer comprising a pendant oxazoline group and a triarylamine-based hyperbranched polymer.