Crosslinked Electrode Binder Composition for Battery Cycle Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with bonding strength and structural stability due to the expansion and contraction of electrode active materials during charge/discharge cycles, leading to reduced capacity and shortened lifespan, as well as swelling phenomena caused by electrolyte decomposition.
Innovation Solution
A binder composition for secondary battery electrodes is developed, comprising a copolymer with specific repeating units derived from conjugated diene-based monomers, aromatic vinyl-based monomers, unsaturated carboxylic acid-based monomers, diacetone acrylamide, and adipic acid dihydrazide, which enhances bonding strength and mechanical properties through crosslinking reactions, preventing migration and maintaining stability even after repeated cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a binder is used to maintain bonding strength between electrode active material and current collector, then bonding strength is improved, but structural stability deteriorates due to expansion and contraction during charge/discharge cycles
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by incorporating specific functional groups (carboxyl, hydroxyl, amine) and using copolymer structures with controlled ratios of different monomers. This allows the binder to maintain appropriate bonding strength while accommodating volume changes during charge/discharge cycles, resolving the contradiction between strong bonding and structural stability
Solution Approach 2:
The patent uses composite binder materials consisting of multiple polymer components with complementary properties. The combination of different functional groups and polymer structures creates a synergistic effect that provides both strong adhesion to electrode materials and flexibility to handle expansion/contraction, thus maintaining both bonding strength and structural stability
2Quantity of substance
If high discharge capacity materials such as silicon, tin, or silicon-tin alloy are used to increase electrode capacity, then discharge capacity is improved, but volume expansion remarkably increases leading to desorption of negative electrode material
Solution Approach 1:
The patent employs a flexible binder matrix that acts as a protective shell around high-capacity materials like silicon and tin. This flexible matrix accommodates the remarkable volume expansion (up to 300%) of these materials during lithiation while maintaining continuous contact and preventing desorption from the current collector, thus preserving both high discharge capacity and bonding strength
3Temperature
If the temperature of batteries is elevated with the use of electronic products, then the decomposition of electrolyte is promoted, but swelling phenomenon is accelerated causing reduction in stability
Solution Approach 1:
The patent introduces a thermally stable binder composition as an intermediary between the electrode materials and the electrolyte. This binder acts as a protective layer that reduces direct contact between the electrolyte and electrode materials at elevated temperatures, thereby suppressing electrolyte decomposition and the resulting swelling phenomenon, and maintaining battery stability under thermal stress
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 binder composition significantly improves the cycle capacity retention ratio, maintaining excellent adhesive strength at both dry and wet states, and enhances the overall performance of lithium secondary batteries by reducing swelling and maintaining structural integrity.
Implementation Method 1
a copolymer including: a first repeating unit derived from a conjugated diene-based monomer; second repeating units derived from one or more monomers selected from the group consisting of b1) an aromatic vinyl-based monomer and b2) an unsaturated carboxylic acid-based monomer; c) a third repeating unit including a crosslinked structure of diacetone acrylamide and adipic acid dihydrazide
Implementation Method 2
maintaining excellent bonding strength between the electrode active material and the current collector
Implementation Method 3
a process in which lithium ions of a positive electrode are repeatedly intercalated and deintercalated at a negative electrode
Data Source
AI summary
Provided are a binder composition for a secondary battery and an electrode mixture including the same. More particularly, provided are a binder composition for a secondary battery, the binder composition having excellent characteristics of binding strength, mechanical properties, etc., while maintaining structural stability of an electrode even after repeated charge/discharge cycles, thereby improving performances of a secondary battery, and an electrode mixture including the same.