Lithium-Ion Battery Anode Crosslinked Binder High Active Material Loading
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Solution Overview
Problem
Current methods for manufacturing lithium-ion battery anodes face challenges such as high solvent evaporation risks, mechanical cohesion issues, and limited active material mass fraction, which affect the battery's capacity and cyclability.
Innovation Solution
A polymeric anode composition using a crosslinked elastomeric binder with non-hydrogenated acrylonitrile-butadiene copolymer (NBR) or hydrogenated acrylonitrile-butadiene copolymer (HNBR) with a high acrylonitrile content, crosslinked by thermal oxidation, combined with a high mass fraction of graphite and an electrically conductive filler, to enhance the anode's capacity and cyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the mass fraction of active material in the anode is increased to at least 85% to achieve sufficient capacity, then the battery capacity is improved, but the viscosity of the mixture becomes very high which causes overheating and loss of mechanical cohesion
Solution Approach 1:
The patent changes the chemical composition parameters of the binder system by using a specific ratio of carboxylated polybutadiene (1-5 parts by mass) combined with polyacrylonitrile (95-90 parts by mass). This parameter optimization allows achieving the required mechanical cohesion at high active material content (≥85%) without excessive viscosity, resolving the contradiction between capacity and mechanical strength
Solution Approach 2:
The patent employs a composite binder system combining two different polymers with complementary properties: carboxylated polybutadiene provides adhesion and flexibility while polyacrylonitrile contributes to mechanical strength and stability. This composite approach enables the anode to maintain mechanical cohesion at high active material concentrations, solving the viscosity and cohesion problem
2Ease of manufacture
If solvent evaporation is used in the manufacturing process to form the anode, then the electrode structure is formed, but high levels of toxic or flammable organic solvents must be evaporated which creates environmental and safety problems
Solution Approach 1:
The patent completely removes the organic solvent from the manufacturing process by using a slurry formulation that can be directly applied and cured. The binder system is designed to function without requiring solvent evaporation, thereby eliminating the harmful factor of toxic and flammable solvent emissions while maintaining ease of manufacture through a simplified process
Solution Approach 2:
The patent replaces the traditional solvent-based system with a water-based or solvent-free slurry system that uses inexpensive, non-toxic components. The binder polymers are selected to provide adequate performance without requiring expensive solvent handling infrastructure, making the process both safer and more economical
3Object-affected harmful factors
If an aqueous solvent is used to manufacture the anode to avoid organic solvent hazards, then safety and environmental issues are resolved, but the anode must be dried very thoroughly which limits useful life if water traces remain
Solution Approach 1:
The patent extracts water from the processing system by using a solvent-free or organic-solvent-based slurry that cures without requiring extensive drying. The binder system is formulated to achieve adequate curing and mechanical properties without water, thereby eliminating the reliability issue of water traces while maintaining safety benefits
Solution Approach 2:
The patent introduces a curing mechanism as an intermediary process that transforms the binder system from a slurry state to a functional state without requiring water removal. The curing process (thermal or chemical) acts as a mediator that achieves both safety (no organic solvents) and reliability (no water traces) simultaneously
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 achieves significantly improved capacity and retention rates after multiple cycles, with capacities greater than 200 mAh/g and retention rates exceeding 80% after five or ten cycles, while eliminating the need for volatile organic compounds and enhancing mechanical strength.
Implementation Method 1
crosslinked by thermal oxidation
Data Source
AI summary
The invention relates to a polymer composition for an electrode, suitable for forming a lithium-ion battery anode, the preparation method thereof, this electrode and a lithium-ion battery including same. This composition comprises an active material which comprises a graphite usable in the anode, an electrically conductive filler and a cross-linked elastomer binder that comprises at least one hydrogenated acrylonitrile butadiene copolymer (HNBR). According to the invention, said binder comprises at least one non-hydrogenated acrylonitrile butadiene copolymer (NBR) and/or at least one HNBR with an acrylonitrile content by weight greater than or equal to 40% and cross-linked by thermal oxidation. This preparation method comprises successively: a) mixing ingredients of the composition, comprising the active material, the binder in a non-cross-linked state and the electrically conductive filler, in order to obtain a precursor mixture of the composition, b) depositing said mixture on a metal current collector so that said mixture forms a non-cross-linked film, then c) thermal oxidation of said non-cross-linked film under an atmosphere containing oxygen at a temperature of between 200 and 300°C, in order to obtain said electrode in which said binder is cross-linked.