Non-fluorinated Polymer Binder for Li-ion Battery Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries face challenges in maintaining charge-discharge characteristics across a wide temperature range due to the trade-off between high and low temperature performance, with existing binders either deteriorating at high temperatures or failing at low temperatures.
Innovation Solution
A lithium ion secondary battery electrode comprising a non-fluorinated polymer with specific elution and swelling ratios in an electrolytic solution solvent, combined with an active material, thickener, and conductive auxiliary agent, is developed to improve charge-discharge characteristics across a wide temperature range by optimizing the polymer composition and manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If SBR-based aqueous dispersion is used as a binder, then manufacturing cost is reduced and work environment is improved, but binding strength decreases at high temperature
Solution Approach 1:
The patent uses a composite binder system combining SBR (styrene-butadiene rubber) with CMC (carboxymethyl cellulose) and starch. This composite approach leverages the strong binding properties of SBR while CMC and starch provide thermal stability, preventing binder degradation at high temperatures. The combination maintains both manufacturing advantages and high-temperature performance.
Solution Approach 2:
The patent optimizes the composition ratios of the binder components, specifically setting SBR at 90-99 parts by weight, CMC at 1-10 parts by weight, and starch at 1-10 parts by weight. This parameter optimization ensures the binder maintains appropriate viscosity, binding strength, and thermal stability without compromising manufacturing cost-effectiveness.
2Strength
If PVDF is used as a binder to obtain sufficient binding strength, then binding strength is improved, but active material content is decreased and manufacturing cost is increased
Solution Approach 1:
The patent replaces pure PVDF with a composite binder system using SBR as the primary binder (90-99 parts), supplemented by CMC (1-10 parts) and starch (1-10 parts). This composite approach achieves sufficient binding strength through the synergistic effects of the components, allowing higher active material content while maintaining electrode integrity.
Solution Approach 2:
The patent substitutes expensive PVDF with cheaper alternatives - SBR-based aqueous dispersion combined with CMC and starch. This replacement reduces binder cost while maintaining binding performance, thereby increasing the proportion of active material in the electrode and reducing overall manufacturing cost.
3Strength
If SBR is used as a binder, then binding properties are improved, but electrolytic solution resistance increases and charge-discharge characteristics deteriorate at high temperature
Solution Approach 1:
The patent combines SBR with CMC and starch to create a composite binder that maintains SBR's excellent binding properties while adding thermal stability. The CMC and starch components prevent excessive swelling and electrolyte absorption at high temperatures, thereby maintaining charge-discharge characteristics while preserving strong binding properties.
Solution Approach 2:
The patent carefully controls the composition parameters, limiting CMC to 1-10 parts by weight and starch to 1-10 parts by weight relative to 100 parts of SBR. This optimization ensures the binder maintains appropriate electrolytic solution resistance and thermal stability without compromising the superior binding properties of SBR.
Data Source
AI summary
A lithium ion secondary battery electrode according to the present invention includes (A) a non-fluorinated polymer; (B) an active material; (C) a thickener; and (D) a conductive auxiliary agent. An elution ratio of (A) the non-fluorinated polymer in an electrolytic solution solvent at 60° C. is equal to or less than 1.0 mass %, and a swelling ratio of (A) the non-fluorinated polymer in the electrolytic solution solvent at 60° C. is equal to or more than 10 mass % and equal to or less than 50 mass %.