Amorphous Polymer Layer on Electrode for Uniform SEI Formation
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Solution Overview
Problem
Existing lithium ion batteries face issues with non-uniform Solid Electrolyte Interface (SEI) formation due to crosslinked polymer layers on electrode surfaces, leading to increased gas yield, resistance, and deterioration of cycle and rate characteristics.
Innovation Solution
A lithium ion battery using a polymer gel electrolyte with an amorphous polymer layer formed on the electrode active material surface, where the pre-gel solution is injected and gelatinized during charging to create a uniform SEI, reducing resistance and enhancing cycle and rate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a crosslinked polymer layer is formed on the electrode surface before SEI formation, then the electrolyte flowability is suppressed, but the SEI formation becomes non-uniform and resistance increases
Solution Approach 1:
The patent applies preliminary action by forming the SEI layer first through initial charging cycles before the crosslinked polymer gel electrolyte is fully formed. This sequence ensures uniform SEI formation on the electrode surface, preventing the non-uniformity and resistance issues that would occur if the polymer layer were present first. The SEI-forming agent is introduced in the electrolyte solution before gelation, allowing it to act during the critical early charging phase.
2Reliability
If a crosslinked polymer gel electrolyte is used, then electrolyte flowability is suppressed for safety, but cycle characteristics and rate characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by carefully controlling the crosslinking degree of the polymer gel electrolyte. Instead of using highly crosslinked structures that improve safety but harm performance, the invention uses a controlled, moderate crosslinking level that maintains sufficient electrolyte mobility for good cycle and rate characteristics while still providing the safety benefits of reduced flowability. This optimization balances the competing requirements of safety and performance.
3Object-affected harmful factors
If a crosslinked polymer gel electrolyte is used, then electrolyte flowability is suppressed, but gas yield increases
Solution Approach 1:
The patent applies preliminary action by ensuring complete and uniform SEI formation before the polymer gel electrolyte undergoes full crosslinking. The SEI layer acts as a protective interface that prevents subsequent decomposition reactions that would generate gas. By establishing this stable interface first, the invention prevents gas generation while maintaining the flowability-suppressing benefits of the crosslinked gel structure.
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 a lithium ion battery with improved rate and cycle characteristics by forming a uniform amorphous polymer layer on the electrode surface, suppressing ion conduction resistance and ensuring stable SEI formation for long-term performance.
Implementation Method 1
the pre-gel solution is injected and gelatinized during charging to create a uniform SEI
Implementation Method 2
forming a uniform amorphous polymer layer on the electrode surface, suppressing ion conduction resistance
Data Source
AI summary
A polymer gel electrolyte containing at least a lithium salt and an aprotic solvent, in which an amorphous polymer layer is formed on the surface of an electrode active material.