Porous Separator Coating for Better Li-Ion Electrolyte Infiltration
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Solution Overview
Problem
Conventional lithium-ion battery separators have poor electrolyte solution infiltration and weak ion conductivity due to lyophobic surfaces and low surface energy, limiting fast charging capabilities.
Innovation Solution
A separator with a base material layer and a first coating layer containing a lithium-containing compound, where the ratio of the coating layer thickness to the pore diameter is between 1:4 to 1:500, enhancing electrolyte infiltration and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator material with lyophobic surface is used, then the separator structure is simple and easy to manufacture, but the electrolyte solution infiltration is poor and ion conductivity is weak
Solution Approach 1:
The patent applies composite materials by combining the base separator material (polyolefin or aramid) with a lithium-containing compound coating layer. This composite structure integrates the mechanical strength and thermal stability of the base material with the ion conductivity enhancement provided by the lithium-containing compound, directly resolving the contradiction between simple structure and high ion conductivity.
Solution Approach 2:
The patent utilizes porous materials by maintaining the porous structure of the base separator while coating the inner walls of the pores with lithium-containing compound. The porous structure allows electrolyte penetration and ion transport, while the lithium-containing compound coating enhances ion conductivity without blocking the pores, thus improving ion conductivity while preserving the functional porous structure.
2Reliability
If the coating layer thickness is increased to improve ion conductivity, then the ion conductivity enhances, but the pore diameter is reduced which may block ion transport
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the lithium-containing compound coating layer to a specific range (1 nm to 100 nm). This controlled parameter adjustment ensures that the coating is thick enough to provide sufficient ion conductivity enhancement through lithium ion dissolution, yet thin enough to maintain adequate pore diameter for electrolyte penetration and ion transport.
Solution Approach 2:
The patent applies local quality by coating only the inner walls of the pores with lithium-containing compound rather than filling the entire pore space. This localized application ensures that the coating provides ion conductivity enhancement at the pore surfaces where ion transport occurs, while leaving the central pore channels open for efficient ion flow.
3Reliability
If a thick coating layer is applied to enhance ion conductivity, then the ion conductivity improves, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies mechanics substitution by replacing traditional mechanical coating methods (such as spray coating or dip coating) with atomic layer deposition (ALD). ALD is a vapor-phase deposition technique that provides precise thickness control at the nanometer scale and ensures uniform coating on complex pore structures, thereby improving ion conductivity while maintaining manufacturing feasibility through automated processing.
Solution Approach 2:
The patent applies parameter changes by controlling the ALD process parameters (number of cycles, precursor dosage, temperature) to achieve the optimal coating thickness range of 1 nm to 100 nm. This parameter optimization ensures sufficient ion conductivity enhancement while minimizing the number of deposition cycles required, thus reducing manufacturing complexity and production time.
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 improved separator exhibits excellent performance during high-rate charge and discharge, as well as at low and high temperatures, with enhanced ion conductivity and reduced lithium ion transportation resistance.
Implementation Method 1
The separator plays two basic roles in lithium-ion batteries: electron insulation and ion conduction. During charging of a lithium-ion battery, lithium ions are deintercalated from a positive electrode material, pass through pores of the separator through an electrolyte solution
Implementation Method 2
a coating layer is disposed on an inner wall of a pore in a base material layer of a separator of the present disclosure, and a ratio of a thickness of the coating layer to a pore diameter of the pore is within a specific range, which significantly improves electrolyte solution infiltration
Data Source
AI summary
Disclosed are a separator and a battery including the separator. The separator includes a base material layer and a first coating layer, the base material layer has a porous structure, the porous structure has pores, the first coating layer is located on inner walls of the pores, the first coating layer includes a first lithium-containing compound, and a ratio of a thickness of the first coating layer to a pore diameter of the pores ranges from 1:4 to 1:500. The separator in the present disclosure has good electrolyte solution infiltration and an excellent ion conductivity. The battery including the separator in the present disclosure has excellent performance during high-rate charge and discharge and low-temperature and high-temperature charge and discharge.