Lithium Anode Salt Coating for Stable SEI and Longer Cycle Life
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Solution Overview
Problem
Lithium secondary batteries face performance deterioration due to consumption of salt and additives in the electrolyte, leading to overvoltage and reduced rate characteristics, as these components are not replenished during charging and discharging, affecting the stability of the Solid Electrolyte Interphase (SEI) and causing shuttling of lithium sulfide.
Innovation Solution
A negative electrode with a salt coating layer containing lithium salt and an additive, such as LiFSI and lithium nitrate, is applied between lithium thin films, allowing for replenishment of consumed electrolyte materials and stable SEI formation, thereby improving battery lifetime and preventing lithium sulfide shuttling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If salt and additive are continuously supplied to form SEI, then SEI stability is improved, but battery lifetime deteriorates due to continuous consumption
Solution Approach 1:
The patent applies preliminary action by pre-coating the lithium metal surface with salt and additive materials before battery operation begins. This preliminary coating serves as a reservoir that gradually releases materials during cycling, proactively maintaining SEI stability without requiring continuous external supply during operation.
Solution Approach 2:
The patent implements self-service by designing the negative electrode to contain its own SEI-forming materials (salt and additive) within the porous coating layer. During battery cycling, these materials are gradually released and reused to maintain the SEI, allowing the electrode to self-replenish its protective layer without consuming electrolyte components from the bulk electrolyte.
2Reliability
If excessive amount of salt and additive is used to form SEI, then SEI formation is improved, but rate characteristics deteriorate due to overvoltage
Solution Approach 1:
The patent applies local quality by concentrating the salt and additive materials specifically at the lithium metal surface where SEI formation is needed, rather than uniformly distributing them throughout the entire electrolyte. The porous coating layer ensures localized material availability at the electrode-electrolyte interface, maintaining effective SEI formation without excessive bulk electrolyte concentration that would increase viscosity and reduce rate characteristics.
Solution Approach 2:
The patent implements parameter changes by controlling the composition and thickness of the porous coating layer to optimize the local concentration of salt and additive. By adjusting these parameters in the coating layer, the patent achieves sufficient SEI formation while avoiding the overvoltage and rate characteristic deterioration associated with excessive salt and additive in the bulk electrolyte.
3Reliability
If organic protective layer is applied on lithium metal layer, then lithium-ion conductivity is improved, but electrolyte replenishment function is lost
Solution Approach 1:
The patent applies composite materials by creating a porous coating layer that combines lithium salt, additive, and porous structure in a single integrated layer. This composite structure simultaneously provides lithium-ion conductivity pathways through the porous network and contains reservoirs of salt and additive materials that can be released to replenish the electrolyte, achieving both functions in one component.
Solution Approach 2:
The patent implements multi-functionality by designing the porous coating layer to perform multiple functions: (1) maintaining lithium-ion conductivity during charging/discharging, (2) serving as a reservoir for salt and additive replenishment, and (3) protecting the lithium metal surface. This single component replaces the single-function organic protective layer by integrating both conductivity and replenishment functions.
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 salt coating layer effectively replenishes lithium salt and additives in the electrolyte, maintaining a stable SEI and enhancing the lithium secondary battery's lifetime performance and coulombic efficiency, while preventing lithium sulfide shuttling and delaying battery performance deterioration.
Implementation Method 1
the salt coating layer effectively replenishes lithium salt and additives in the electrolyte
Implementation Method 2
The SEI may be formed by reacting lithium metal with a salt and an additive contained in the electrolyte
Implementation Method 3
improving lithium ion conductivity in the lithium negative electrode
Data Source
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AI summary
The present invention relates to an anode for a lithium secondary battery, a manufacturing method therefor, and a lithium secondary battery comprising same. More specifically, the anode has, between a plurality of lithium thin films, salt-coated layers comprising a lithium salt and an additive, so that, during operation of a battery, the lithium salt and additive of a consumed electrolyte can be replenished while the salt-coated layers dissolve, and thus the lifespan characteristics of the battery can be improved while high cooling efficiency is maintained.