Negative Electrode SEI Pre-Formation for Low-Resistance Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face issues with increased interfacial resistance and capacity degradation due to the decomposition of electrolyte salts, leading to self-discharge and potential heat generation and ignition, especially when using solid polymer electrolytes which are more susceptible to these problems.
Innovation Solution
A method of manufacturing a negative electrode involving a metal thin film with a first solid electrolyte layer formed using a composition containing specific salts and a glyme-based solvent, along with a second solid electrolyte layer including inorganic oxide particles and a polymer, to stabilize the electrolyte layer and reduce interfacial resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid polymer electrolyte is used in the lithium secondary battery, then the safety of the battery is improved, but the interfacial resistance increases significantly
Solution Approach 1:
The patent introduces a liquid electrolyte as an intermediary layer between the solid polymer electrolyte and the negative electrode. This liquid electrolyte mediator facilitates lithium ion transport across the interface while reducing interfacial resistance, thereby maintaining the safety benefits of the solid polymer electrolyte without suffering from its high interfacial resistance problem.
Solution Approach 2:
The patent creates a composite electrolyte system combining solid polymer electrolyte and liquid electrolyte. The solid polymer electrolyte provides safety through mechanical stability and flame resistance, while the liquid electrolyte component reduces interfacial resistance and enhances ionic conductivity at the electrode interface, achieving synergistic performance.
2Ease of manufacture
If the SEI membrane is incompletely formed on the negative electrode, then the manufacturing process is simpler, but the interfacial resistance increases and capacity characteristics degrade
Solution Approach 1:
The patent performs preliminary SEI membrane formation by cycling the half-cell before final battery assembly. This preliminary action ensures complete and uniform SEI membrane formation on the negative electrode surface, preventing subsequent electrolyte decomposition and maintaining low interfacial resistance, while the pre-formation process itself is integrated into the manufacturing workflow.
3Use of energy by moving object
If the battery is overcharged to maximize capacity utilization, then the energy output is improved, but the electrolyte decomposes actively causing heat generation and potential ignition
Solution Approach 1:
The patent forms a stable and uniform SEI membrane on the negative electrode before the battery enters service. This pre-formed protective layer acts as a cushion that prevents direct contact between the electrolyte and electrode during overcharge conditions, suppressing active decomposition reactions and reducing heat generation risk while allowing maximum capacity utilization.
4Stability of the object's composition
If salts in the electrolyte react further with the negative electrode surface after SEI membrane formation, then the SEI membrane thickness increases unevenly, but this leads to a decomposition chain reaction and self-discharge
Solution Approach 1:
The patent employs a feedback mechanism through half-cell cycling to monitor and control SEI membrane formation. By cycling the half-cell and measuring voltage-current characteristics, the process ensures complete SEI membrane formation before final assembly, preventing subsequent electrolyte salt reactions that would cause uneven thickness and decomposition chain reactions.
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 method effectively suppresses further electrolyte decomposition, stabilizes the solid electrolyte layer, and improves the capacity characteristics of lithium secondary batteries by reducing interfacial resistance, enhancing safety and performance.
Implementation Method 1
the electrolyte is reductively decomposed on the negative electrode during the activation or charging/discharging of the battery
Implementation Method 2
The product formed by reductively decomposing the electrolyte forms a solid electrolyte interphase (SEI) membrane which may allow lithium ions to permeate
Data Source
Figure 1~2
Figure 3~4
AI summary
Provided are a method of manufacturing a negative electrode for a lithium secondary battery, which includes: preparing a working electrode including a metal thin film; preparing a composition for forming a first solid electrolyte layer including an additive including at least one salt selected from salts represented by Chemical Formula 1 to Chemical Formula 5 and a glyme-based solvent; fabricating a half-cell including the working electrode, a counter electrode, a reference electrode, and the composition for forming a first solid electrolyte layer; forming a first solid electrolyte layer on the working electrode by operating the half-cell; and separating the working electrode on which the first solid electrolyte layer has been formed, and a negative electrode for a lithium secondary battery manufactured by the above-described method.