Lithium-Sulfur Battery Electrolyte With MgCl2 Protective Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The commercialization of lithium-sulfur batteries is hindered by the reduction in charging/discharging efficiency and lifetime due to side reactions, dendrite formation, and the leaching of lithium polysulfide, which leads to the consumption of salts and additives in the electrolyte solution.
Innovation Solution
Incorporating magnesium chloride (MgCl2) into the electrolyte solution to form a stable electrode protective layer, along with specific solvents and lithium salts, to inhibit dendrite growth and improve lithium charging/discharging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as negative electrode active material to achieve high energy density, then capacity density and specific energy are improved, but dendrite growth occurs causing short circuit and reducing lifetime
Solution Approach 1:
The patent introduces lithium nitrate (LiNO3) as an intermediary substance in the electrolyte solution. LiNO3 decomposes to form a stable solid electrolyte interphase (SEI) layer on the lithium metal surface, which acts as a protective barrier. This intermediary layer prevents direct contact between lithium metal and the electrolyte, thereby suppressing dendrite growth and side reactions while maintaining high energy density benefits
2Use of energy by moving object
If sulfur is used as positive electrode active material to achieve high capacity, then energy density is improved, but lithium polysulfide leaching occurs causing shuttle phenomenon and capacity loss
Solution Approach 1:
The patent uses lithium nitrate as an intermediary that forms a protective interface layer between the electrodes and electrolyte. This layer reduces the solubility of lithium polysulfide in the electrolyte solution, preventing its migration from the positive electrode to the negative electrode. The intermediary layer thus suppresses the shuttle phenomenon and prevents capacity loss while maintaining high energy density
3Ease of operation
If conventional electrolyte solution is used to enable battery operation, then charging/discharging function is achieved, but side reactions consume salts and additives continuously reducing lifetime
Solution Approach 1:
The patent applies preliminary action by having lithium nitrate decompose during initial charging cycles to form a stable solid electrolyte interphase (SEI) layer on the lithium metal surface. This pre-formed protective layer prevents subsequent continuous consumption of electrolyte salts and additives through side reactions. The preliminary formation of this stable interface ensures long-term operational stability while maintaining charging/discharging functionality
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 electrolyte solution enhances the lifetime and efficiency of lithium secondary batteries by forming a protective layer that prevents the consumption of salts and additives, thereby improving the battery's capacity and reducing dendrite formation.
Implementation Method 1
magnesium chloride (MgCl2), which forms a stable electrode protective layer on the lithium negative electrode
Implementation Method 2
lithium nitrate, which decomposes to form a protective film on the lithium negative electrode
Implementation Method 3
lithium ions move between the positive and negative electrodes during charging and discharging
Data Source
Figure 1
AI summary
Disclosed is an electrolyte solution for a lithium secondary battery capable of improving the lifetime of a lithium secondary battery, by including a certain amount of magnesium chloride (MgCl2) in the electrolyte to form a stable electrode protective layer that prevents the consumption of salts and additives in the electrolyte solution, and a lithium secondary battery comprising the same. The electrolyte solution for the lithium secondary battery comprises a first solvent comprising a heterocyclic compound containing one or more double bonds or not and containing at least one of an oxygen atom and a sulfur atom; a second solvent comprising at least one of an ether-based compound, an ester-based compound, an amide-based compound, and a carbonate-based compound; a lithium salt; magnesium chloride; and lithium nitrate.