Electrolyte Medium Composition for Dendrite-Resistant Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high energy density and high output while preventing short circuits, which are exacerbated by the use of lithium metal due to dendrite formation and safety concerns, and nonwoven fabric separators compromise cycle stability and safety.
Innovation Solution
An electrolyte medium for lithium secondary batteries comprising a low dielectric constant solvent, a lithium salt, and a polyvalent cation salt dispersed as particles, which forms a bulky solid electrolyte interphase layer, allowing the use of lithium metal and nonwoven fabric separators to suppress short circuits and enhance energy density and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used to achieve high energy density, then energy density is improved, but dendrite formation causes short circuits and safety issues
Solution Approach 1:
The patent introduces a nonwoven fabric separator as an intermediary component between the lithium metal electrodes. This separator has high porosity (90% or more) that allows lithium ion transport while physically preventing direct contact between lithium metal surfaces, thus eliminating short circuits while maintaining high energy density benefits of lithium metal
Solution Approach 2:
The patent employs a nonwoven fabric separator with extremely high porosity (90% or more). This porous structure enables efficient lithium ion conduction paths while the three-dimensional network architecture provides mechanical separation of electrodes, preventing dendrite-induced short circuits and enabling safe use of lithium metal for high energy density
2Power
If a nonwoven fabric separator with high porosity is used to increase output, then output is improved, but short circuit prevention and cycle stability deteriorate
Solution Approach 1:
The patent utilizes a nonwoven fabric separator with porosity of 90% or more, which creates extensive open spaces for rapid lithium ion diffusion, thereby increasing battery output. The high porosity reduces ion transport resistance while the fibrous network structure maintains electrode separation, achieving both high power and reliability
Solution Approach 2:
The nonwoven fabric separator acts as a mediator that enables high output through its porous structure facilitating fast ion transport, while simultaneously preventing short circuits by maintaining physical separation between electrodes. This intermediary component resolves the contradiction between high porosity for output and short circuit prevention
3Reliability
If coating or alloying of lithium metal is performed to prevent dendrite formation, then short circuit suppression is improved, but manufacturing complexity and oxidation risk increase
Solution Approach 1:
The patent extracts the dendrite suppression function from complex surface treatments (coating or alloying) and transfers it to a separate component - the nonwoven fabric separator. By removing the need for complicated lithium metal surface modifications and relying instead on the separator's physical structure, manufacturing complexity is reduced while maintaining effective dendrite suppression
Solution Approach 2:
The nonwoven fabric separator serves as an intermediary that provides dendrite suppression without requiring modification of the lithium metal itself. This approach avoids the oxidation risks and process complexities associated with coating or alloying lithium metal, as the separator passively prevents dendrite formation through its physical barrier and ion distribution effects
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 medium effectively suppresses short circuits, enabling lithium secondary batteries to achieve high energy density and high output with stable cycle characteristics and improved safety, even with lithium metal and high-porosity nonwoven fabric separators.
Implementation Method 1
it has been reported that a stable layer is formed on lithium metal by complexation with an inorganic substance such as magnesium oxide
Implementation Method 2
in a lithium secondary battery using a redox reaction of lithium
Data Source
AI summary
To provide a lithium secondary battery capable of suppressing short circuits and having high energy density and high output. An electrolyte medium for a lithium secondary battery includes a low dielectric constant solvent, a lithium salt, and a polyvalent cation salt. The polyvalent cation salt is dispersed as particles in the electrolyte medium and can flow without being immobilized. The electrolyte medium includes 20 mass % or less of a high dielectric constant solvent. A lithium secondary battery including the electrolyte medium for a lithium secondary battery can suppress short circuits and provide high energy density and high output.