Differential-Conductivity Electrolyte Layers for Lithium Dendrite Inhibition
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Solution Overview
Problem
Lithium secondary batteries suffer from rapid capacity degradation due to lithium dendrite formation during charging and discharging, leading to short circuits, which existing methods fail to adequately inhibit.
Innovation Solution
A lithium secondary battery design featuring two electrolyte layers with differing ion conductivities, where the first layer facing the negative electrode has higher conductivity than the second layer, creating a differential conductivity gradient to inhibit dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electrolyte solution is used in lithium secondary batteries, then the battery structure is simple and manufacturing is easy, but lithium dendrites form during charging and discharging causing capacity degradation and short circuits
Solution Approach 1:
The electrolyte is divided into multiple distinct layers with different compositions and functions. The first electrolyte layer contains a cyclic carbonate component and the second electrolyte layer contains a chain carbonate component, creating a segmented structure that prevents dendrite formation while maintaining overall battery functionality.
Solution Approach 2:
Different regions of the electrolyte are assigned different local properties tailored to specific functions. The first layer near the electrode has high dielectric constant for efficient charge transfer, while the second layer has low viscosity for good ion mobility, optimizing performance at each location.
2Reliability
If polymer protective layers or inorganic solid protective layers are introduced into lithium metal layers, then some protection against dendrites is provided, but the inhibitory effect is insignificant
Solution Approach 1:
The invention changes the chemical composition parameters of the electrolyte layers rather than adding physical protective layers. By adjusting the ratio of cyclic to chain carbonate components and controlling the concentration of lithium salts in each layer, effective dendrite inhibition is achieved through electrochemical properties rather than mechanical barriers.
3Reliability
If the concentration of salts in electrolyte solution is increased or additives are applied, then some dendrite suppression is achieved, but the effect remains insignificant
Solution Approach 1:
The electrolyte is designed as a composite system with two distinct layers, each containing specific combinations of carbonate solvents and lithium salts. This composite structure enables synergistic effects where the first layer facilitates efficient charging through high dielectric constant properties, while the second layer ensures smooth discharging through low viscosity properties, achieving both dendrite inhibition and high productivity.
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 differential ion conductivity effectively prevents rapid dendrite growth, enhancing operation characteristics, lifetime, and safety of the battery.
Implementation Method 1
the first electrolyte layer has a higher ion conductivity than the second electrolyte layer; wherein a difference in ion conductivity between the first electrolyte layer and the second electrolyte layer is 10 to 100 times
Data Source
Figure 1
AI summary
The present invention relates to an electrolyte comprising a first electrolyte layer facing a negative electrode; and a second electrolyte layer located on the first electrolyte layer, wherein the first electrolyte layer has a higher ion conductivity than the second electrolyte layer, and a lithium secondary battery comprising the electrolyte described above.