Sodium-Ion Battery Electrolyte for Suppressing Dendrite Growth
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Solution Overview
Problem
Current sodium-ion batteries suffer from poor cycling performance, which limits their application due to the uneven deposition of sodium ions forming dendrites during charging.
Innovation Solution
A secondary battery design incorporating a negative electrode film layer with carbon materials and an electrolyte containing both sodium and lithium salts, where lithium ions with higher positive charge density are preferentially adsorbed, forming a charge shielding layer that suppresses sodium dendrite growth, thereby enhancing cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sodium-ion batteries use only sodium salts in the electrolyte, then the battery can operate with sodium-ion active materials, but sodium ions deposit unevenly forming dendrites during charging, leading to poor cycling performance
Solution Approach 1:
Lithium ions act as an intermediary substance in the electrolyte, preferentially adsorbing at the negative electrode to form a charge shielding layer that mediates the deposition process of sodium ions, preventing direct uneven deposition of sodium ions and thereby suppressing dendrite formation while maintaining sodium-ion battery operation
Solution Approach 2:
The patent changes the chemical composition parameter of the electrolyte by introducing lithium salts alongside sodium salts, altering the ion distribution and charge density parameters at the electrode interface, which modifies the deposition behavior of sodium ions from uneven dendritic growth to more uniform deposition, thereby improving cycling performance
2Reliability
If lithium ions are added to the electrolyte, then lithium ions form a charge shielding layer that suppresses sodium dendrite growth, but the electrolyte composition becomes more complex
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding lithium salts to the existing sodium salt system, changing the ionic composition and charge density characteristics of the electrolyte to achieve improved dendrite suppression, accepting the increased compositional complexity as a necessary trade-off for enhanced reliability
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 solution significantly improves the cycling performance of sodium-ion batteries by reducing sodium dendrite growth and maintaining optimal lithium ion concentration, leading to better capacity retention rates after multiple cycles.
Implementation Method 1
the carbon material in the negative electrode film layer has free electrons, making it easier to adsorb lithium ions with higher positive charge density
Implementation Method 2
during charging of the secondary battery, lithium ions are distributed at the dendrite tips ahead of sodium ions, effectively reducing the deposition of sodium ions at the sodium dendrite tips
Data Source
AI summary
This application relates to a secondary battery, a battery module, a battery pack, and an electric apparatus. The secondary battery includes: a negative electrode plate including a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector, the negative electrode film layer containing a carbon material; a positive electrode plate including a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, the positive electrode active material layer containing a sodium-ion active material; and an electrolyte disposed between the negative electrode plate and the positive electrode plate, the electrolyte containing sodium salt and lithium salt.