Negative Electrode Pre-Lithiation Using Dual Electrolyte Assemblies
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Solution Overview
Problem
Current lithium-ion batteries face challenges in efficiently cycling lithium ions due to limitations in electrode materials and electrolytes, which affect their performance and longevity, particularly in automotive applications where high energy storage and power demands are required.
Innovation Solution
The method involves preparing an electrochemical cell by applying a potential to a first assembly with an aqueous electrolyte containing a lithium salt, which dissociates into cations and anions, and a second assembly with a non-aqueous electrolyte, using a lithium ion-conducting separator to form a lithium film or interact with a precursor electroactive material, specifically utilizing metal oxides, silicon-containing materials, and specific solvents and additives to enhance lithium ion conductivity and cycling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode materials and electrolytes are used, then the battery structure is simple, but the cycling efficiency and longevity are insufficient for automotive applications
Solution Approach 1:
The patent applies preliminary action by forming a stable lithium film on the negative electrode before the battery is put into service. This is achieved through a two-electrolyte system where lithium ions are deposited onto the negative electrode during an initial conditioning phase, creating a protective layer that prevents subsequent electrolyte decomposition and improves cycling longevity.
Solution Approach 2:
The patent introduces a lithium ion-conducting separator as an intermediary component between the positive and negative electrodes. This separator not only allows ion transport but also facilitates the transfer of lithium ions from the aqueous electrolyte side to form the stabilizing lithium film on the negative electrode, mediating the interaction between the two electrolyte systems.
2Reliability
If a two-electrolyte system with aqueous and non-aqueous electrolytes is used, then lithium ion conductivity and cycling efficiency are improved, but the device complexity increases
Solution Approach 1:
The patent segments the electrolyte system into two distinct compartments: an aqueous electrolyte compartment containing lithium salts and a non-aqueous electrolyte compartment containing carbonate solvents. This segmentation allows each electrolyte to be optimized for its specific function while being separated by a lithium ion-conducting separator, improving overall system performance.
Solution Approach 2:
The patent applies local quality by assigning different electrolyte compositions to different regions of the battery. The aqueous electrolyte is used where high lithium ion conductivity is needed for film formation, while the non-aqueous electrolyte is used where stability and voltage window are critical. Each local region has electrolyte properties optimized for its specific functional requirements.
3Quantity of substance
If high concentrations of lithium salts are used in the aqueous electrolyte, then lithium ion availability increases, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the parameter of lithium salt concentration in the aqueous electrolyte to optimize lithium ion availability. By adjusting the concentration of lithium salts such as LiCl, LiBr, or LiI within specific ranges, the system achieves sufficient lithium ion supply for film formation without requiring excessively high concentrations that would complicate manufacturing and increase costs.
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
This approach improves the cycling efficiency and longevity of lithium-ion batteries by forming a stable lithium film or pre-lithiated electroactive material, enhancing their performance in energy storage and power delivery, particularly in automotive applications.
Implementation Method 1
The lithium salt disassociates forming cations and anions
Implementation Method 2
a lithium ion-conducting separator... as the potential is applied the lithium salt disassociates forming cations and anions. The electroactive material may be formed as the cations move from the first assembly through the lithium ion-conducting separator towards the second electrode
Implementation Method 3
The cations moving from the first assembly through the lithium ion-conducting separator towards the second electrode may include lithium and may form a lithium film that defines the electroactive material
Implementation Method 4
the cations moving from the first assembly through the lithium ion-conducting separator may interact with the precursor electroactive material to form the electroactive material... the precursor electroactive material may include a silicon-containing electroactive material... and the electroactive material may include a pre-lithiated silicon-containing electroactive material
Data Source
AI summary
A method for preparing an electroactive material for an electrochemical cell that cycles lithium ions includes applying a potential to a first assembly that includes a first electrode and an aqueous electrolyte. The aqueous electrolyte includes a lithium salt and as the potential is applied the lithium salt disassociates forming cations and anions. The first assembly is physically separated from a second assembly by a lithium ion-conducting separator. The second assembly includes a second electrode and a non-aqueous electrolyte. The electroactive material is formed as the cations move from the first assembly through the lithium ion-conducting separator towards the second electrode.