Solid State Pretreatment of Silicon Monoxide Negative Electrodes
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Solution Overview
Problem
High-capacity rechargeable batteries face issues with poor cycle life and first-cycle Coulombic efficiency due to irreversible trapping of lithium ions and active materials, which limits their capacity and scalability in industrial manufacturing.
Innovation Solution
The method involves solid state pretreatment of active materials like silicon monoxide with lithium-containing structures, such as lithium hydroxide, to form treated negative active material structures that enhance lithium ion reversibility and distribution, reducing irreversible trapping and improving cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium metal is added to negative electrodes to compensate for lithium ion losses, then first cycle Coulombic efficiency is improved, but uniform distribution of lithium metal on the electrode surface is difficult to achieve and special processing environments are required
Solution Approach 1:
The patent uses lithium-containing compounds (such as lithium hydroxide, lithium carbonate, lithium oxide) as intermediary substances instead of direct lithium metal. These compounds serve as a mediator that releases lithium ions during initial charging cycles, achieving the same compensatory effect while being easier to handle and distribute uniformly on the electrode surface without requiring special processing environments.
Solution Approach 2:
The patent employs disposable lithium-containing compounds that are consumed during initial cycles to provide lithium ions. These compounds are sacrificed in the first few cycles to compensate for irreversible lithium trapping, after which the electrode enters stable cycling. This approach replaces the need for precise lithium metal dosing with a simpler, more manufacturable solution.
2Reliability
If thermal evaporation or molten lithium exposure is used to form lithium metal layers on negative electrodes, then lithium ion compensation is achieved, but the process is hardly scalable for manufacturing
Solution Approach 1:
The patent replaces complex thermal processing systems (thermal evaporation equipment, molten lithium handling systems) with simple mixing and coating processes. Instead of using high-energy thermal fields to deposit lithium, the invention uses mechanical mixing of lithium-containing compounds with the electrode slurry, followed by conventional drying, making the process scalable to industrial manufacturing.
Solution Approach 2:
The patent changes the physical state and chemical form of lithium from metallic lithium requiring thermal processing to lithium-containing compounds that can be processed at lower temperatures. This parameter change from metal to compound form enables the use of standard manufacturing techniques rather than specialized thermal processing equipment.
3Reliability
If prelithiation reagents such as LiF/Co are added to positive electrodes, then future lithium ion losses are compensated, but the reagents are difficult to synthesize and produce significant volume of inoperable byproducts
Solution Approach 1:
The patent inverts the conventional approach by moving the prelithiation function from the positive electrode to the negative electrode. Instead of adding complex reagents to the positive electrode that release lithium during cycling, the invention directly incorporates lithium-containing compounds into the negative electrode, which releases lithium ions during initial charging, eliminating the need for complex reagent synthesis and avoiding byproduct generation.
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 significantly improves the energy and cycle life of electrochemical cells by increasing the portion of reversible lithium ions, achieving a first cycle Coulombic efficiency of at least 60% and maintaining a second cycle capacity of at least 900 mAh/g, making it more practical for industrial-scale manufacturing.
Implementation Method 1
solid state pretreatment of active materials (e.g., prelithiation of silicon monoxide)
Implementation Method 2
The mixture is heated in an inert environment to form treated negative active material structures
Data Source
AI summary
Provided are methods for solid state pretreatment of active materials (e.g., prelithiation of silicon monoxide) while forming treated negative active material structures. Also provided are the formed structures, negative electrodes comprising these structures, and electrochemical cells comprising these electrodes. In some examples, silicon monoxide structures are mixed with lithium hydroxide structures or some other lithium-containing structures. The mixture is heated in an inert environment to form treated negative active material structures. These treated structures comprise various lithium-containing components, some of which trap lithium. When an electrochemical cell, formed with these treated negative active material structures, is initially charged and additional new lithium ions are introduced into the negative electrodes (e.g., from the positive electrode), a larger portion of these new lithium ions forms reversible components (rather than irreversible components) in the negative electrode than, for example, in a conventional cell without any such treatment.