Perforated Lithium Sheet for Rechargeable Battery
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Solution Overview
Problem
Conventional lithium-ion batteries face challenges in maintaining balance due to irreversible lithium consumption during the formation of the Solid Electrolyte Interphase (SEI) at the negative electrode, leading to reduced capacity and inefficiencies in lithium distribution and utilization.
Innovation Solution
A rechargeable lithium-ion battery design that incorporates a perforated lithium sheet with a specific thickness and pattern of perforations to provide the necessary lithium, calculated based on the capacitance of the SEI and active materials, allowing for optimal lithium balance without excess, enabling the use of active materials initially devoid of sufficient lithium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional lithium-ion battery design is used without additional lithium compensation, then the battery structure remains simple and manufacturing is easier, but the battery capacity decreases due to irreversible lithium consumption by SEI formation
Solution Approach 1:
The patent applies preliminary action by pre-calculating and adding a specific quantity of metallic lithium (Q2) to the cell before operation. This lithium is specifically intended to compensate for the irreversible consumption by SEI formation, ensuring that sufficient active lithium remains available for reversible cycling from the outset.
Solution Approach 2:
The patent changes the lithium quantity parameter by introducing a calculated amount of metallic lithium (Q2) in addition to the lithium initially present in the positive electrode active material (Q1). This parameter adjustment ensures the total lithium quantity meets the requirements for both SEI formation and reversible capacity.
2Quantity of substance
If metallic lithium is added to compensate for SEI lithium consumption, then the lithium balance is restored and capacity is improved, but the cell construction becomes more complex and requires removal of auxiliary electrodes
Solution Approach 1:
The patent merges the lithium compensation function with the existing electrode structure by integrating metallic lithium directly into the cell assembly. This eliminates the need for separate auxiliary electrodes, combining multiple functions (lithium source, electrode component) into a unified structure that simplifies construction.
Solution Approach 2:
The patent extracts the lithium compensation requirement from the complex auxiliary electrode system and implements it through direct metallic lithium addition. This removes the need for separate compensation mechanisms, simplifying the overall cell construction while maintaining lithium balance.
3Reliability
If lithium powder with protective coating is used to compensate for lithium loss, then the reactivity is controlled, but unwanted elements remain in the final battery and capacity is reduced
Solution Approach 1:
The patent uses pure metallic lithium that can be fully utilized for its intended purpose (lithium compensation and reversible cycling) without requiring protective coatings. This disposable-like approach ensures complete lithium utilization, avoiding the capacity loss associated with coating materials remaining in the final battery.
4Quantity of substance
If pre-lithiation is performed outside the electrochemical cell, then the negative electrode is pre-balanced, but additional processing steps and electrolyte washing are required
Solution Approach 1:
The patent merges the pre-lithiation process with the cell assembly process itself. By adding metallic lithium during cell construction rather than performing separate pre-lithiation outside the cell, the patent eliminates additional processing steps and electrolyte washing operations, thereby improving manufacturing efficiency while achieving the same lithium balance objective.
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 design ensures a balanced electrochemical cell with sufficient lithium after the first cycle, ensuring optimal operation and allowing the use of lithium-poor or lithium-free active materials, enhancing the battery's performance and efficiency over multiple cycles.
Implementation Method 1
a solid electrolyte interphase (SEI) passivation layer is capable of forming on the surface of the negative electrode
Implementation Method 2
some of the active lithium initially contained in the positive electrode is irreversibly consumed during the initial insertion into the negative electrode material
Implementation Method 3
lithium ions are disintercalated by oxidation of the positive electrode, and migrate through the electrolyte, an ionically conductive material, to the negative electrode
Implementation Method 4
lithium ions are disintercalated by oxidation of the positive electrode
Implementation Method 5
the negative electrode, usually based on a carbon-based material, which is reduced with the intercalation of these ions
Implementation Method 6
a lithium-ion battery is an electrochemical generator that uses lithium in its ionic form. It releases electricity through the reversible exchange of lithium ions between a positive and a negative electrode
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention relates to an electrochemical cell (1) of rechargeable lithium-ion battery, comprising a positive electrode (2) comprising a first active material possibly initially containing an amount Q1 of active lithium, a negative electrode (4) comprising a second active material and on the surface of which a SEI passivation layer is capable of forming, and an electrolyte for lithium ions.The positive electrode (2) comprises, opposite the negative electrode (4), a perforated lithium foil (8) having a thickness and pattern of perforations chosen to constitute a quantity Q2 of lithium, the quantity Q2 of lithium supplied by the perforated lithium foil (8) and the quantity Q1 of active lithium supplied by the first active material of the positive electrode (2) when said first active material initially comprises active lithium, constituting the quantity of lithium necessary and sufficient for the equilibrium of the electrochemical cell (1).