Layered Lithium Anode Sheet With Artificial SEI for Dendrite Control
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Solution Overview
Problem
Lithium metal anode electrodes in batteries face issues such as continuous thickening of the SEI film, persistent growth of lithium dendrites, and penetration of the separator by lithium dendrites, leading to reduced cycle stability.
Innovation Solution
An anode electrode sheet with a layered structure comprising a current collector, a first active material layer of metallic lithium, a second active material layer of a metallic lithium alloy, and a first artificial SEI layer of lithide, which prevents direct contact of highly reactive metallic lithium with the electrolyte and facilitates alloying reactions for uniform deposition, thereby preventing lithium dendrite growth and SEI film thickening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metallic lithium is used as the anode electrode active material to achieve ultra-high theoretical specific capacity, then the energy density of the battery is enhanced, but the high chemical reactivity of metallic lithium causes continuous thickening of the SEI film and growth of lithium dendrites
Solution Approach 1:
The patent divides the anode electrode into multiple functional layers: a first active material layer containing metallic lithium, a second active material layer containing a metallic lithium alloy, and a first artificial SEI layer containing a lithide. This segmentation allows each layer to perform its specific function - the metallic lithium provides high capacity, the alloy layer buffers volume expansion, and the artificial SEI layer prevents harmful reactions with the electrolyte, thereby resolving the contradiction between high energy density and cycle stability
Solution Approach 2:
The patent applies a preliminary protective action by forming an artificial SEI layer containing a lithide on the anode electrode structure before the battery operates. This pre-formed protective layer prevents direct contact between the highly reactive metallic lithium and the electrolyte, avoiding continuous SEI film thickening and dendrite growth, thus ensuring long-term cycle stability while maintaining the high energy density benefit of metallic lithium
2Quantity of substance
If metallic lithium is used as the anode electrode, then the theoretical specific capacity reaches 3860 mAh/g, but the high diffusion barrier of lithium ions causes them to react with the electrolytic solution, consuming the metallic lithium and electrolyte
Solution Approach 1:
The patent introduces an intermediary substance - a lithide-containing artificial SEI layer - that acts as a protective barrier between the metallic lithium and the electrolyte. This intermediary layer allows lithium ion transport while preventing direct harmful reactions, thereby maintaining the high theoretical specific capacity of metallic lithium while significantly reducing the consumption of both lithium and electrolyte during battery operation
3Quantity of substance
If metallic lithium anode electrodes are used, then the volume expansion rate is infinitely large, but this causes continuous thickening of the SEI film and formation of dead lithium
Solution Approach 1:
The patent employs composite material design by combining metallic lithium with a metallic lithium alloy in a layered structure. The alloy component provides structural stability and buffers the infinitely large volume expansion of pure metallic lithium during lithiation and delithiation cycles. This composite approach maintains the high lithium capacity while achieving volume stability, preventing continuous SEI film thickening and dead lithium formation
4Use of energy by moving object
If metallic lithium is used in the anode electrode, then the energy density is enhanced, but lithium dendrites grow and penetrate the separator
Solution Approach 1:
The patent segments the anode structure into multiple layers with different functions, including an artificial SEI layer that acts as a physical barrier to dendrite growth. This segmentation prevents dendrites from reaching the separator while maintaining the high energy density benefit of metallic lithium in the first active material layer
Solution Approach 2:
The patent applies preliminary protective measures by forming an artificial SEI layer containing a lithide before battery operation. This pre-formed protective barrier prevents the initiation and growth of lithium dendrites that would otherwise penetrate the separator, ensuring safety while maintaining the high energy density of metallic lithium
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 layered structure enhances the cycle stability of lithium metal batteries by preventing lithium dendrite growth and SEI film thickening, improving the battery's performance and longevity.
Implementation Method 1
allow an alloying reaction to occur between the metallic lithium and the metallic lithium alloy in the second active material layer during the charge and discharge processes of the battery
Implementation Method 2
promote the rapid migration of lithium ions, thereby effectively preventing the growth of lithium dendrites
Data Source
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AI summary
Disclosed are an anode electrode sheet, a preparation method therefor and use thereof. The anode electrode sheet includes: a current collector having a first side and a second side opposite to each other; a first active material layer, a second active material layer, and a first artificial SEI layer, the first active material layer, the second active material layer, and the first artificial SEI layer are sequentially arranged on the first side of the current collector in a direction away from the current collector, the first active material layer includes metallic lithium, the second active material layer includes a metallic lithium alloy, and the first artificial SEI layer includes a lithide. The use of this anode electrode sheet can avoid the problems such as continuous thickening of the SEI film, persistent growth of lithium dendrites, dead lithium, and penetration of the separator by lithium dendrites, etc., thereby being conducive to improving the cycle stability of a lithium metal battery employing such an anode electrode sheet.