Layered Lithium Anode Sheet for Dendrite-Resistant Cycling
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Solution Overview
Problem
The direct contact between metallic lithium and liquid electrolyte in lithium metal batteries leads to issues such as lithium dendrite growth, continuous thickening of the solid electrolyte interface (SEI) film, formation of dead lithium, and penetration of the separator, hindering the large-scale application of lithium metal batteries.
Innovation Solution
An anode electrode sheet is designed with a first active material layer of metallic lithium and a second active material layer of a metallic lithium alloy, preventing direct contact with the electrolyte and enabling an alloying reaction to avoid lithium dendrite growth and SEI film thickening, while a bipolar electrode sheet uses a metallic lithium alloy and a positive electrode active material to enhance cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metallic lithium is used as the negative electrode active material to achieve ultra-high specific capacity, then the energy density of the battery is improved, but lithium dendrite growth and separator penetration occur
Solution Approach 1:
The negative electrode is divided into multiple layers: a first active material layer containing metallic lithium, a second active material layer containing lithium alloy, and optionally a third active material layer containing lithium alloy or metallic lithium. This segmentation allows the highly reactive metallic lithium to be isolated from direct contact with the electrolyte while still providing high capacity, thereby resolving the contradiction between energy density and cycle stability.
Solution Approach 2:
The lithium alloy layer acts as an intermediary between the metallic lithium layer and the electrolyte. It buffers the volume expansion of metallic lithium during cycling and prevents direct contact between metallic lithium and the electrolyte, thus eliminating lithium dendrite growth while preserving the high capacity benefits of metallic lithium.
2Ease of operation
If metallic lithium directly contacts the liquid electrolyte to enable lithium ion transport, then the battery can operate, but continuous SEI film thickening and dead lithium formation occur
Solution Approach 1:
The lithium alloy layer is placed in advance between the metallic lithium and the electrolyte to perform preliminary protection. This layer forms a stable interface with the electrolyte before metallic lithium can directly contact it, preventing continuous SEI formation and lithium loss while still allowing lithium ion transport for battery operation.
3Reliability
If a protective layer is added to prevent lithium dendrite growth, then cycle stability is improved, but the device structure becomes more complex
Solution Approach 1:
The protective function is merged into the electrode structure itself by using lithium alloy materials that inherently buffer volume expansion and prevent dendrite growth. This integrates the protective function into the active material layers rather than adding separate protective components, thereby improving cycle stability without significantly increasing structural complexity.
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 effectively prevents lithium dendrite growth and SEI film thickening, improving the cycle stability and safety of lithium metal batteries by using a layered structure with metallic lithium and its alloy.
Implementation Method 1
it may enable an alloying reaction between the metallic lithium and the metallic lithium alloy in the second active material layer during the charge and discharge process of the battery
Data Source
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AI summary
Disclosed are an anode electrode sheet and a preparation method therefor, a bipolar electrode sheet and a preparation method therefor, a battery and an electric device. The anode electrode sheet comprises: a first current collector comprising a first side and a second side opposite to each other; a first active material layer and a second active material layer, wherein the first active material layer and the second active material layer are sequentially disposed on the first side in a direction away from the first current collector, the first active material layer comprises metallic lithium, and the second active material layer comprises a metallic lithium alloy. The use of this anode electrode sheet or bipolar electrode sheet may avoid problems such as continuous thickening of the SEI film, persistent growth of lithium dendrites, formation of dead lithium, and penetration of the separator by lithium dendrites, thereby helping to improve the cycle stability of the battery using the anode electrode sheet or bipolar electrode sheet.