Lithium Anode Grid Structure for Volume Expansion Management
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Solution Overview
Problem
Lithium-ion batteries face challenges with volume changes in the anode during lithium ion storage and release, leading to mechanical stress and reduced cycle stability, as well as issues with prelithiation causing volume effects in cathode materials.
Innovation Solution
A lithium anode with a grid-like current collector layer, anode active material such as silicon, and a coating of lithium-conductive material like graphite, where the anode active material is arranged in cavities of the conductor structure to allow for volume expansion without global volume change, and a cathode arrangement with a grid-like conductor structure and lithium-based material in cavities for prelithiation, minimizing volume changes and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If anode active material is used to increase lithium ion capacity, then the theoretical capacity of lithium cells is improved, but volume changes during lithium ion storage and release cause mechanical stress and reduced cycle stability
Solution Approach 1:
The anode is segmented into multiple cavities that can independently accommodate volume changes of anode active material during lithium ion storage and release. Each cavity acts as an independent unit that can expand and contract locally without affecting the overall structural integrity of the anode, thereby maintaining cycle stability while utilizing high-capacity materials.
Solution Approach 2:
The patent applies different structural qualities to different regions: the cavities provide local flexibility to accommodate volume expansion, while the current collector layer provides global structural support. This local differentiation allows the anode to simultaneously achieve high lithium ion capacity and maintain structural stability during cycling.
2Quantity of substance
If high-capacity anode active materials are used, then energy density is improved, but mechanical stress from volume changes leads to detachment and bursting of protective layers
Solution Approach 1:
The cavity structure serves as a pre-designed cushioning space that anticipates and accommodates the volume expansion of anode active material during lithium ion storage. This beforehand cushioning prevents mechanical stress from transferring to the protective coating, eliminating the risk of detachment and bursting while enabling the use of high-capacity materials that increase energy density.
3Strength
If the anode structure is made rigid to maintain structural integrity, then mechanical strength is improved, but volume expansion during lithium ion storage is restricted
Solution Approach 1:
The anode is divided into multiple independent cavities that can expand and contract independently. This segmentation allows the structure to maintain overall rigidity and structural integrity through the current collector layer while permitting local volume expansion within each cavity during lithium ion storage, thus resolving the contradiction between structural strength and volume flexibility.
4Strength
If protective layers are added to prevent mechanical impairment, then adhesion is improved, but ion conduction is blocked
Solution Approach 1:
The protective coating is designed with porous characteristics that allow lithium ion conduction while providing mechanical protection. The porous structure enables ions to pass through the coating to reach the anode active material, maintaining reliable ion conduction while the coating still provides adhesion and prevents mechanical impairment of the underlying structure.
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 ensures minimal global volume change in the anode, improved mechanical stability, and increased cycle life by allowing local volume expansion within the anode and compensating for lithium loss during SEI formation, thereby enhancing the energy density and stability of lithium-ion cells.
Implementation Method 1
a coating (6), in particular of a lithium-conductive material, for example graphite
Implementation Method 2
volume changes in the anode during lithium ion storage and release, leading to mechanical stress
Data Source
Figure 1~4
Figure 5~8
Figure 9
AI summary
The present invention relates to a lithium anode (1) for a lithium cell (200) and/or lithium battery (200), comprising: a current collector layer (4), an anode active material (5), and a coating (6), wherein the current collector layer (4) is designed in a grid-like manner with a conductor structure (2) defining open cavities (3), the anode active material (5) is arranged as a layer on the surface of the conductor structure (2), and the coating (6) covers the current collector layer (4) and thus the anode active material (5), and a filling is provided to fill the cavities (3), which is coupled to the anode active material (5) and the coating (6). The invention also relates to a method for producing such a lithium anode.