Lithium Anode Intermediate Layer for Crack Prevention
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Solution Overview
Problem
Current lithium anodes in lithium-ion batteries experience non-uniform lithium deposition, leading to increased porosity and volume changes, which cause stress and cracking in protective layers, impairing their functionality over charge/discharge cycles.
Innovation Solution
A lithium electrode design featuring a first lithium layer with an intermediate layer that acts as a stabilizing support matrix between the lithium layer and a lithium-ion conductive protective layer, where the intermediate layer has electrical conductivity less than 10^-10 S/cm and is preferably porous or contains continuous openings to facilitate lithium ion transport and mechanical support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is applied to prevent lithium deposition and electrolyte contact, then protection function is improved, but the protective layer cracks due to volume movements of lithium anode
Solution Approach 1:
An intermediate layer is introduced between the lithium anode and the protective layer. This intermediate layer acts as a buffer that absorbs volume changes of the lithium anode during charge/discharge cycles, preventing stress transmission to the protective layer. The intermediate layer has lithium ion conductivity to maintain ion transport while providing mechanical compliance to accommodate lithium volume expansion and contraction.
Solution Approach 2:
The intermediate layer is designed with specific physical and chemical parameters: it has lithium ion conductivity (unlike the outer protective layer), appropriate mechanical compliance to match lithium volume changes, and chemical stability. By changing the conductivity parameter from the traditional single-layer approach (where the protective layer was both protective and ion-conductive), the system can now differentiate between ion transport function and mechanical protection function.
2Use of energy by moving object
If lithium metal is used as anode, then battery energy density is improved, but non-uniform lithium deposition occurs causing porosity increase
Solution Approach 1:
The intermediate layer serves as a mediator between the lithium metal anode and the protective layer, providing a stable interface that accommodates lithium volume changes. This layer maintains structural stability during lithium deposition and dissolution cycles, preventing the formation of large pores and maintaining intimate contact between the lithium anode and protective layer throughout battery operation.
3Reliability
If protective layer constantly moves with lithium surface, then continuous protection is maintained, but ion-conducting materials cannot withstand volume movements over cycles
Solution Approach 1:
The intermediate layer acts as a compliant intermediary that moves with the lithium surface during volume changes, while the outer protective layer remains relatively stable. This decoupling allows the protective layer to maintain continuous protection without experiencing the damaging cyclic stress that would otherwise cause cracking and failure over time.
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 intermediate layer absorbs mechanical stresses during volume changes, preventing damage to the protective layer and ensuring long-term protection of the lithium anode, thereby enhancing the service life of lithium-ion batteries.
Implementation Method 1
The intermediate layer acts as a stabilizing support matrix on the surface of the lithium layer. This matrix has the task of mechanically supporting the protective layer applied to the lithium in such a way that no stresses are transferred to the brittle protective layer as a result of volume movements of the first lithium layer.
Implementation Method 2
a lithium-ion-conductive protective layer arranged on a second side of the first lithium layer, opposite the first side
Implementation Method 3
it is preferred that the intermediate layer does not consist of a solid material throughout, but rather has pores and/or openings. Particularly preferably, at least percent by volume of the intermediate layer consists of pores and/or openings.
Data Source
Figure 1~3a
Figure 3b~3d
Figure 3e~4b
AI summary
The invention relates to a lithium electrode. Said electrode comprises a first lithium layer (22), which consists of lithium or a lithium alloy, a current collector (21) arranged on a first side of the first lithium layer, and a lithium-ion-conducting protective layer (23) arranged on a second side of the first lithium layer, opposite the first side. Between the first lithium layer (22) and the protective layer (23) there is an intermediate layer (24) which completely covers the second side of the first lithium layer (22). Both the protective layer (23) and the intermediate layer (24) each have an electrical conductivity of less than 10-10 S/cm. The lithium electrode can be used as the anode of a lithium-ion battery. For the production thereof, a first lithium layer (22), which consists of lithium or a lithium alloy, is applied to a current collector (21), an intermediate layer (24) having an electrical conductivity of less than 10-10 S/cm is applied to the first lithium layer (22) in such a way that the intermediate layer (24) completely covers the first lithium layer (22), and a lithium-ion-conducting protective layer (23) having an electrical conductivity of less than 10-10 S/cm is applied to the intermediate layer (24).