Multi-Layer Anode Structure for Bottom-Up Lithium Plating
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Solution Overview
Problem
Lithium metal batteries face challenges such as violent reactions with water, cycling stability issues due to volume changes and dendrite formation, and the need to confine lithium plating within a porous structure to reduce dendrite risk while maintaining energy density.
Innovation Solution
A multi-layer anode structure with varying exchange current densities for lithium plating, allowing for 'bottom-up' lithium plating from the current collector towards the separator, and pre-lithiation of the anode to incorporate lithium and reduce irreversible losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal anode is used to increase energy density, then specific capacity and redox potential are improved, but cycling stability deteriorates due to large volume changes during deposition and dissolution
Solution Approach 1:
The patent employs a porous anode structure where lithium metal is deposited within the porous framework. The porosity accommodates volume changes during lithium deposition and dissolution cycles, preventing structural degradation while maintaining high specific capacity. The porous material provides a three-dimensional host that absorbs expansion stress without compromising cycling stability.
2Use of energy by moving object
If lithium metal anode is used to increase energy density, then redox potential is improved, but cycling stability deteriorates due to dendrite formation
Solution Approach 1:
The porous structure distributes lithium deposition throughout the three-dimensional framework, preventing localized dendrite formation. The porous walls act as physical barriers that constrain lithium growth, while the distributed deposition pattern reduces current density hotspots that would otherwise promote dendritic growth.
Solution Approach 2:
The patent creates non-uniform lithium distribution within the porous structure, with preferential deposition in specific regions of the pore network. This controlled local deposition pattern, guided by the porous architecture, prevents the formation of protruding dendrites while maintaining overall uniformity across the electrode.
3Reliability
If porous structure is used to confine lithium plating and reduce dendrite risk, then cycling stability is improved, but weight increases reducing energy density advantages
Solution Approach 1:
The patent uses a porous structure with optimized porosity and wall thickness to achieve the minimum weight necessary for dendrite suppression. The porous framework provides just enough structural support to confine lithium plating while minimizing dead weight, balancing the trade-off between cycling stability and energy density.
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 multi-layer anode structure achieves uniform lithium plating, reduces the risk of dendrite formation, and enhances cycling stability by accommodating lithium deposition within the porous structure without causing significant volume changes.
Implementation Method 1
the cations are extracted from the cathode material and then diffuse from the cathode material through the electrolyte and intercalate into the anode material during charging
Implementation Method 2
lithium metal deposition and dissolution is associated with large volume changes which can reduce the cycling stability of the cell
Data Source
AI summary
The invention relates to a secondary cell comprising an anode, a cathode, optionally a separator, and an electrolyte, characterized in that the anode comprises particles in multiple layers.