Lattice Polymer Anode Structure for Lithium Dendrite Suppression
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Solution Overview
Problem
Lithium metal secondary batteries face issues with dendrite formation, severe volume changes, and low mechanical strength, leading to reduced cycle life and energy density, especially in medium- and large-sized batteries.
Innovation Solution
A negative electrode comprising a porous polymer substrate with a lattice structure and filled with lithium metal or alloy, providing mechanical support and uniform deposition, and a free-standing design without a current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as negative electrode material to achieve high theoretical capacity (>3800 mAh/g), then energy density is improved, but dendrite formation and volume expansion occur leading to reduced reliability
Solution Approach 1:
The patent employs a porous polymer substrate with a three-dimensional network structure containing numerous pores. These pores accommodate lithium metal deposits during charging cycles, preventing dendrite formation and volume expansion. The porous structure allows lithium to be stored uniformly throughout the substrate volume rather than forming irregular dendritic growth on the surface, thereby maintaining both high capacity and reliability.
Solution Approach 2:
The patent creates a composite structure combining lithium metal with a porous polymer substrate. This composite approach integrates the high capacity advantage of lithium metal with the structural stability and dendrite-suppressing properties of the polymer matrix. The composite material maintains mechanical integrity while enabling reversible lithium storage, resolving the contradiction between capacity and reliability.
2Quantity of substance
If lithium metal negative electrode is used to achieve high energy density, then capacity is improved, but severe volume changes during charge-discharge cycles occur leading to performance degradation
Solution Approach 1:
The porous polymer substrate provides a three-dimensional network with numerous pores that accommodate lithium metal deposits during charging. This porous structure absorbs and distributes the volume changes throughout its framework, preventing severe localized expansion and contraction. The substrate's open structure allows the lithium to be stored uniformly, maintaining volume stability while preserving high capacity.
3Weight of moving object
If lithium metal is used as free-standing negative electrode without current collector to maximize energy density, then weight is reduced, but mechanical strength is insufficient causing manufacturing defects
Solution Approach 1:
The patent uses a porous polymer substrate that functions as a flexible, mechanically robust framework. This substrate provides the necessary mechanical strength for handling and manufacturing while remaining lightweight. The polymer film structure serves as both the structural support and the active lithium storage medium, eliminating the need for heavy current collectors while maintaining sufficient mechanical integrity.
Solution Approach 2:
The composite of lithium metal and porous polymer substrate creates a material with enhanced mechanical properties. The polymer matrix provides structural framework and mechanical strength, while the lithium metal fills the pores to provide electrochemical function. This composite structure achieves both low weight and sufficient mechanical strength for manufacturing.
4Quantity of substance
If lithium metal negative electrode is used to achieve high capacity, then energy density is improved, but irregular dendrite morphology causes short circuits leading to reduced safety
Solution Approach 1:
The porous polymer substrate with its three-dimensional network structure provides numerous nucleation sites for lithium deposition throughout the bulk volume. This distributes the lithium storage function throughout the substrate rather than allowing dendrites to grow irregularly on the surface. The uniform pore distribution prevents localized dendritic growth that could penetrate the separator and cause short circuits, while maintaining high capacity.
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 enhances mechanical strength, suppresses dendrite growth, and improves energy density and manufacturing efficiency, resulting in improved cycle life and Coulombic efficiency.
Implementation Method 1
the porous polymer substrate has a lattice structure including a line portion and an open portion, wherein each open portion of the porous polymer substrate is filled with the negative electrode active material in whole or in at least part
Implementation Method 2
the ionic form of lithium released from the positive electrode is changed to neutral lithium through electrochemical reaction with electrons from an external conductor, to form very irregular lithium deposits in dendrite shape on the lithium surface during charging
Data Source
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AI summary
A negative electrode for a secondary battery according to the present disclosure includes a porous polymer substrate and a negative electrode active material loaded into the porous polymer substrate, wherein the porous polymer substrate has a lattice structure including a line portion and an open portion, wherein each open portion of the porous polymer substrate is filled with the negative electrode active material in whole or in at least part, and wherein the negative electrode active material includes at least one of a lithium metal or a lithium alloy. The negative electrode for the secondary battery including the porous polymer substrate of the lattice structure may have high mechanical strength, and suppress dendrite formation on the negative electrode and volume expansion of the negative electrode during charging and discharging.