Lithium-Lanthanum Alloy Anode for Dendrite-Stable Li-S Batteries
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Solution Overview
Problem
Lithium-sulfur batteries face challenges with the instability of lithium metal negative electrodes, leading to issues like lithium dendrite formation, internal short circuits, and reduced battery capacity and cycle lifetime.
Innovation Solution
The use of a lithium-lanthanum alloy negative electrode in lithium-sulfur batteries stabilizes the plating and dissolution of lithium, improving cell efficiency and lifespan by suppressing lithium polysulfide and lithium salt decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as the negative electrode active material to achieve high capacity and high energy density, then the theoretical specific capacity reaches 3,860 mAh/g and standard reduction potential is -3.045 V, but the electrochemical reaction continuously occurs on the surface of lithium metal causing the solid electrolyte interface layer to be unstable and leading to lithium dendrite formation
Solution Approach 1:
The patent changes the chemical composition parameter of the negative electrode from pure lithium metal to lithium-lanthanum alloy, specifically controlling the lanthanum content at 1-10 wt%. This compositional parameter change modifies the surface properties and electrochemical behavior, leading to more stable solid electrolyte interface layer formation while maintaining high capacity close to the theoretical 3,860 mAh/g of lithium metal.
Solution Approach 2:
The patent creates a composite negative electrode material by alloying lithium with lanthanum metal. This composite structure combines the high capacity advantage of lithium metal with the stability benefits of lanthanum, which has lower reactivity with electrolytes. The composite lithium-lanthanum alloy forms a more stable and uniform solid electrolyte interface layer, preventing lithium dendrite formation while maintaining high theoretical specific capacity.
2Reliability
If the solid electrolyte interface layer is formed on lithium metal surface to suppress direct reaction between electrolyte and lithium metal, then stability is improved, but the layer is weak in mechanical strength causing structure collapse during charging/discharging and forming lithium dendrite
Solution Approach 1:
The patent changes the mechanical and chemical parameters of the negative electrode material by introducing lanthanum alloying. This parameter change results in a solid electrolyte interface layer with improved mechanical strength and adhesion properties. The lithium-lanthanum alloy surface forms an interface layer that maintains structural integrity during volume changes associated with charging and discharging, preventing the collapse that leads to dendrite formation.
Solution Approach 2:
The composite lithium-lanthanum alloy structure creates a solid electrolyte interface layer with enhanced mechanical properties. The lanthanum component contributes to forming a more robust and flexible interface layer that can accommodate the expansion and contraction of lithium during electrochemical cycling without collapsing, thereby maintaining structural stability and preventing dendrite formation.
3Quantity of substance
If lithium dendrite is formed on the surface of lithium metal due to local difference in current density, then internal short circuit and inert lithium occur, but this reduces battery capacity and cycle lifetime
Solution Approach 1:
The patent changes the surface electrochemical parameters of the negative electrode by using lithium-lanthanum alloy instead of pure lithium metal. This parameter change leads to more uniform current density distribution during electrochemical reactions, preventing the localized high current density that causes lithium dendrite nucleation and growth. The alloy composition controls the plating behavior to avoid dendrite formation, thereby preserving battery capacity and extending cycle lifetime.
Solution Approach 2:
The composite lithium-lanthanum alloy material inherently suppresses lithium dendrite formation through its alloyed structure. The lanthanum atoms modify the surface morphology and electrochemical properties, creating a more uniform lithium deposition pattern during charging. This composite structure prevents the formation of protrusions that would concentrate current and initiate dendrite growth, thus eliminating the harmful effects of internal short circuits and inert lithium while maintaining high battery 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 lithium-lanthanum alloy negative electrode enhances the cycle characteristics and coulombic efficiency of lithium-sulfur batteries, effectively preventing lithium dendrite growth and maintaining battery stability during charging and discharging.
Implementation Method 1
the electrochemical reaction of the battery continuously occurs on the surface of lithium metal
Implementation Method 2
a solid electrolyte interface layer (SEI layer), which is a kind of passivation layer, is formed on the surface of the negative electrode
Data Source
Figure 1
Figure 2~3
AI summary
Disclosed is a negative electrode including a lithium-lanthanum alloy, and the negative electrode can be applied to a negative electrode for a lithium-sulfur battery. The lithium-sulfur battery to which the alloy negative electrode is applied has improved life characteristics and improved electrochemical efficiency.