Li-Sr Alloy Negative Electrode for Dendrite-Stable Li-S Batteries
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Solution Overview
Problem
Lithium-sulfur batteries suffer from poor life characteristics due to lithium dendrite formation and increased surface area, leading to decomposition of LiPS and lithium salt, which deteriorates battery performance.
Innovation Solution
A lithium secondary battery with a negative electrode comprising a Li-M alloy, where M is an alkaline earth metal, stabilizes lithium plating/dissolution, improving cell efficiency and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal negative electrode is used, then high energy density is achieved, but lithium dendrite formation occurs leading to poor life characteristics
Solution Approach 1:
The patent uses a Li-Sr alloy composite material for the negative electrode, combining lithium metal with strontium to form an intermetallic compound structure. This composite approach maintains the high energy density of lithium while the strontium component suppresses dendrite formation, resolving the contradiction between energy density and reliability.
Solution Approach 2:
The patent changes the physical and chemical parameters of the negative electrode material by forming specific intermetallic compounds (LiSr, Li2Sr) with controlled stoichiometric ratios. This parameter change in composition and structure prevents dendrite formation while maintaining electrochemical performance, thus improving life characteristics without sacrificing energy density.
2Area of moving object
If lithium dendrites and pores form, then surface area of negative electrode increases, but decomposition of LiPS and lithium salt accelerates
Solution Approach 1:
The patent converts the potential harm of increased surface area into a benefit by creating a controlled, uniform surface through the Li-Sr alloy structure. The strontium component creates a stable surface morphology that, while having increased area, prevents the harmful decomposition reactions by providing a more stable interface, thus turning the increased surface area from a harmful factor into a beneficial feature for capacity without the associated degradation.
3Duration of action of stationary object
If uniform plating/elution induction and interface stabilization are implemented, then lifespan is improved, but device complexity increases
Solution Approach 1:
The Li-Sr alloy negative electrode provides self-service by inherently stabilizing its own interface during electrochemical cycling. The intermetallic compound structure automatically maintains uniform lithium plating and elution without requiring additional external stabilization mechanisms, thus improving lifespan while avoiding increased device complexity.
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 Li-M alloy negative electrode enhances capacity retention and discharge capacity, suppressing LiPS and lithium salt decomposition, resulting in improved coulombic efficiency and extended battery life.
Implementation Method 1
uniform plating/elution induction of lithium
Implementation Method 2
stabilize plating/dissolution of the negative electrode
Implementation Method 3
interface stabilization are absolutely necessary
Implementation Method 4
suppressing LiPS and lithium salt decomposition
Data Source
Figure 1
AI summary
A negative electrode includes a lithium-alkaline earth metal alloy, and can be used in a lithium-sulfur battery. Furthermore, a method to obtain said negative electrode, and a lithium-sulfur battery containing the negative electrode.