Sulfide Glass Coated Lithium Negative Electrode for Dendrite Prevention
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Solution Overview
Problem
Lithium secondary batteries face challenges with graphite negative electrodes due to limited capacity and dendrite precipitation, while lithium metal electrodes suffer from internal short circuits and low reliability, and alternative materials like tin and silicon experience volume expansion issues, leading to cycle deterioration and reduced capacity.
Innovation Solution
A negative electrode material comprising sulfur and sulfide glass with specific elemental ratios, providing water-resistant properties and high capacity retention, and a composite powder structure with sulfide glass coating to enhance ionic conductivity and prevent dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as negative electrode material, then high theoretical capacity is achieved, but dendrites precipitate causing internal short circuit and low reliability
Solution Approach 1:
The patent uses a composite structure where lithium metal is combined with a solid electrolyte layer containing sulfide glass and specific additives (Bi, Pb, Zn, Al, or Ga). This composite approach allows the lithium metal to provide high capacity while the solid electrolyte layer prevents dendrite formation and internal short circuits, resolving the contradiction between capacity and reliability.
2Reliability
If graphite is used as negative electrode material, then reliability is improved with no internal short circuit, but theoretical capacity is limited to 372 mAh/g
Solution Approach 1:
The patent creates a composite negative electrode by combining lithium metal (high capacity) with a solid electrolyte layer containing sulfide glass and specific metal elements. This composite structure provides both the high theoretical capacity of lithium metal (3860 mAh/g) and the reliability of preventing internal short circuits, overcoming the capacity limitation of graphite while maintaining safety.
3Quantity of substance
If tin or silicon is used as negative electrode material, then high lithium absorption capacity is achieved, but volume expansion up to four times causes electrode disintegration and cycle deterioration
Solution Approach 1:
The patent employs a composite structure where the active material (tin, silicon, or their alloys) is combined with a solid electrolyte layer containing sulfide glass and specific metal elements (Bi, Pb, Zn, Al, or Ga). This composite approach allows the active material to provide high lithium absorption capacity while the solid electrolyte layer constrains volume expansion and prevents electrode disintegration, maintaining structural stability during cycling.
4Quantity of substance
If Sn film layer is thickened to achieve capacity per unit area of 1.5 mAh/cm2 or more, then initial capacity is increased, but cycle deterioration increases and input-output characteristics are reduced
Solution Approach 1:
The patent changes the physical and chemical parameters of the solid electrolyte layer by incorporating specific metal elements (Bi, Pb, Zn, Al, or Ga) into the sulfide glass matrix. This parameter modification enables the solid electrolyte layer to effectively constrain volume expansion even at optimal thicknesses, achieving both high initial capacity (1.5 mAh/cm2 or more) and excellent cycle characteristics without the trade-off observed in conventional thick Sn film electrodes.
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 achieves excellent cycle life and high output performance with no dendrite precipitation at low temperatures, maintaining high discharge capacity and reducing manufacturing costs through the use of water-based binders and improved handling of sulfide glass.
Implementation Method 1
sulfide glass including the following components (i) and (ii)... provides water-resistant properties and high capacity retention... enhance ionic conductivity
Implementation Method 2
elements such as tin and silicon can increase their volume up to about four times as a result of lithium absorption and release... sulfide glass coating to enhance ionic conductivity and prevent dendrite formation
Implementation Method 3
providing water-resistant properties and high capacity retention... no dendrite precipitation at low temperatures
Data Source
AI summary
[Object] The object is to provide a negative electrode material for a lithium secondary battery, wherein a sulfide-based negative electrode with water-resistant properties can exert excellent cycle characteristics and high output performance while maintaining a high discharge capacity and there is no precipitation of lithium dendrites during charge at low temperature.[Means for Solving Problems] A negative electrode material for a lithium secondary battery comprising sulfur and sulfide glass including the following components (i) and (ii):(i) at least one or more elements selected from a group consisting of Sb, As, Bi, Ge, Si, Cu, Zn, Pd, In and Zr; and(ii) at least one or more elements selected from a group consisting of Se, Te, Ga, Sn, Pb, Cd, Al, Fe, Mg, Ca, Co, Ag, Sr, P and Ba,wherein the ratio of the above components is sulfur: 40-80 mol %, (i): 1-50 mol % and (ii): 1-50 mol %, respectively.