Sulfur Cathode Mixture Solid Solution for Rate Property
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Solution Overview
Problem
Current sulfur-based cathode mixtures exhibit low rate properties when discharged at high rates due to insufficient ion conductivity, which is not effectively improved by adding Li3PO4, despite its low ion conductivity.
Innovation Solution
A cathode mixture comprising a solid solution of sulfur simple substance, P2S5, and Li3PO4 with a molar ratio of Li3PO4 to P2S5 between 0.05 and 0.67, along with a conductive auxiliary material, which enhances the rate property by facilitating Li intercalation and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li3PO4 is added to improve ion conductivity, then ion conductivity is improved, but rate property deteriorates due to insufficient ion conductivity
Solution Approach 1:
The invention creates a composite solid solution containing S, P2S5, and Li3PO4 in specific molar ratios. This composite structure combines the high capacity of sulfur with the ion conductivity enhancement from Li3PO4 and the rate property improvement from P2S5, achieving both improved ion conductivity and rate property simultaneously
Solution Approach 2:
The invention optimizes the molar ratios of components (Li3PO4:P2S5 = 0.05-0.67, S:P2S5 = 3-10) to achieve the desired balance between ion conductivity and rate property. By precisely controlling these compositional parameters, the solid solution exhibits both improved ion conductivity for reliability and good rate capability for productivity
2Quantity of substance
If sulfur simple substance is used as cathode active material, then theoretical capacity is improved to 1675 mAh/g, but rate property deteriorates due to low ion conductivity
Solution Approach 1:
The invention forms a composite solid solution where sulfur simple substance (S) is combined with P2S5 and Li3PO4. This composite structure maintains the high theoretical capacity of sulfur (1675 mAh/g) while the P2S5 and Li3PO4 components work together to improve ion conductivity and rate property, resolving the contradiction between capacity and rate capability
3Stability of the object's composition
If mechanical milling is conducted to produce cathode mixture, then mixing is improved, but rate property deteriorates due to insufficient ion conductivity
Solution Approach 1:
The invention creates a composite solid solution of S-P2S5-Li3PO4 that, when mechanically milled, produces a uniformly mixed cathode mixture with improved rate property. The specific molar ratios in the solid solution ensure that mechanical milling achieves both good mixing uniformity and enhanced rate capability, unlike conventional mixtures
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 cathode mixture demonstrates improved rate properties, achieving higher discharging capacity even at high discharge rates by optimizing the molar ratio of Li3PO4 to P2S5 and incorporating a conductive auxiliary material, thereby enhancing ion and electron conductivity.
Implementation Method 1
a solid solution of a sulfur simple substance, P2S5 and Li3PO4
Data Source
AI summary
A main object of the present disclosure is to provide a cathode mixture with good rate property. The present disclosure achieves the object by providing a cathode mixture comprising: a solid solution of a sulfur simple substance, P2S5 and Li3PO4, and a conductive auxiliary material, and a molar ratio of the Li3PO4 to the P2S5 is 0.05 or more and 0.67 or less.