All-Solid Sulfide Battery Cathode Structure for Stable Transfer Paths
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Solution Overview
Problem
Lithium secondary batteries with sulfur-based cathode materials face issues such as side reactions with polysulfides, disconnection of ion and electron transfer paths, and defects in the solid electrolyte layer leading to potential short circuits and reduced lifespan.
Innovation Solution
An all-solid secondary battery design featuring a lithium-containing sulfide-based cathode active material, a solid electrolyte layer, and a first inactive member to prevent side reactions, maintain ion and electron transfer paths, and reduce defects during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a sulfur-based material is used as cathode active material to increase capacity, then energy density is improved, but polysulfide side reactions occur that degrade lifespan
Solution Approach 1:
A lithium-containing sulfide-based material is introduced as an intermediary substance between the sulfur cathode and lithium anode. This intermediary material serves multiple functions: it buffers polysulfide side reactions, maintains structural stability during volume changes, and prevents direct contact between lithium metal and the electrolyte, thereby resolving the contradiction between high energy density and long lifespan
2Use of energy by moving object
If volume of sulfur-based material is increased during initial discharging, then capacity is improved, but transfer path of ions and electrons may be disconnected
Solution Approach 1:
The lithium-containing sulfide-based material forms a flexible buffer layer that can accommodate volume expansion of sulfur during discharge. This layer maintains continuous contact between electrode components during volume changes, preventing disconnection of ion and electron transfer paths while preserving high capacity
3Object-affected harmful factors
If solid electrolyte layer is used to improve safety, then fire and explosion risk is reduced, but defects and cracks may occur during manufacturing and charging/discharging
Solution Approach 1:
The lithium-containing sulfide-based material is placed beforehand as a protective buffer layer between the solid electrolyte and electrode components. This cushioning layer absorbs mechanical stress during manufacturing and charging/discharging cycles, preventing crack propagation and defect formation in the solid electrolyte, thereby maintaining safety while improving reliability
4Reliability
If lithium metal is used to grow through cracks in solid electrolyte, then short circuit risk increases, but this provides a mechanism to detect and prevent such failures
Solution Approach 1:
The lithium-containing sulfide-based material provides preliminary protection by filling and sealing potential crack pathways before lithium metal can grow through them. This preemptive action blocks the harmful propagation of lithium dendrites and prevents short circuits before they can occur
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 the battery's cycle characteristics, reduces the risk of short circuits, and improves energy density by maintaining stable ion and electron transfer paths and preventing side reactions.
Implementation Method 1
a solid electrolyte layer arranged between the cathode layer and the anode layer
Implementation Method 2
the cathode active material layer includes a lithium-containing sulfide-based cathode active material
Implementation Method 3
maintain ion and electron transfer paths
Implementation Method 4
a first inactive member arranged on a side of the cathode layer
Implementation Method 5
Lithium secondary batteries produce electrical energy through oxidation and reduction reactions if (e.g., when) lithium ions are intercalated/deintercalated into/from a cathode and/or an anode
Data Source
AI summary
An all-solid secondary battery including a cathode layer, an anode layer, and a solid electrolyte layer disposed between the cathode layer and the anode layer is provided. The cathode layer includes a cathode current collector and a cathode active material layer on one side or two sides (e.g., two (e.g., opposite) sides) of the cathode current collector, the cathode active material layer includes a lithium-containing sulfide-based cathode active material, the lithium-containing sulfide-based cathode active material includes Li2S and/or a Li2S-containing composite. The all-solid secondary battery includes a first inactive member disposed on a (e.g., one) side of the cathode layer, the anode layer includes an anode current collector and a first anode active material layer disposed on a (e.g., one) side of the anode current collector.