All-solid-state battery electrode area design
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Solution Overview
Problem
Current lithium ion batteries using organic electrolytes are combustible, leading to safety concerns and limitations in energy density, manufacturing costs, and productivity, while all-solid-state batteries with organic solid electrolytes face challenges in ion conductivity and reliability due to metallic lithium growth.
Innovation Solution
An all-solid-state battery design with a solid electrolyte layer positioned between the positive and negative electrode layers, where the negative electrode mixture layer has a larger area than the positive electrode mixture layer, and specific thickness and protrusion structures to suppress metallic lithium precipitation on the current collector, enhancing reliability and charge-discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic electrolyte is used in lithium ion battery, then high ion conductivity is achieved, but combustibility and safety issues occur
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid to solid, and transitions from organic to inorganic materials. This fundamental parameter change eliminates combustibility while maintaining ion conductivity through selection of inorganic solid electrolyte materials such as oxides or sulfides.
Solution Approach 2:
The patent replaces the hazardous organic electrolyte with inorganic solid electrolyte materials that are inherently safer and non-combustible. This substitution eliminates the safety hazards associated with organic electrolytes while providing a more stable and reliable battery system.
2Reliability
If organic solid electrolyte is used in all-solid-state battery, then safety is improved, but ion conductivity is too low for operation at 25°C
Solution Approach 1:
The patent changes the material composition from organic solid electrolyte to inorganic solid electrolyte. This parameter change dramatically increases ion conductivity from 10^-6 S/cm to 10^-4 to 10^-3 S/cm, enabling operation at room temperature while maintaining the safety advantages of solid electrolytes.
Solution Approach 2:
The patent employs inorganic solid electrolyte materials such as oxide solid electrolytes or sulfide solid electrolytes, which combine the safety benefits of solid electrolytes with high ion conductivity. These composite inorganic materials enable both safety and performance requirements to be met simultaneously.
3Object-generated harmful factors
If oxide solid electrolyte is used, then high ion conductivity is achieved, but grain boundary resistivity is high requiring thinning
Solution Approach 1:
The patent changes the material type from oxide solid electrolyte to sulfide solid electrolyte. This parameter change fundamentally alters the electrical properties, reducing grain boundary resistivity from high levels to low levels, thereby eliminating the need for thinning operations while maintaining high ion conductivity.
Solution Approach 2:
The patent selects sulfide solid electrolyte materials that inherently possess low grain boundary resistivity, eliminating the need for additional processing steps such as thinning. This material selection simplifies the device structure and manufacturing process while achieving the desired electrical performance.
4Quantity of substance
If metallic lithium grows on negative electrode layer, then charge-discharge capacity increases, but reliability decreases due to movement to positive electrode
Solution Approach 1:
The patent introduces a solid electrolyte layer as an intermediary barrier between the negative electrode where lithium grows and the positive electrode. This intermediary layer prevents direct contact and movement of metallic lithium, eliminating the reliability issues while allowing lithium ion capacity to be maintained through proper material selection.
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 design effectively suppresses metallic lithium precipitation, improving the reliability and charge-discharge characteristics of the battery, stabilizing charge and discharge processes, and reducing manufacturing costs by using a solid electrolyte with higher ion conductivity.
Implementation Method 1
The solid electrolyte layer includes a solid electrolyte having ion conductivity and is disposed between the positive electrode mixture layer and the negative electrode mixture layer
Data Source
AI summary
An all-solid-state battery includes: a positive electrode layer including a positive electrode current collector and a positive electrode mixture layer; a negative electrode layer including a negative electrode current collector and a negative electrode mixture layer; and a solid electrolyte layer. The solid electrolyte layer is disposed between the positive electrode mixture layer and the negative electrode mixture layer. On a plane perpendicular to a stacking axis, an area of the negative electrode mixture layer is larger than an area of the positive electrode mixture layer. On the stacking axis, an entire portion of the positive electrode mixture layer overlaps a portion of the negative electrode mixture layer.