Solid Lithium Battery Anode Current Collector Roughness Control
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Solution Overview
Problem
Solid lithium secondary batteries with a pressed powder type solid electrolyte layer face a high risk of short-circuit due to dendrite formation, which can occur when the surface roughness of the anode current collector is either too small or too large, leading to uneven contact and current concentration.
Innovation Solution
A solid lithium secondary battery design where the 10-point average roughness (Rz) of the anode current collector and the solid electrolyte layer is maintained within a specific range of 1.8 μm to 2.5 μm, ensuring uniform contact and adhesiveness by forming the surface shape of the solid electrolyte layer to match the anode current collector, thereby preventing short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the surface roughness of the anode current collector is increased to improve contact area with the solid electrolyte layer, then the contact area is improved, but current concentration occurs leading to dendrite formation and short-circuit
Solution Approach 1:
The invention optimizes the surface roughness parameter (Rz) of the anode current collector to a specific range of 1.8 μm to 2.5 μm. This parameter change balances the contact area with the solid electrolyte layer while preventing current concentration that leads to dendrite formation. The controlled roughness ensures sufficient adhesion without creating protrusions that would concentrate current.
2Reliability
If the surface roughness of the anode current collector is decreased to suppress current concentration, then short-circuit risk is reduced, but contact area and adhesiveness with the solid electrolyte layer deteriorate
Solution Approach 1:
The invention establishes a minimum surface roughness threshold of Rz ≥ 1.8 μm to ensure sufficient contact area and adhesiveness between the anode current collector and solid electrolyte layer. This prevents the deterioration of contact while avoiding the current concentration issues associated with excessive roughness.
3Quantity of substance
If Li metal is allowed to precipitate on the anode current collector surface during charging to form the anode active material, then battery capacity is improved, but dendrite formation and short-circuit occur
Solution Approach 1:
The invention performs preliminary action by pre-forming the anode current collector surface with controlled roughness (Rz = 1.8 μm to 2.5 μm) before Li metal precipitation occurs during charging. This preliminary surface preparation ensures that when Li metal precipitates to form the anode active material, it does so on a surface that promotes uniform distribution and prevents dendrite formation, thereby maintaining both high capacity and safety.
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
This design effectively suppresses short-circuit occurrence during charging by achieving balanced contact area, adhesiveness, and reducing current concentration, enhancing the battery's reliability and performance.
Implementation Method 1
a surface shape of the solid electrolyte layer, which faces the anode current collector, is formed in correspondence with a surface shape of the anode current collector
Implementation Method 2
an Li metal is allowed to precipitate as an anode active material through the subsequent charging
Data Source
AI summary
An object of the present invention is to provide a solid lithium secondary battery in which occurrence of short-circuit is suppressed during charging. The object is attained by providing a solid lithium secondary battery comprising an anode current collector, a solid electrolyte layer, a cathode active material layer, and a cathode current collector in this order, wherein the solid electrolyte layer is provided on a surface of the anode current collector, the solid electrolyte layer contains a sulfide solid electrolyte particle, a surface shape of the solid electrolyte layer, which faces the anode current collector, is formed in correspondence with a surface shape of the anode current collector, and 10-point average roughness (Rz) of the surface of the anode current collector on a solid electrolyte layer side, and 10-point average roughness (Rz) of a surface of the solid electrolyte layer on an anode current collector side are in a range of 1.8 μm to 2.5 μm, respectively.