Electrode Stack Hot Pressing for Bend-Free Lithium Secondary Batteries
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Solution Overview
Problem
Lithium secondary batteries with a stacked or lamination-stack type structure experience bending during the activation process due to uneven adhesion and gas expansion, which existing technologies have not adequately addressed.
Innovation Solution
A method involving embedding an electrode stack with an electrolyte in a battery case, followed by aging at room temperature, a hot press step applying pressure and heat, and subsequent charging, which laminates the stack surface to prevent bending by improving surface uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stacked or lamination-stack type electrode assembly is used, then the battery can achieve high energy density and excellent storage characteristics, but the electrode stack bends during the activation process due to uneven adhesion and gas expansion
Solution Approach 1:
The patent applies a hot press treatment before the activation process to pre-compress the electrode stack and ensure uniform contact between stacked electrodes. This preliminary action prevents uneven adhesion and gas expansion during subsequent activation, thereby preventing bending while maintaining high energy density and storage characteristics
Solution Approach 2:
The patent changes physical parameters by applying heat and pressure in a controlled manner during the hot press step. This parameter change ensures uniform compression of the electrode stack, preventing the bending phenomenon that occurs during activation while preserving the high energy density benefits of stacked structures
2Object-generated harmful factors
If gas is discharged during activation by pressurizing the battery, then gas can be vented to the outside, but the bending phenomenon of the lamination and stack type electrode assembly is not effectively prevented
Solution Approach 1:
The patent performs hot press treatment before activation to pre-compress the electrode stack uniformly. This preliminary compression prevents uneven gas expansion during activation, addressing the root cause of bending rather than merely managing gas discharge consequences
Solution Approach 2:
Instead of allowing gas to expand freely during activation and then managing the bending consequence, the patent inverts the approach by pre-compressing the electrode stack before activation. This prevents the bending phenomenon from occurring in the first place, making gas discharge management unnecessary for preventing deformation
3Productivity
If the battery is activated without hot press treatment, then the activation process can proceed normally, but the stack surface uniformity is poor leading to bending
Solution Approach 1:
The patent introduces hot press treatment as a preliminary step before activation to ensure uniform stack surface. This preliminary action addresses the manufacturing precision issue without significantly impacting activation efficiency, as the hot press step is relatively quick and enables smoother subsequent activation
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 method effectively prevents bending by enhancing the uniformity of the stack surface, resulting in a lithium secondary battery with a thickness deviation of 3 μm or less and adhesive force deviation of 5 gf/25 mm or less, ensuring a stable battery structure.
Implementation Method 1
a hot press step of applying pressure and heat to the lithium second battery
Implementation Method 2
a hot press step of applying pressure and heat to the lithium second battery
Data Source
AI summary
A method for manufacturing a secondary battery capable of preventing the phenomenon of bending of an electrode stack generated in an activation step, and a secondary battery produced thereby are provided. The method of manufacturing a lithium secondary battery includes (a) a step of manufacturing a lithium secondary battery by embedding an electrode stack together with an electrolyte in a battery case, (b) a step of aging the battery at room temperature, (c) a hot press step of applying pressure and heat to the lithium secondary battery, and (d) a step of charging the battery, in which a stack surface of the electrode stack is laminated by the hot press step. In the process of activating the secondary battery in which the electrolyte is injected by performing a hot press step, it is possible laminate the stack surface of the electrode stack before the charging process.