Lithium Secondary Battery Hot Pressing to Prevent Electrode Stack Bending
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Solution Overview
Problem
Lithium secondary batteries with a stacked or lamination-stack type electrode assembly often experience bending during the activation process due to uneven expansion and gas generation, which existing technologies, such as pressurizing during charging, are unable to effectively prevent.
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, where the hot press step laminates the stack surface, using pressures of 294.20 kPa to 980.67 kPa and temperatures of 60°C to 90°C for 3 to 15 minutes, to stabilize the electrode stack before charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a stacked or lamination-stack type electrode assembly is used, then the battery structure is compact and energy density is improved, but bending occurs during the activation process due to uneven expansion and gas generation
Solution Approach 1:
The patent applies a hot press treatment before the activation process to pre-compress the electrode stack and eliminate internal voids. This preliminary action prevents uneven expansion and gas accumulation during subsequent activation, thereby preventing bending while maintaining the compact stacked structure's energy density advantage
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 modifies the electrode stack's internal structure, improving uniformity and preventing the bending phenomenon that would otherwise occur during activation
2Object-generated harmful factors
If pressurizing during charging is applied, then gas discharge is enabled, but bending prevention is insufficient for lamination-stack type electrode assemblies
Solution Approach 1:
Instead of relying solely on pressurizing during charging, the patent performs a hot press treatment before activation to pre-compress the electrode stack. This preliminary compression prevents the formation of internal voids that would lead to bending, making subsequent gas discharge during charging sufficient without causing structural deformation
3Manufacturing precision
If a hot press step is added before charging, then stack surface uniformity is improved and bending is prevented, but manufacturing process complexity increases
Solution Approach 1:
The patent uses hot press treatment to change physical parameters (temperature and pressure) of the electrode stack before activation. This parameter change achieves uniform stack surface and prevents bending, addressing the manufacturing precision requirement while the process is integrated into existing manufacturing workflows
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 method improves the uniformity of the stack surface, preventing bending and ensuring a thickness deviation of 3µm or less and adhesive force deviation of 0.001961 N*mm or less, resulting in a stable and functional lithium secondary battery.
Implementation Method 1
a hot press step of applying pressure and heat to the battery
Implementation Method 2
a hot press step of applying pressure and heat to the battery
Data Source
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AI summary
The present disclosure relates to 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. A method of manufacturing a lithium secondary battery according to an embodiment of the present disclosure 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 battery, and (d) a step of charging the battery, in which a stack surface of the electrode stack is laminated through the hot press. In the process of activating the secondary battery in which the electrolyte is injected, before the initial charging, by performing a hot press process of applying a constant pressure and heat to the secondary battery, it is possible to give an effect of laminating the stack surface of the electrode stack before the charging process, and therefore there is an effect of improving the nonuniformity of the stack surface of the electrode stack due to the expansion of the electrode and the generation of gas during charging.