Lithium-Ion Battery Electrolyte Refilling for Pressure Stability
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Solution Overview
Problem
The addition of LiPF2(C2O4)2 as an additive agent in lithium-ion secondary batteries leads to gas generation during decomposition, causing increased internal pressure, which can result in excessive surface film formation and further pressure increases, making it challenging to maintain battery internal pressure stability.
Innovation Solution
A method involving the initial charging and discharging of a lithium-ion secondary battery with a first electrolyte solution containing a film forming agent, followed by the discharge of this solution and refilling with a second electrolyte solution at a concentration of less than 0.005 mol/L, minimizing the amount of film forming agent and subsequent gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF2(C2O4)2 is added as an additive agent to form a surface film, then the surface film formation is improved, but the internal pressure increases due to gas generation
Solution Approach 1:
The patent applies preliminary action by performing initial charging and discharging cycles before the battery is sealed. During these preliminary cycles, the film forming agent decomposes and forms the desired surface film on the electrodes. This preliminary action ensures that the surface film is formed before the battery is hermetically sealed, preventing subsequent gas generation and internal pressure increase.
Solution Approach 2:
The patent applies parameter changes by controlling the concentration of the film forming agent in the electrolyte solution. By adjusting the concentration to an optimal level, the patent achieves sufficient surface film formation while minimizing excessive decomposition and gas generation, thus balancing the contradiction between film quality and internal pressure.
2Reliability
If excess LiPF2(C2O4)2 remains in the electrolyte solution, then the surface film may be excessively formed, but gases are further generated causing internal pressure to increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of the film forming agent in the electrolyte solution. By optimizing this parameter, the patent achieves sufficient surface film formation while minimizing excessive decomposition and gas generation, thus balancing the contradiction between film quality and internal pressure.
Solution Approach 2:
The patent applies feedback by monitoring the surface film formation process during initial charging and discharging cycles. Based on this feedback, the patent can determine when sufficient film formation has been achieved and adjust or stop the decomposition process to prevent excessive gas generation from excess additive agent decomposition.
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 approach ensures the formation of an appropriate surface film while significantly reducing the internal pressure increase, enhancing battery stability and longevity by minimizing gas production from residual film forming agents.
Implementation Method 1
the LiPF2(C2O4)2 is decomposed during initial charging to form a stable surface film on the surfaces of the positive electrode and/or the negative electrode
Implementation Method 2
allowing smooth insertion and deinsertion of lithium ions
Data Source
AI summary
A method of manufacturing a lithium-ion secondary battery proposed herein includes the following steps of: preparing a battery in which an electrode assembly is enclosed in a battery case; filling a first electrolyte solution containing a film forming agent into the battery case; charging and discharging the battery filled with the first electrolyte solution; discharging the first electrolyte solution from the battery that has been charged and discharged; and filling a second electrolyte solution containing a film forming agent at a concentration of less than 0.005 mol/L into the battery case from which the first electrolyte solution has been discharged.