Mn(TFSI)2 Metal Salt Additive for Li-Ion Battery Impedance Stabilization
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Solution Overview
Problem
Conventional lithium-ion battery electrolytes do not adequately stabilize battery cell impedance and resistance, leading to performance degradation due to parasitic reactions at the electrode/electrolyte interface.
Innovation Solution
Incorporating manganese bis(trifluoromethanesulfonyl)imide salt (Mn(TFSI)2) as an additive in the electrolyte, combined with lithium hexafluorophosphate and solvents like ethylene carbonate, to enhance capacity retention and impedance stability in Li-ion battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes with lithium salts, solvents and additives (propane sultone, vinylene carbonate) are used, then the SEI layer quality is improved, but the impedance stability and resistance are not sufficiently stabilized
Solution Approach 1:
The patent introduces a metal salt (Mn(TFSI)2) at a specific concentration range (0.001M to 0.01M) to modify the electrolyte composition parameters. This parameter change stabilizes the impedance by controlling the formation and properties of the SEI layer, resolving the contradiction between SEI quality and impedance stability.
Solution Approach 2:
The patent creates a composite electrolyte system combining lithium salts (LiPF6), solvents (carbonate mixtures), conventional additives (propane sultone, vinylene carbonate), and the novel metal salt Mn(TFSI)2. This composite approach synergistically improves both SEI layer quality and impedance stability, addressing the limitations of conventional single-component additives.
2Productivity
If conventional electrolytes are used, then basic battery operation is maintained, but capacity retention deteriorates due to parasitic reactions at the electrode/electrolyte interface
Solution Approach 1:
The metal salt Mn(TFSI)2 acts as an intermediary substance in the electrolyte that mediates the interaction between the electrode and conventional electrolyte components. It modifies the interface chemistry to reduce parasitic reactions while maintaining basic battery operation, thereby improving capacity retention over time.
Solution Approach 2:
The metal salt promotes the preliminary formation of a stable and protective SEI layer during initial cycles. This preliminary action prevents subsequent parasitic reactions at the electrode/electrolyte interface, ensuring long-term capacity retention while maintaining normal battery operation.
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 use of Mn(TFSI)2 improves capacity retention by 2% after 100 cycles and reduces cumulative irreversible capacity, while stabilizing impedance, thereby extending the battery's functional life and preventing premature degradation.
Implementation Method 1
The cell according to the invention comprises an electrolyte comprising at least one additive, at least one lithium salt, at least one solvent and at least one metal salt of formula (I)... stabilizing the impedance of the battery cell
Implementation Method 2
improving the electrochemical performance of said cell, particularly in terms of capacity retention but also in terms of the impedance of the cell... reduces cumulative irreversible capacity
Data Source
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Figure 3
AI summary
The invention relates to a Li-ion battery cell comprising a material for a positive electrode, a carbon-based material for a negative electrode, a separator and an electrolyte, said electrolyte comprising: - at least one additive; - at least one lithium salt; - at least one solvent; and - at least one electrically neutral metal salt of formula (I): wherein: - A is a metal chosen from Mn, Fe, Ni, Co, Cu, Cr, Ag and Zn; - B is chosen from Cl, ClO4, TFSI, [N(SO2"R)2] where R = CzF2z+1 or 1 ≤ z < 8, FSI, CF3SO3 and CF3CO2.