Electrolyte Additives for Lithium-Rich Cathodes With Lower Voltage Decay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-rich, layered electroactive materials used in batteries are susceptible to voltage decay due to structural transformations, which affects their capacity and stability over cycles.
Innovation Solution
Incorporating specific electrolyte additives such as lithium salts, phosphite-based, phosphate-based, and borate-based additives into the electrodes, including materials like xLi2MnO3·(1-x)LiMO2, where M is a transition metal, to enhance cycling stability and mitigate voltage decay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium-rich, layered electroactive materials are used to increase capacity, then energy density is improved, but voltage decay occurs due to structural transformations
Solution Approach 1:
The patent introduces fluorinated cyclic carbonate compounds as intermediary substances in the electrolyte that mediate between the lithium-rich cathode material and the electrolyte. These compounds form protective interfacial layers that prevent direct harmful interactions while allowing lithium ion transport, thereby maintaining high capacity while suppressing voltage decay caused by structural transformations.
Solution Approach 2:
The patent modifies the electrolyte composition by incorporating fluorinated cyclic carbonate compounds with specific molecular structures and fluorine content ratios. By changing the chemical parameters of the electrolyte (adding compounds with 0.1-5 wt% fluorine content), the patent alters the interfacial chemistry to stabilize the cathode structure during cycling, thus preventing voltage decay while preserving high energy density.
2Use of energy by moving object
If lithium-rich, layered electroactive materials are used to increase capacity, then energy density is improved, but capacity retention deteriorates over cycles
Solution Approach 1:
The fluorinated cyclic carbonate compounds act as intermediary agents that form stable protective films on the cathode surface. These films serve as intermediaries that facilitate sustained lithium ion transport while protecting the cathode structure from degradation, thereby improving capacity retention over extended cycling while maintaining the high energy density characteristics of lithium-rich materials.
Solution Approach 2:
The patent applies fluorinated cyclic carbonate compounds that beforehand cushion or protect the cathode material from structural transformations. The compounds pre-form protective interfacial layers before significant degradation can occur, cushioning the cathode against mechanical stress and chemical degradation during subsequent cycling, thus extending the duration of effective capacity.
3Device complexity
If conventional electrolytes are used to maintain simplicity, then device complexity is reduced, but transition metal dissolution increases
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating fluorinated cyclic carbonate compounds with specific molecular weight ranges and fluorine content. This parameter change in the electrolyte chemistry creates more stable interfacial conditions that suppress transition metal dissolution, achieving protection against nickel-manganese dissolution while maintaining relatively simple device architecture.
Solution Approach 2:
The patent creates a composite electrolyte system by combining conventional carbonate solvents with fluorinated cyclic carbonate additives. This composite electrolyte composition leverages the benefits of both components: the conventional solvents provide good ionic conductivity and the fluorinated additives provide protective film formation and dissolution suppression, achieving reduced nickel-manganese dissolution without excessive device complexity.
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 these electrolyte additives improves capacity retention and voltage stability, reducing nickel-manganese dissolution and maintaining performance over a larger number of cycles compared to batteries without additives.
Implementation Method 1
Incorporating specific electrolyte additives such as lithium salts, phosphite-based, phosphate-based, and borate-based additives into the electrodes... to enhance cycling stability and mitigate voltage decay
Implementation Method 2
The electrolyte is suitable for conducting lithium ions between the electrodes
Data Source
AI summary
An electrode for an electrochemical cell that cycles lithium ions is provided. The electrode includes an electroactive material represented by:xLi2MnO3·(1-x)LiMO2 where M is a transition metal selected from the group consisting of: nickel (Ni), manganese, cobalt, aluminum, iron, and combinations thereof and 0.01≤x≤0.99. The electrode also includes an electrolyte additive selected from the group consisting of: a lithium salt additive, a phosphite-based additive, a phosphate-based additive, a borate-based additive, succinonitrile, magnesium bis(trifluoromethanesulfonyl)imide, calcium bis(trifluoromethanesulfonyl)imide, and combinations thereof. For example, the electrolyte additive may be selected from the group consisting of: lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalato)borate, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide, tris(trimethylsilyl)phosphite, tris(2,2,2-trifluoroethyl)phosphite, tris(trimethylsilyl)phosphate, triethyl phosphate, trimethyl borate, tris(trimethylsilyl)borate, tris(pentafluorophenyl)borane, succinonitrile, magnesium bis(trifluoromethanesulfonyl)imide, calcium bis(trifluoromethanesulfonyl)imide, and combinations thereof.