Vinylsilane Additives for High Voltage Battery Electrolytes
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Solution Overview
Problem
Conventional electrolytes in lithium-ion batteries are unstable at high voltages and temperatures, leading to decomposition and degradation of battery performance, particularly in high-energy cathode materials, resulting in limited cycle life and safety concerns.
Innovation Solution
A liquid electrolyte formulation comprising a lithium salt, solvent, and additives represented by the formula (M-Rx)y, where M is a metalloid moiety and Rx includes vinyl or fluorine moieties, which forms a stable solid electrolyte interphase (SEI) to prevent oxidative decomposition at the cathode and maintain electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in lithium-ion batteries, then the batteries can operate at standard voltages, but the electrolytes decompose at high voltages above 4.3V leading to poor cycle life and safety issues
Solution Approach 1:
The patent applies preliminary action by introducing additives that pre-form protective films on electrode surfaces before the electrolyte decomposition occurs. These additives (such as vinylene carbonate and fluoroethylene carbonate) react first during initial charging cycles to create stable solid electrolyte interphase (SEI) layers on the anode and protective films on the cathode, preventing subsequent electrolyte decomposition at high voltages above 4.3V.
Solution Approach 2:
The patent uses intermediary substances (additives) that mediate between the electrolyte and electrode surfaces. These intermediary compounds form interfacial layers that prevent direct contact and harmful reactions between the conventional electrolyte and high-voltage cathode materials, enabling stable operation at voltages above 4.3V without compromising electrolyte stability.
2Quantity of substance
If the operating voltage is increased above 4.3V to access higher capacity, then the battery capacity increases, but the electrolyte decomposes leading to gas generation and performance deterioration
Solution Approach 1:
The additives perform preliminary protective action by forming stable films on electrode surfaces before electrolyte decomposition can occur. This preliminary film formation prevents the generation of harmful gases (CO2, O2, ethylene, H2) that would otherwise be produced through electrolyte decomposition at high voltages, enabling safe operation above 4.3V.
Solution Approach 2:
The patent converts the potentially harmful decomposition reactions into beneficial protective film formation. The additives are designed to decompose preferentially and form stable, protective layers that prevent further decomposition of the bulk electrolyte, thereby converting what would be harmful gas-generating reactions into beneficial surface passivation that enables high-voltage operation.
3Reliability
If organic compounds with polymerizable functional groups are used to form SEI, then passivation films are created, but the SEI becomes non-uniform with heterogeneous composition leading to poor mechanical stability
Solution Approach 1:
The patent applies homogeneity by combining multiple additives (vinylene carbonate and fluoroethylene carbonate) that work synergistically to form uniform SEI layers. This combination ensures consistent film composition and properties across the electrode surface, preventing the heterogeneous, non-uniform SEI structures that lead to mechanical instability and poor cycle life.
Solution Approach 2:
The patent uses composite material principles by creating SEI layers with complex compositions containing multiple components (organic and inorganic lithium salts, oligomers, and polymers) in controlled ratios. This composite structure, formed through the synergistic action of multiple additives, provides both mechanical stability and electrochemical stability that single-component SEI layers cannot achieve.
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 electrolyte solution enhances capacity retention and stability of lithium-ion batteries, allowing operation at higher voltages and temperatures, significantly improving cycle life and safety by forming a protective film that inhibits undesirable reactions.
Implementation Method 1
These additives likely undergo polymerization during cell charging to form passivation films on the electrodes
Implementation Method 2
A liquid electrolyte serves to transport ions between electrodes in a battery
Implementation Method 3
additives have been incorporated into the electrolyte to decompose on the electrode to form a protective film called a solid electrolyte interphase (SEI)
Implementation Method 4
these additives likely undergo polymerization during cell charging to form passivation films on the electrodes
Data Source
AI summary
Described herein are additives for use in electrolytes that provide a number of desirable characteristics when implemented within batteries, such as high capacity retention during battery cycling at high temperatures. In some embodiments, a high voltage electrolyte includes a base electrolyte and one or more vinylsilane or fluorosilane additives, which impart these desirable performance characteristics.