Lithium Metal Anode Electrolyte for Thermal Stability
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Solution Overview
Problem
Lithium-metal-containing batteries face safety issues due to decomposition reactions at elevated temperatures, leading to spontaneous heating and explosive gas formation, limiting their use beyond micro-design scales despite their potential for higher energy density compared to lithium-ion batteries.
Innovation Solution
A galvanic cell with a lithium metal or alloy anode and an electrolyte containing lithium bis(oxalato)borate and specific lithium complex salts in an aprotic solvent, which forms a thermally stable layer on the lithium surface, reducing decomposition reactions and gas formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal or lithium alloy anode is used, then energy density is improved, but safety deteriorates due to decomposition reactions at elevated temperatures
Solution Approach 1:
The patent introduces lithium bis(oxalato)borate (LiBOB) as an intermediary substance that mediates between the lithium metal anode and the electrolyte. LiBOB forms a protective interface layer on the lithium surface that prevents direct contact and decomposition reactions, thereby maintaining safety while allowing the high-energy-density lithium metal anode to function
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating specific additives (lithium complex salts with formulas I and II) alongside LiBOB. This parameter change transforms the electrolyte's interaction with lithium metal, creating a stable solid electrolyte interface (SEI) layer that prevents thermal runaway while maintaining ionic conductivity
2Quantity of substance
If lithium metal anode is used, then specific lithium charge is improved, but thermal stability deteriorates leading to spontaneous heating
Solution Approach 1:
The patent applies preliminary action by having LiBOB and the lithium complex salts form a stable protective layer on the lithium metal surface before thermal runaway can occur. This pre-formed interface layer acts as a thermal barrier that prevents the exothermic decomposition reactions that would otherwise lead to spontaneous heating
Solution Approach 2:
The patent converts the potentially harmful decomposition reactions into a beneficial stable interface formation. The lithium complex salts and LiBOB undergo controlled reactions with lithium metal to form a stable solid electrolyte interface that prevents uncontrolled thermal runaway, transforming a safety hazard into a protective mechanism
3Quantity of substance
If common electrolyte solutions are used with lithium metal, then energy density is improved, but harmful factors increase due to gas formation and explosive reactions
Solution Approach 1:
The patent uses LiBOB and lithium complex salts as intermediary substances that form a protective interface layer between the lithium metal anode and the organic electrolyte. This intermediary layer prevents direct decomposition reactions that would generate harmful gases, while still allowing lithium ion transport for high energy density
4Reliability
If graphite intercalation anode is used, then safety is improved, but energy density deteriorates due to lithium intercalation limitations
Solution Approach 1:
The patent introduces LiBOB and lithium complex salts as intermediary substances that enable the use of lithium metal anodes by forming protective interface layers. This allows the system to achieve the high energy density of lithium metal while maintaining the safety characteristics needed for practical applications
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 solution effectively prevents thermal runaway and gas formation, enabling the production of safe, high-energy-density batteries suitable for large-format applications.
Implementation Method 1
it has been found that when mixed with one of the cited complex additives, LiBOB appears to form a thin, extremely thermally stable layer on the lithium metal or lithium metal alloy surface, which effectively prevents a decomposition reaction between the lithium-metal-containing anode material and the electrolyte component
Implementation Method 2
In unfavourable operating conditions (e.g. elevated temperatures), decomposition reactions can occur which lead to a dangerous run-away situation
Data Source
AI summary
A galvanic cell having a lithium metal or an alloy comprising a lithium metal as anode material, having an electrolyte comprising lithium bis(oxalate)borate and at least one other lithium complex salt in an aprotic solvent or solvent mixture, in the ratio of lithium complex salt in the conducting salt equals 0.01 to 20 mol %.