Lithium-Ion Anode SEI Formation for Propylene Carbonate Electrolytes
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Solution Overview
Problem
Lithium-ion batteries face incompatibility issues with propylene carbonate, leading to undesirable side reactions that inhibit lithium ion intercalation when used with graphite anodes, limiting its application in lithium-ion battery electrolytes.
Innovation Solution
A two-step method is introduced to form a solid electrolyte interface in lithium-ion battery electrodes, first using ethylene carbonate to create a solid electrolyte interface and then introducing propylene carbonate, allowing for robust growth and compatibility with propylene carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If propylene carbonate is used in the electrolyte for lithium-ion batteries, then low-temperature performance is improved, but undesirable side reactions occur that inhibit lithium ion intercalation
Solution Approach 1:
The patent applies preliminary action by pre-forming a solid electrolyte interface (SEI) layer using ethylene carbonate before introducing propylene carbonate. This pre-formed SEI layer acts as a protective barrier that prevents the harmful side reactions between propylene carbonate and graphite anodes, while still allowing lithium ion intercalation. The preliminary formation step creates a stable interface that enables subsequent use of propylene carbonate for improved low-temperature performance.
Solution Approach 2:
The patent uses ethylene carbonate as an intermediary substance that mediates between propylene carbonate and the graphite anode. The ethylene carbonate forms a stable SEI layer that acts as an intermediary barrier, preventing direct contact and harmful reactions between propylene carbonate and graphite, while still permitting lithium ion transport. This intermediary layer resolves the contradiction by decoupling the beneficial low-temperature effects of propylene carbonate from its harmful side reactions.
2Temperature
If propylene carbonate is used in the electrolyte, then low-temperature performance is enhanced, but side reactions inhibit battery operation
Solution Approach 1:
The patent converts the harmful side reactions of propylene carbonate into a beneficial outcome by using ethylene carbonate to form a protective SEI layer. The harmful propylene carbonate molecules are redirected to react with ethylene carbonate instead of graphite, forming a stable interface layer. This converts the originally harmful chemical reactivity into a beneficial protective function that enhances low-temperature performance without the detrimental side effects.
Solution Approach 2:
Ethylene carbonate serves as an intermediary that absorbs the harmful chemical interactions. Instead of allowing propylene carbonate to directly react with graphite anodes, the ethylene carbonate intercepts these interactions and forms a stable SEI layer, thereby eliminating the harmful side reactions while preserving the low-temperature performance benefits.
3Reliability
If ethylene carbonate is used in the electrolyte, then compatibility with graphite anodes is ensured, but low-temperature performance is limited
Solution Approach 1:
The patent merges the advantages of both ethylene carbonate and propylene carbonate by combining them in a two-step electrolyte formation process. Ethylene carbonate is first used to form a compatible SEI layer with graphite anodes, ensuring reliability and compatibility. Then propylene carbonate is introduced to provide enhanced low-temperature performance. The combination merges the compatibility benefits of ethylene carbonate with the temperature performance benefits of propylene carbonate.
Solution Approach 2:
The patent applies preliminary action by first using ethylene carbonate to create a compatible interface with graphite anodes before introducing propylene carbonate. This preliminary step ensures proper compatibility and sets the stage for subsequent addition of propylene carbonate, which would otherwise be incompatible but becomes beneficial when added after SEI formation.
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 method enables the use of propylene carbonate in lithium-ion battery electrolytes, enhancing low-temperature performance and stability by forming a robust solid electrolyte interface that protects graphite anodes from propylene carbonate's incompatible chemistry.
Implementation Method 1
The lithium-ion battery cell is cycled for at least one charging cycle such that one or more solid electrolyte interfaces are formed
Data Source
AI summary
A method for forming a solid electrolyte interface on a lithium-ion battery electrode is provided. The method includes a step of introducing a first quantity of a first electrolyte composition into a container. The container includes at least one lithium-ion battery cell and the first electrolyte composition including ethylene carbonate. The lithium-ion battery cell is cycled for at least one charging cycle such that one or more solid electrolyte interfaces are formed. A second electrolyte composition is introduced into the container to form a final electrolyte composition, the second electrolyte composition including propylene carbonate.