Lithium-Ion Battery Electrolyte Additive for Uniform Li2O-Rich SEI
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Solution Overview
Problem
Existing lithium-ion batteries face challenges with lithium metal anodes due to thermodynamic instability, non-uniform solid electrolyte interface (SEI) layers, and low coulombic efficiency, particularly when using carbonate or ether-based electrolytes, leading to issues like lithium dendrite formation and mechanical weakness.
Innovation Solution
The introduction of electrolyte additives with a minimum electrostatic potential (ESP) of -151 to -100 KJ mol-1, such as bis(2,2,2-trifluoroethoxy)methane (BTFM), promotes the formation of a high Li2O content SEI layer with uniform phase distribution, enhancing mechanical stability and coulombic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbonate electrolyte is used with lithium metal anode, then high energy density is achieved, but SEI layer becomes non-uniform and mechanically weak leading to low coulombic efficiency
Solution Approach 1:
The patent introduces electrolyte additives with specific electrostatic potential parameters (minimum ESP of -151 to -100 KJ mol-1) to modify the SEI layer formation process. This parameter-based approach changes the chemical composition and structure of the SEI layer, transforming it from a non-uniform, organic-rich layer to a uniform, inorganic-rich layer with improved mechanical properties and higher coulombic efficiency while maintaining high energy density
Solution Approach 2:
The patent creates a composite SEI layer structure by introducing specific electrolyte additives that promote the formation of inorganic compounds (Li2O, LiF, Li2CO3) within the SEI layer. This composite structure combines the benefits of organic components (flexibility) with inorganic components (mechanical strength and stability), resulting in a SEI layer that is both uniform and mechanically robust, thereby improving coulombic efficiency
2Reliability
If organic-rich SEI layer is formed from carbonate reduction, then lithium metal anode stability is improved, but volume change increases and surface cracking occurs reducing cycle life
Solution Approach 1:
The patent changes the compositional parameters of the SEI layer by introducing electrolyte additives with specific electrostatic potential characteristics. This shifts the SEI layer composition from organic-dominated to inorganic-dominated, fundamentally altering its volume stability properties and preventing the large volume changes and surface cracking that occur with organic-rich SEI layers
Solution Approach 2:
The electrolyte additives act as intermediaries that mediate between the lithium metal anode and the carbonate electrolyte. These additives (with minimum ESP of -151 to -100 KJ mol-1) facilitate the formation of a protective inorganic-rich SEI layer that prevents direct contact between the lithium metal anode and the electrolyte, thereby maintaining anode stability while ensuring SEI layer volume stability
3Reliability
If conventional electrolyte additives are used to promote inorganic-rich SEI layer, then coulombic efficiency stability is improved, but organic by-products from additive decomposition remain problematic
Solution Approach 1:
The patent selects electrolyte additives based on specific electrostatic potential parameters (minimum ESP of -151 to -100 KJ mol-1) that favor complete conversion to inorganic SEI components. This parameter-based selection criterion ensures that the additives promote inorganic-rich SEI layer formation (improving coulombic efficiency stability) while minimizing or eliminating organic by-product generation through controlled decomposition pathways
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 additives achieve a high coulombic efficiency of 99.72% and excellent capacity maintenance, with 90% capacity retention after 200 cycles in Li|LiNi0.8Co0.1Mn0.1O2 full cells and 80% capacity retention after 596 cycles in Cu|NCM811 anodeless cells, addressing the limitations of conventional lithium metal anode-based batteries.
Implementation Method 1
the electrolyte additive has a minimum electrostatic potential (ESP) of about-151 KJ mol-1 to about-100 KJ mol-1
Data Source
AI summary
The electrolyte additive for a lithium-ion battery has a minimum electrostatic potential (ESP) of −151 KJ mol-1 to −100 kJ mol-1.