Flexible Coated Solid Electrolyte Particles for Thermal Stability
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Solution Overview
Problem
Current lithium ion batteries using conventional liquid electrolytes based on organic solvents face safety concerns due to their volatile and flammable nature, especially at elevated temperatures, leading to limited operating temperatures and poor cycle life due to resistive film formation on electrode surfaces.
Innovation Solution
The use of a lithium ion cell with an electrolyte comprising up to 20% volume of ionic liquid additives and a composite electrolyte with solid electrolyte particles coated by flexible ionic conductive material, along with a surface layer on the anode to bond ionic liquid additives, preventing lithium metallization and electrolyte decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid electrolytes based on organic solvents are used, then electrochemical performance is achieved, but thermal and chemical stability deteriorates at elevated temperatures
Solution Approach 1:
The patent uses composite electrolytes combining solid electrolyte particles (such as Li1.3Al0.3Phosphorus0.3O2.7 or Li2SiO3) with liquid electrolyte components. This composite structure provides both the electrochemical performance of liquid electrolytes and the thermal/chemical stability of solid electrolytes, enabling safe operation at elevated temperatures up to 60°C and beyond.
Solution Approach 2:
The patent modifies the physical state and composition parameters of the electrolyte by incorporating ionic liquids (which have negligible vapor pressure and high thermal stability) and solid electrolyte particles into the conventional liquid electrolyte system. This parameter change transforms the electrolyte from purely liquid to a hybrid solid-liquid system with improved thermal and chemical properties.
2Productivity
If carbonate solvents are used with Li salts, then electrochemical reactions occur, but resistive film forms on electrode surface reducing cycle life
Solution Approach 1:
The patent introduces ionic liquid additives and solid electrolyte particles as intermediary substances between the electrode and the conventional liquid electrolyte. These intermediaries form stable protective films on the electrode surface that prevent direct harmful reactions between carbonate solvents and Li salts, thereby reducing resistive film formation and extending cycle life.
Solution Approach 2:
The patent extracts or removes the harmful resistive film formation mechanism by using ionic liquids and solid electrolyte particles that do not participate in the detrimental side reactions. Instead, they form stable, conductive protective layers that eliminate the cycle-life-degrading effects of conventional carbonate-based electrolytes.
3Reliability
If ionic liquid additives are added to electrolyte, then thermal stability improves, but viscosity increases
Solution Approach 1:
The patent applies ionic liquid additives locally at the electrode-electrolyte interface rather than uniformly throughout the bulk electrolyte. This localized application provides thermal stability and protective film formation where needed while minimizing the overall viscosity increase and maintaining bulk ionic conductivity for efficient ion transport.
Solution Approach 2:
The patent optimizes the concentration parameter of ionic liquid additives to achieve the desired balance between thermal stability and ionic conductivity. By controlling the amount of ionic liquid added and combining it with solid electrolyte particles, the system achieves improved thermal properties without excessive viscosity increase that would harm ionic conductivity.
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 solution enhances the thermal and chemical stability of lithium ion batteries, allowing operation over a wider temperature range without compromising electrochemical performance and extends the cycle life by preventing lithium metallization and electrolyte decomposition.
Implementation Method 1
a composite electrolyte with solid electrolyte particles coated by flexible ionic conductive material
Implementation Method 2
enables efficient lithium ion transport
Implementation Method 3
anode comprises a surface layer configured to bond at least a portion of the at least one ionic liquid additive
Implementation Method 4
bond at least a portion of the at least one ionic liquid additive
Implementation Method 5
ionic liquid additives... having negligible vapor pressure
Implementation Method 6
enhances the thermal and chemical stability of lithium ion batteries
Data Source
AI summary
Electrolytes, anode material particles and methods are provided for improving performance and enhancing the safety of lithium ion batteries. Electrolytes may comprise ionic liquid(s) as additives which protect the anode material particles and possibly bind thereto; and/or may comprise a large portion of fluoroethylene carbonate (FEC) and/or vinylene carbonate (VC) as the cyclic carbonate component, and possibly ethyl acetate (EA) and/or ethyl methyl carbonate (EMC) as the linear component; and/or may comprise composite electrolytes having solid electrolyte particles coated by flexible ionic conductive material. Ionic liquid may be used to pre-lithiate in situ the anode material particles. Disclosed electrolytes improve lithium ion conductivity, prevent electrolyte decomposition and/or prevents lithium metallization on the surface of the anode.