In-Situ Polymer Electrolyte for High-Voltage Li-Ion Batteries
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to thermal runaway, and existing polymer electrolytes have limitations such as low electrical conductivity, poor high voltage resistance, and high production costs, which are not adequately addressed by current solid, semi-solid, or liquid state electrolytes.
Innovation Solution
A polymer electrolyte comprising a combination of carbonate, ester, boron, and fluorine structures, with specific molecular weight ranges and functional groups, is developed, allowing for in-situ polymerization within a lithium-ion battery, enhancing electrical conductivity and high voltage resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cross-linked polymer electrolyte is prepared to improve performance, then electrochemical stability is improved, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing the cross-linked polymer electrolyte material before battery assembly. The cross-linking reaction is performed in advance to create a stable three-dimensional network structure, which is then directly used in battery manufacturing. This eliminates the need for complex in-situ cross-linking processes during battery assembly, simplifying the overall processing while maintaining electrochemical stability.
2Strength
If high molecular weight polymer is used to improve mechanical strength, then structural stability is improved, but electrical conductivity deteriorates
Solution Approach 1:
The patent optimizes the molecular weight parameter within a specific range (10,000-500,000 g/mol) to balance mechanical strength and electrical conductivity. It also controls the degree of crystallinity and introduces amorphous regions that facilitate ion transport, thereby achieving both structural stability and adequate electrical conductivity.
Solution Approach 2:
The patent incorporates inorganic fillers and plasticizers into the high molecular weight polymer matrix to create a composite electrolyte. These additives create additional ion transport pathways and reduce crystallinity, maintaining mechanical integrity while improving electrical conductivity.
3Quantity of substance
If conventional electrolyte is used to achieve high energy density, then capacity is improved, but safety deteriorates due to thermal runaway
Solution Approach 1:
The patent converts the harmful flammability of conventional liquid electrolytes into a benefit by using the polymer electrolyte's inherent flame resistance. The solid polymer matrix inherently prevents the thermal runaway that plagues liquid electrolytes, while still enabling high energy density through optimized composition and structure.
Solution Approach 2:
The patent creates a composite electrolyte system that combines the safety advantages of solid polymers with the high ionic conductivity needed for high energy density applications. The composite structure enables the battery to achieve high capacity while eliminating thermal runaway risks.
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 polymer electrolyte improves the electrochemical stability and electrical conductivity of lithium-ion batteries, reducing the risk of thermal runaway and enabling better performance in high energy density applications with simplified processing.
Implementation Method 1
allowing for in-situ polymerization within a lithium-ion battery
Data Source
Figure 1
AI summary
Provided are a polymer electrolyte and a lithium-ion battery including the polymer electrolyte. A preparation method of a polymer electrolyte includes: (1) dissolving a functional polymer with an organic solvent, and uniformly mixing to obtain a system A, where the functional polymer has a mass ratio of 0.2%-30% in the system A; (2) uniformly mixing the A system, a lithium salt, and a functional additive to obtain a mixed solution; (3) subjecting the mixed solution to in-situ polymerizing to obtain the polymer electrolyte. The polymer electrolyte has better affinity with anions of the lithium salt and relatively high electrical conductivity, and greatly improves the performance of the semi-solid state battery. The semi-solid state battery prepared is based on the existing lithium-ion battery processing technology, has good processing performance and electrochemical performance, and has certain application prospects.