Polymer Electrolyte Composition for High-Voltage Li-Ion Batteries
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Solution Overview
Problem
Lithium-ion polymer electrolytes have limited voltage resistance on the oxidation side, making them unsuitable for combination with higher potential electrodes.
Innovation Solution
A polymer composition incorporating specific structural units, such as structural units (A), (B1), and (B2), with defined ratios and functional groups, is developed to enhance voltage resistance, along with a method for producing this polymer and an electrolyte composition that includes the polymer, which can be used in batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polymers containing lithium ions are used as electrolytes, then flexibility and ease of contact within solid electrolyte are improved, but voltage resistance on the oxidation side deteriorates
Solution Approach 1:
The patent modifies the chemical structure of the polymer by introducing specific structural units (A), (B1), and (B2) with defined ratios. Structural unit (A) contains lithium ions for ion conduction, while structural units (B1) and (B2) provide high oxidation resistance. By adjusting the molar ratios (0.2 ≤ m ≤ 0.8 for unit A, 0.2 ≤ n ≤ 0.8 for unit B1 or B2), the patent optimizes both flexibility and voltage resistance, achieving oxidation potential of 4.5 V or higher while maintaining ease of contact.
Solution Approach 2:
The patent creates a composite polymer structure combining multiple functional units: structural unit (A) provides lithium ion conduction and flexibility, while structural units (B1) and (B2) contribute high oxidation resistance. This composite approach allows the polymer to simultaneously exhibit good flexibility for contact and superior voltage resistance, resolving the contradiction between ease of operation and reliability.
2Reliability
If oxidation potential is increased to combine with higher potential electrodes, then voltage resistance is improved, but polymer stability may deteriorate
Solution Approach 1:
The patent achieves high oxidation potential (4.5 V or higher) by incorporating structural units (B1) and (B2) with specific chemical compositions. These units are designed to be electrochemically stable at high potentials. By carefully controlling the molar ratios of units (A), (B1), and (B2) within defined ranges, the patent maintains polymer stability while achieving the required oxidation resistance for high-potential electrode compatibility.
Data Source
AI summary
Provided is a polymer including: a structural unit (A) represented by the following formula (A); and a second structural unit represented by the following formula (B1) or (B2), in which a ratio m of the structural unit (A) to total structural units in the polymer is 0.2 to 0.8, and a ratio n of the second structural unit thereto is 0.2 to 0.8.(In formula (A), X is a divalent group, Y is a monovalent group, and M is an alkali metal element.)(In formula (B1), R1 to R4 are each a hydrogen atom or a monovalent group.)(In formula (B2), R15 is a divalent group, and R16 and R17 are each a hydrogen atom or a monovalent group.)