Positive Electrode Polymer Composition for High-Temperature Li-Ion Stability
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Solution Overview
Problem
Lithium-ion batteries face high-temperature performance limitations, particularly in wearable devices and other applications, due to side reactions between the positive electrode material layer and electrolyte, leading to reduced cycling and storage performance.
Innovation Solution
Incorporating a fluorine-containing polymer and a cyano-containing polymer into the positive electrode material layer with a specific nitrogen to fluorine mole ratio (0.1≤b/a≤0.5) to enhance bonding and reduce side reactions by weakening the oxidizing ability of transition metal ions, using specific polymers and additives to optimize the electrochemical apparatus performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode material layer is used, then manufacturing simplicity is maintained, but high-temperature performance deteriorates due to side reactions between positive electrode active material and electrolyte
Solution Approach 1:
The patent applies composite materials by combining fluorine-containing polymer and cyano-containing polymer in specific proportions within the positive electrode material layer. This composite structure enables synergistic effects where the fluorine-containing polymer provides thermal stability and the cyano-containing polymer reduces side reactions through interaction with transition metal ions, thereby improving high-temperature performance while managing the complexity through a defined compositional framework
Solution Approach 2:
The patent employs parameter changes by precisely controlling the mole ratio of nitrogen to fluorine (b/a ratio) within 0.1-0.5, and adjusting the weight percentages of fluorine-containing polymer (1-5 wt%) and cyano-containing polymer (0.1-3 wt%). These parameter optimizations balance the competing requirements of thermal stability and reduced side reactions, improving high-temperature performance without excessive complexity
2Reliability
If cyano-containing polymer is added to reduce side reactions, then high-temperature stability is improved, but bonding effect between particles deteriorates when nitrogen content is excessive
Solution Approach 1:
The patent resolves this contradiction through precise parameter control, specifically limiting the nitrogen to fluorine mole ratio (b/a) to 0.1-0.5 and controlling cyano-containing polymer content at 0.1-3 wt%. This optimized parameter range ensures sufficient cyano groups to interact with transition metal ions and improve thermal stability, while preventing excessive nitrogen content that would compromise particle bonding strength
Solution Approach 2:
The composite material system combines fluorine-containing polymer and cyano-containing polymer in balanced proportions. The fluorine-containing polymer compensates for potential bonding weaknesses by providing alternative binding mechanisms, while the cyano-containing polymer delivers thermal stability. This composite approach allows both functions to coexist without mutual interference
3Temperature
If fluorine-containing polymer is added to improve thermal stability, then high-temperature resistance is enhanced, but manufacturing complexity increases due to precise ratio control requirements
Solution Approach 1:
The patent manages manufacturing complexity through defined parameter ranges rather than precise fixed values. The fluorine-containing polymer content is specified as 1-5 wt% and cyano-containing polymer as 0.1-3 wt%, with the b/a ratio controlled within 0.1-0.5. These ranges provide manufacturing flexibility while ensuring thermal stability performance, balancing ease of manufacture with performance requirements
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
Improves high-temperature cycling and storage performance by minimizing side reactions and maintaining structural integrity, thereby enhancing the electrochemical apparatus's overall performance.
Implementation Method 1
after cyano functional groups having strong electronegativity interact with transition metal ions of the positive electrode active material in the positive electrode material layer at full charge, oxidizing ability of the transition metal ions is weakened
Implementation Method 2
adding the fluorine-containing polymer and the cyano-containing polymer into the positive electrode material layer and controlling the ratio b/a of the mole number b of nitrogen to the mole number a of fluorine in the positive electrode material layer so that b/a satisfies the above relationship enable a good bonding effect between particles in the positive electrode material layer
Data Source
AI summary
An electrochemical apparatus includes a positive electrode plate. The positive electrode plate includes a positive electrode material layer. The positive electrode material layer includes a fluorine-containing polymer and a cyano-containing polymer. A ratio b/a of a mole number b of nitrogen to a mole number a of fluorine in the positive electrode material layer satisfies 0.1≤b/a≤0.5. Adding the fluorine-containing polymer and the cyano-containing polymer in the positive electrode material layer and controlling the ratio b/a satisfies the above relationship enable a good bonding effect between particles in the positive electrode material layer. In addition, after cyano functional groups interact with transition metal ions of the positive electrode active material at full charge, oxidizing ability of transition metal ions is weakened, reducing side reactions between the positive electrode material layer and electrolyte, thereby improving high-temperature performance of the electrochemical apparatus.