Positive Electrode Additive Coating to Suppress Battery Side Reactions
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Solution Overview
Problem
Lithium secondary batteries face stability issues due to side reactions between lithium transition metal oxides and electrolyte liquids, leading to gas generation and performance degradation, particularly with additives like Li2NiO2 which have low synthesis rates and react with LiOH and Li2CO3, causing gelation and instability.
Innovation Solution
An additive comprising aluminum-doped lithium transition metal oxide, Li3PO4, Li5AlO4, and Li3BO3 is used, where these components form a coating layer or are doped onto the lithium transition metal oxide to suppress side reactions with the electrolyte, improving battery stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li2NiO2 is used as a positive electrode additive to increase irreversible capacity, then battery capacity is improved, but side reactions with electrolyte liquid cause gas generation and stability degradation
Solution Approach 1:
Li3PO4, Li5AlO4, and Li3BO3 are introduced as intermediary substances that form protective coating layers on the Li2NiO2 surface. These intermediary materials prevent direct contact between Li2NiO2 and the electrolyte liquid, thereby eliminating side reactions and gas generation while preserving the irreversible capacity benefit
Solution Approach 2:
The invention creates a composite additive system combining Li2NiO2 with Li3PO4, Li5AlO4, and Li3BO3. This composite material integrates the high irreversible capacity of Li2NiO2 with the stability and protective properties of the other compounds, achieving both capacity improvement and stability enhancement simultaneously
2Ease of manufacture
If Li2O and NiO are used as starting materials for Li2NiO2 synthesis, then the additive can be manufactured, but low synthesis rate leaves unreacted substances that cause gelation and gas generation
Solution Approach 1:
The harmful unreacted Li2O and NiO substances are extracted from the final additive composition by optimizing the synthesis process. The invention specifies precise molar ratios and synthesis conditions to ensure complete reaction, removing the source of gelation and gas generation problems
Solution Approach 2:
The invention changes the synthesis parameters by specifying precise molar ratios (Li2O:NiO = 1.05:1 to 1.15:1) and controlled heating conditions (300-700°C for 10-32 hours). These parameter changes ensure complete reaction of starting materials, eliminating unreacted substances that cause harmful effects
3Power
If LiCoO2 is used as positive electrode active material to achieve high operating voltage and excellent capacity, then battery performance is improved, but poor thermal properties and high cost limit large-scale use
Solution Approach 1:
Aluminum is doped into specific lattice positions of the LiCoO2 crystal structure at controlled concentrations (x = 0.001 to 0.005 in Li2Ni1-xAlxO2). This local modification improves thermal stability at specific sites without significantly compromising the overall high voltage and capacity properties of the material
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 additive significantly reduces gas generation and enhances battery stability by preventing side reactions, maintaining performance over multiple cycles and long-term storage, thereby extending the battery's lifespan.
Implementation Method 1
a lithium transition metal oxide, having an aluminum-doped form
Implementation Method 2
these components form a coating layer or are doped onto the lithium transition metal oxide to suppress side reactions with the electrolyte
Data Source
AI summary
An additive for a positive electrode of a lithium secondary battery, the additive including a lithium transition metal oxide, Li3PO4, Li5AlO4 and Li3BO3. The lithium transition metal oxide has an aluminum-doped form. The additive including Li3PO4, Li5AlO4 and Li3BO3 together with the lithium transition metal oxide has functionality of improving stability of a battery when used in a positive electrode of a lithium secondary battery. The Li3PO4, the Li5AlO4 and the Li3BO3 are evenly mixed with the lithium transition metal oxide or some thereof form a partial coating layer, or a portion of aluminum is doped to the lithium transition metal oxide to suppress the lithium transition metal oxide from causing a side reaction with an electrolyte liquid.