Alginic Acid Salt Coated Olivine Cathode for High-Rate Battery Stability
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Solution Overview
Problem
Nonaqueous electrolyte rechargeable batteries experience performance deterioration when charging and discharging at high rates due to local expansion and contraction of positive electrode active materials, leading to electrolyte ejection and lithium ion concentration unevenness, which affects their high-rate characteristic.
Innovation Solution
Incorporating a positive electrode with a carbon surface layer and using lithium complex oxides with layered and olivine crystal structures, along with alginic acid salt to enhance adhesion between active materials and the collector, preventing local expansion and contraction and maintaining high performance even at high rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium complex oxide with olivine structure is used as positive electrode active material, then output at low SOC is enhanced, but performance deteriorates when charging and discharging are performed repeatedly at high rate
Solution Approach 1:
The patent uses a composite structure consisting of lithium complex oxide particles with olivine crystal structure coated with carbon material and alginic acid salt. This composite material combines the high output characteristics of olivine structure with the adhesion benefits of carbon and alginic acid salt coatings, resolving the contradiction between power output and performance stability.
Solution Approach 2:
The patent applies different materials to different parts of the active material particles: the core is lithium complex oxide with olivine structure for high output, while the surface is coated with carbon material and alginic acid salt for enhanced adhesion and stability. This local differentiation allows each region to perform its specific function optimally.
2Productivity
If charging and discharging are performed repeatedly at high rate, then capacity utilization is improved, but local expansion and contraction of positive electrode active material occurs
Solution Approach 1:
The patent applies carbon material and alginic acid salt coatings to the surface of lithium complex oxide particles before they are assembled into the electrode. This pre-protection layer cushions the particles against expansion and contraction forces during high-rate charging and discharging, preventing structural degradation and maintaining compositional stability.
3Ease of manufacture
If conventional positive electrode structure is used, then manufacturing is simple, but adhesion between active material and collector is insufficient
Solution Approach 1:
The patent introduces alginic acid salt as an intermediary substance between the lithium complex oxide active material particles and the positive electrode collector. This intermediary enhances adhesion strength by forming strong bonds with both the active material and the collector, while maintaining manufacturing simplicity through a straightforward coating process.
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 configuration enhances the battery's output at low State Of Charge and maintains high performance by preventing electrolyte ejection and resistance unevenness, thus preventing deterioration in high-rate characteristics.
Implementation Method 1
a carbon film provided at least at a part of a surface of the particle made of second lithium complex oxide
Implementation Method 2
the alginic acid salt can enhance an adhesion between second positive electrode active materials, an adhesion between the second positive electrode active material and the conducting agent, and an adhesion between the second positive electrode active material and the positive electrode collector
Implementation Method 3
The first positive electrode active material is made of first lithium complex oxide having a layered crystal structure. The second positive electrode active material includes a particle made of second lithium complex oxide having an olivine crystal structure
Data Source
AI summary
A positive electrode collector includes a main body layer and a surface layer. The surface layer is provided at least at a portion of a surface of the main body layer where the positive electrode mixture layer is provided, and is made of a carbon material. A first positive electrode active material is made of first lithium complex oxide having a layered crystal structure. A second positive electrode active material includes a particle made of second lithium complex oxide having an olivine crystal structure, a carbon film provided at least at a part of a surface of the particle, and alginic acid salt provided at least at a part of a surface of the carbon film. A conducting agent in the positive electrode mixture layer includes a carbon particle and alginic acid salt provided at least at a part of a surface of the carbon particle.