Nonaqueous Electrolyte Battery Silicon Negative Electrode
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries using metallic silicon or silicon oxide as negative electrode active materials experience rapid capacity retention deterioration during charge/discharge cycles.
Innovation Solution
A nonaqueous electrolyte secondary battery design incorporating a positive electrode with lithium-cobalt composite oxide and lithium-nickel-cobalt-manganese composite oxide of specific average primary particle sizes, combined with a negative electrode containing silicon or silicon oxide, and a separator, to maintain capacity retention during repeated cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic silicon or silicon oxide is used as negative electrode active material to increase capacity, then theoretical capacity increases significantly, but capacity retention deteriorates rapidly during charge/discharge cycles
Solution Approach 1:
The patent applies parameter changes by precisely controlling the average primary particle size of lithium-nickel-cobalt-manganese composite oxide within 1.0 μm to 5.0 μm, and the mass ratio between lithium-cobalt composite oxide and lithium-nickel-cobalt-manganese composite oxide within 95:5 to 50:50. These parameter optimizations resolve the contradiction by achieving both high capacity and excellent capacity retention of 95% or more after 500 cycles
Solution Approach 2:
The patent uses composite materials by combining lithium-cobalt composite oxide and lithium-nickel-cobalt-manganese composite oxide in specific proportions as the positive electrode active material. This composite approach allows the battery to achieve high capacity while maintaining excellent cycle characteristics, resolving the contradiction between capacity improvement and capacity retention
2Quantity of substance
If lithium-nickel-cobalt-manganese composite oxide is added to increase capacity, then battery capacity increases, but manufacturing complexity increases due to particle size control requirements
Solution Approach 1:
The patent defines specific parameter ranges for average primary particle size (1.0 μm to 5.0 μm) and mass ratios (95:5 to 50:50) that balance capacity enhancement with manufacturing feasibility. These parameter specifications provide clear manufacturing targets while achieving the desired performance improvement
3Reliability
If cobalt content is increased to improve battery characteristics, then cycle characteristics improve, but cost increases due to expensive and scarce cobalt resource
Solution Approach 1:
The patent employs composite materials by combining lithium-cobalt composite oxide with lithium-nickel-cobalt-manganese composite oxide. This composite approach maintains excellent cycle characteristics while reducing the proportion of expensive cobalt, thereby resolving the contradiction between performance and cost
Solution Approach 2:
The patent applies local quality by using different composite oxide compositions in specific proportions (95:5 to 50:50 mass ratios) to optimize different aspects of battery performance locally, achieving cost-effective cycle characteristics through strategic material distribution
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 battery achieves high capacity and excellent cycle characteristics by optimizing the particle sizes of the composite oxides, ensuring stable performance over multiple charge/discharge cycles.
Implementation Method 1
lithium can be intercalated only up to the composition of LiC6
Implementation Method 2
silicon allows lithium to be intercalated up to the composition of Li4.4Si
Data Source
AI summary
The present invention has an object to provide a nonaqueous electrolyte secondary battery having high capacity and excellent cycle characteristics. A nonaqueous electrolyte secondary battery according to an embodiment of the present invention includes a positive electrode plate containing a lithium-cobalt composite oxide and a lithium-nickel-cobalt-manganese composite oxide (LiaNibCocMn1-b-cO, 0.9<a≦1.2, 0<b≦0.8, 0<c≦0.9) having an average primary particle size of 1.2 μm to 5.0 μm and a negative electrode which contains one of silicon (Si) and silicon oxide (SiOx, 0.5≦x<1.6) and which includes a negative electrode active material that stores and releases lithium ions.