High-Nickel Li-Ion Electrode Composition for Low-Resistance Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing demand for lithium ion secondary batteries for vehicles has led to concerns about cobalt depletion, and reducing cobalt content in positive electrode active materials results in significant increases in initial resistance and storage time resistance.
Innovation Solution
A lithium ion secondary battery design featuring a positive electrode with a lithium-transition metal complex oxide having a high nickel content and a layered structure, coated with a tungsten or phosphorus compound, and a negative electrode with a carbon material and silicon-containing material, optimizing the nickel content and silicon ratio to minimize resistance increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the containing rate of Co in the positive electrode active material is decreased, then cobalt depletion is addressed and cost is reduced, but initial resistance increases significantly and resistance at storing time increases
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by specifying a lithium nickel manganese oxide composite with Ni containing rate of 75-95 mol% and Mn containing rate of 5-25 mol%, optimizing the ratio to achieve low resistance while minimizing cobalt content
Solution Approach 2:
The patent uses a composite material approach by creating a lithium nickel manganese oxide composite (LiNi_xMn_yO2 where x=0.75-0.95, y=0.05-0.25) that combines the advantages of nickel (high capacity) and manganese (structural stability) to achieve low resistance without cobalt
2Reliability
If the containing rate of Ni in the lithium-transition metal complex oxide is increased to maintain performance, then resistance stability is improved, but cobalt content must be precisely controlled
Solution Approach 1:
The patent defines specific parameter ranges for Ni (75-95 mol%) and Mn (5-25 mol%) containing rates, along with stoichiometric ratios (0.95≥x+y≥1.05), to optimize performance while simplifying the control process through clear boundaries
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a herein disclosed lithium ion secondary battery, a positive electrode active material includes a lithium-transition metal complex oxide, containing Li, Ni, and Mn and being formed in a layered structure, and includes a covering part, a lithium-transition metal complex oxide has a Ni containing rate being equal to or more than 75 mol% with respect to the total of metal elements other than the Li and is a secondary particle consisted by a primary particle being aggregated, and the covering part contains a tungsten compound and/or a phosphorus compound. On the other hand, a negative electrode active material contains a carbon material and a Si containing material, and a containing ratio of a Si element in the negative electrode active material is equal to or more than 5 mass% and not more than 10 mass% when a total amount of the negative electrode active material is treated as 100 mass%.