Layered Lithium-Metal Oxide Cathode for Capacity-Voltage Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face challenges in simultaneously increasing charge capacity and maintaining discharge voltage, as Li2NiO2 has poor reversibility, leading to reduced battery capacity and voltage when used in the positive electrode.
Innovation Solution
A lithium-metal composite oxide with a specific formula xLiyMO2-(1-x)LizMO2, where 0<x<0.4, 1.5≤y≤2.5, and 0.9≤z≤1.5, is used as the positive electrode active material, featuring a layer structure with Li elements coordinated at tetrahedral and octahedral sites, along with a negative electrode active material comprising Si, SiC, SiO, Sn, SnO2, Sb, or Ge, to enhance both charge capacity and discharge voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li2NiO2 is contained in the positive electrode to supply sufficient Li ions during charging, then charge capacity is improved, but discharge voltage is reduced due to poor reversibility of Li ion absorption and release
Solution Approach 1:
The patent modifies the chemical composition parameters of the positive electrode active material by controlling the ratios of Ni, Mn, and Li elements, and by precisely controlling the Li content to exceed the stoichiometric amount. This parameter optimization enables the material to achieve both high charge capacity and maintained discharge voltage by improving Li ion reversibility
Solution Approach 2:
The patent uses a composite oxide material with specific multi-element composition (Ni-rich layered structure with controlled Li excess) to combine the advantages of high capacity with improved voltage characteristics, resolving the trade-off between charge capacity and discharge voltage
2Quantity of substance
If charge capacity is increased, then more Li ions are supplied to the negative electrode, but discharge voltage is reduced
Solution Approach 1:
The patent optimizes the chemical composition parameters including Ni content (0.7-0.9), Mn content (0.1-0.3), and Li content (exceeding stoichiometric amount), along with controlling particle size (3-15 μm) and specific surface area (0.5-2.0 m²/g) to achieve both high charge capacity and maintained discharge voltage through improved Li ion reversibility
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
This configuration improves both charge capacity and discharge voltage of the battery, balancing capacity maintenance and voltage performance.
Implementation Method 1
Li2NiO2 has poor reversibility with regard to absorption and release of Li ions
Implementation Method 2
non-aqueous electrolyte secondary batteries are widely in use in which the battery is charged and discharged by moving Li ions or the like between a positive electrode and a negative electrode
Data Source
AI summary
This positive electrode active material contains a lithium metal composite oxide represented by general formula xLiyMO2-(1-x)LizMO2 (where 0<x<0.4, 1.5≤y≤2.5, 0.9≤z≤1.5, and M is one or more elements selected from the group consisting of transition metals and Al, Si, Sn, Ge, Sb, Bi, Mg, Ca, and Sr). The lithium metal composite oxide has a layered structurer, and has, in a single secondary particle, Li occupying an oxygen tetrahedral site and Li occupying an oxygen octahedral site.