Composite Cathode Material for High-Rate Battery Stability
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in achieving both high-rate charge-discharge cycle performance and safety when using lithium-nickel-cobalt-manganese complex oxides and spinel lithium manganese oxides as positive electrode active materials, failing to meet the requirements for modern mobile electronic devices and hybrid electric vehicles.
Innovation Solution
A nonaqueous electrolyte secondary battery is developed using a mixture of tungsten- and zirconium-modified lithium nickel-cobalt-manganese oxide and spinel lithium manganese oxide in a specific proportion as the positive electrode active material, combined with a nonaqueous electrolyte containing a particular ratio of dimethyl carbonate and cyclic carbonate, which suppresses deteriorative reactions and structural collapse, enhancing safety and cycling characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-containing nickel oxide active material is used to achieve high theoretical capacity and high charge-discharge potential, then capacity is improved, but thermal stability deteriorates
Solution Approach 1:
The patent uses a composite positive electrode active material consisting of lithium-containing nickel oxide (Li1+xNi1-yMzO2) combined with spinel lithium-containing manganese oxide (LiMn2-yM1yO4). This composite structure allows the nickel oxide component to provide high capacity while the manganese oxide component provides thermal stability, resolving the contradiction between capacity and thermal stability.
Solution Approach 2:
The patent introduces different metal elements (M1, M2, M3) at specific positions in the crystal structure to locally enhance properties. For example, M1 in the spinel structure and M2, M3 in the lithium-containing nickel oxide provide localized structural stability and suppress harmful reactions, allowing the bulk material to maintain high capacity characteristics.
2Stability of the object's composition
If lithium-containing manganese oxide active material is used to achieve low cost and excellent thermal stability, then safety is improved, but theoretical capacity deteriorates
Solution Approach 1:
The patent creates a composite where lithium-containing manganese oxide (providing thermal stability and safety) is combined with lithium-containing nickel oxide (providing high capacity). The synergistic effect allows the battery to achieve both safety and high capacity, overcoming the limitation of manganese oxide's low theoretical capacity.
Solution Approach 2:
The patent modifies the composition parameters of lithium-containing manganese oxide by introducing metal elements M1, M2, and M3, and adjusting their ratios according to specific formulas. This parameter optimization enhances the capacity and electrochemical performance of manganese oxide while preserving its thermal stability.
3Reliability
If spinel lithium manganese oxide is mixed with nickel oxide active material to improve safety performance, then safety is improved, but capacity and high-temperature storage performance deteriorate
Solution Approach 1:
The patent precisely controls the composition parameters including the ratio of lithium-containing nickel oxide to spinel lithium-containing manganese oxide (95:5 to 50:50 by mass), the content of metal elements M1, M2, M3, and the stoichiometric ratios in the formulas. This parameter optimization ensures that safety is improved while capacity and high-temperature storage performance are maintained.
Solution Approach 2:
The patent introduces specific metal elements (M2, M3) at controlled concentrations (0 < x ≤ 0.1, 0 < y ≤ 0.1) in the lithium-containing nickel oxide structure to locally suppress manganese elution and structural collapse, thereby maintaining high capacity and cycle performance while achieving improved safety through the composite structure.
4Reliability
If large amounts of lithium manganese oxide are added to improve safety, then safety is improved, but high-rate charge-discharge cycle performance deteriorates
Solution Approach 1:
The patent optimizes the content ratio of spinel lithium-containing manganese oxide to lithium-containing nickel oxide within 5:95 to 50:50 by mass, and controls the metal element contents (x, y, z) to satisfy specific inequalities. This parameter optimization ensures that sufficient manganese oxide is present to suppress manganese elution and improve safety, while maintaining enough nickel oxide to preserve high-rate charge-discharge cycle performance.
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 solution effectively improves high-rate charge-discharge cycling characteristics and safety by preventing manganese elution and structural collapse, ensuring reliable performance and safety in lithium nickel-cobalt-manganese oxide-based batteries.
Implementation Method 1
lithium transition metal complex oxides represented by LiMO2 (where M is at least one of Co, Ni, and Mn) capable of reversibly absorbing and desorbing lithium ions
Implementation Method 2
a nonaqueous electrolyte including a nonaqueous solvent and a solute
Data Source
AI summary
[Problem] To provide a nonaqueous electrolyte secondary battery exhibiting superior stability characteristics and having charge/discharge characteristics exhibiting a high-rate discharge stroke, even when a lithium-nickel-cobalt manganate and a spinel-type lithium manganate are used as the positive electrode active material. [Solution] A mixture having a specific ratio of a tungsten- and zirconium-modified lithium-nickel-cobalt manganate and a spinel-type lithium manganate is used as the positive electrode active material. Furthermore, a nonaqueous electrolyte having a specific ratio of the content of dimethyl carbonate and the content of a cyclic carbonate is used.