Lithium Transition Metal Oxide Composite for High Rate Battery Cathodes
Solution Overview
Problem
Conventional lithium ion batteries using cathode compositions with O3 crystal structure do not achieve sufficient discharge capacity, discharge operating voltage, and initial rate characteristics.
Innovation Solution
A positive electrode active material comprising a solid solution lithium-containing transition metal oxide (A) and lithium-containing transition metal oxide (B) with specific compositional formulas, allowing for a spinel structure change ratio and maintaining high discharge capacity and initial rate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a cathode composition with O3 crystal structure is used, then the battery can operate, but the discharge capacity, discharge operating voltage and initial rate characteristic are not sufficient
Solution Approach 1:
The patent uses a composite material system consisting of a core substance (lithium-containing transition metal oxide with O3 crystal structure) and a coating substance (amorphous lithium phosphate). This composite structure allows the core to provide high discharge capacity while the coating layer improves initial rate characteristics by facilitating lithium ion transport and stabilizing the electrode surface.
Solution Approach 2:
The patent optimizes specific parameters including the coating thickness (0.1-10 μm), the composition ratios of metal elements (Ni, Co, Mn) in the core substance, and the charge-discharge cycle conditions. These parameter changes enable the electrode to achieve both high discharge capacity and improved initial rate characteristics.
2Use of energy by moving object
If the discharge capacity is increased, then more energy is stored, but the discharge operating voltage and initial rate characteristic deteriorate
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrode material, specifically applying an amorphous lithium phosphate coating with controlled thickness and composition. This parameter change enables the electrode to maintain high energy storage capacity while improving the rate at which lithium ions can be exchanged, thus enhancing initial rate characteristics.
3Ease of manufacture
If a conventional cathode composition is used, then the manufacturing process is simple, but the discharge operating voltage is insufficient
Solution Approach 1:
The patent employs a composite material structure where a conventional lithium-containing transition metal oxide core is coated with amorphous lithium phosphate. This composite approach maintains the simplicity of manufacturing the core material while the added coating layer enhances the discharge operating voltage through improved electrochemical performance.
Solution Approach 2:
The patent applies a preliminary coating treatment to the cathode material before battery assembly. This preliminary action of coating the core substance with amorphous lithium phosphate prepares the electrode surface to achieve higher discharge operating voltage without complicating the overall manufacturing 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 proposed solution achieves excellent discharge operating voltage and initial rate characteristics while maintaining high discharge capacity, particularly within the electric potential range of 3.0V to 4.5V, suitable for lithium ion secondary batteries in vehicles and portable devices.
Implementation Method 1
a solid solution lithium-containing transition metal oxide (A) represented by a compositional formula (1) Li1.5[NiaCobMnc[Li]d]O3
Implementation Method 2
the choice of each active material is critically important... Liy[M1(1-b)Mnb]O2 or (b) Lix[M1(1-b)Mnb]O1.5+c
Data Source
AI summary
A positive electrode active material is provided to contain: a solid solution lithium-containing transition metal oxide (A) represented by Li1.5[NiaCobMnc[Li]d]O3 (where a, b, c and d satisfy the relations of 0.1≦d≦0.4, a+b+c+d=1.5, and 1.1≦a+b+c≦1.4.); and a lithium-containing transition metal oxide (B) represented by Li1.0Nia′Cob′Mnc′O2 (where a′, b′ and c′ satisfy the relation of a′+b′+c′=1.0.).