Lithium-Ion Cathode Composite for High Voltage and Rate Performance
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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 layered structure that changes to a spinel structure within a specific electric potential range, enhancing discharge operating voltage and initial rate characteristics while maintaining high discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
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 insufficient
Solution Approach 1:
The patent uses a composite material system consisting of a cathode composition containing a spinel structure compound (LiMn2O4 or doped variants) combined with other lithium-containing transition metal oxides. This composite structure leverages the high ionic conductivity and stable framework of the spinel phase to improve both discharge capacity and rate characteristics, while the additional compounds contribute to overall battery performance and stability.
Solution Approach 2:
The patent systematically varies compositional parameters including the ratios of different metal elements (Li, Mn, and doping elements like Ni, Co, Al, Mg, Zn, Ca, Sr, Ba) in the spinel structure, as well as the proportion of spinel compound to other cathode materials. By optimizing these parameters, the invention achieves enhanced discharge capacity and improved initial rate characteristics simultaneously.
2Use of energy by moving object
If the discharge operating voltage is increased, then the energy density improves, but the initial rate characteristic deteriorates
Solution Approach 1:
The spinel structure compound serves as a critical component in the composite cathode material system. The spinel phase provides excellent ionic conductivity and structural stability that enable the battery to maintain high discharge operating voltage while simultaneously supporting high rate discharge characteristics, thus resolving the trade-off between voltage and rate performance.
Solution Approach 2:
The patent introduces doping elements at specific lattice positions within the spinel structure to locally enhance ionic conductivity and electronic properties. This local modification of the crystal structure allows different regions of the cathode material to perform specialized functions, with doped spinel regions providing high-rate capability while maintaining overall high operating voltage.
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 active material achieves excellent discharge operating voltage and initial rate characteristics while maintaining high discharge capacity, suitable for lithium ion secondary batteries in vehicles and portable devices.
Implementation Method 1
having a layered structure which changes to a spinel structure within an electric potential range of not less than 4.3V and not more than 4.8V
Implementation Method 2
a positive electrode active material containing a solid solution lithium-containing transition metal oxide (A) and a lithium-containing transition metal oxide (B)
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 0.2≦̸a≦̸0.7, 0.1≦̸d≦̸0.4, a+b+c+d=1.5, 1.1≦̸a+b+c≦̸1.35, and 0<b/a<1); 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).