Composite Cathode Material for High Voltage Lithium Ion Batteries
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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 a lithium-containing transition metal oxide (B), represented by specific compositional formulas, which undergoes structural changes within a specific electric potential range to enhance discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a cathode composition with O3 crystal structure is used, then the battery can be operated at high voltage, but the discharge capacity and initial rate characteristic are insufficient
Solution Approach 1:
The invention uses a composite cathode material consisting of Li2MnO3 and Li1-xMxMn2-xO4 components. Li2MnO3 provides high voltage operation through its layered structure, while Li1-xMxMn2-xO4 contributes to discharge capacity and rate characteristics through its spinel structure. The synergistic combination resolves the contradiction between high voltage and sufficient discharge capacity.
Solution Approach 2:
The invention changes the compositional parameters by controlling the ratio of Li2MnO3 to Li1-xMxMn2-xO4 (where 0 < x ≤ 0.5 and M is Ni, Co, or Zn). By optimizing these compositional parameters, the battery achieves both high discharge operating voltage and sufficient discharge capacity, resolving the technical contradiction.
2Device complexity
If a cathode composition with O3 crystal structure is used, then the battery structure is simplified, but the initial rate characteristic deteriorates
Solution Approach 1:
The composite structure of Li2MnO3 (layered) and Li1-xMxMn2-xO4 (spinel) provides excellent initial rate characteristics due to the dual-phase architecture. The spinel component facilitates rapid lithium ion diffusion, improving rate capability without significantly increasing structural complexity.
3Quantity of substance
If the cathode material undergoes phase transformation to spinel structure, then the discharge capacity improves, but the structural stability deteriorates
Solution Approach 1:
The invention controls the composition parameter x in Li1-xMxMn2-xO4 where 0 < x ≤ 0.5. This compositional control allows the material to undergo beneficial phase transformations that improve discharge capacity while maintaining structural stability through the presence of stabilizing metal elements (Ni, Co, or Zn).
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 achieves excellent discharge operating voltage and initial rate characteristics while maintaining high discharge capacity, particularly in lithium ion secondary batteries used for vehicle drive power supplies and portable devices.
Implementation Method 1
the solid solution lithium-containing transition metal oxide (A) has: a layered structure portion that changes into a spinel structure by performing charge or charge-discharge within an electric potential range of not less than 4.3V and not more than 4.8V; and a layered structure portion that does not change
Data Source
AI summary
[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 a+b+c+d=1.5, 0.1<d≦0.4, 1.1≦a+b+c<1.4, 0.2≦a≦0.7 and 0<b/a<1); and a lithium-containing transition metal oxide (B) represented by LiMXMn2−XO4 (where M represents Cr or Al, and x satisfies the relation of 0≦x<2).