LiCoO2 Composite Positive Active Material for High Voltage Stability
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Solution Overview
Problem
The challenge in lithium-ion batteries is to increase capacity while maintaining cycling performance without causing structure collapse due to high voltage, as existing positive active materials face rapid capacity fade and reduced performance.
Innovation Solution
A positive active material with a specific composition and structure, featuring a bimodal particle size distribution and a lithium-cobalt molar ratio of 0.73-0.99, along with a coating layer, enhances specific capacity and voltage resistance, facilitating improved intercalation/deintercalation of lithium ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charge-discharge voltage is increased to increase battery capacity, then the capacity of the lithium-ion battery is improved, but the crystal structure collapse of positive active material occurs, resulting in rapid capacity fade and significant reduction in cycling performance
Solution Approach 1:
The patent employs a composite positive active material comprising LiCoO2 and Li1-x-yMxNiyO2 (where M is at least one of Al, Ti, Zr, or Y; and N is at least one of Al, Ti, Zr, or Y). This composite structure combines the high capacity characteristics of LiCoO2 with the structural stability of doped lithium metal oxides, enabling the material to maintain crystal structure integrity at high voltages while achieving enhanced capacity and cycling performance
Solution Approach 2:
The patent optimizes specific parameters including the lithium-cobalt molar ratio (0.85-0.95), particle size distribution (D50 of 12-18 μm with bimodal distribution), and doping element concentrations (0.01≤x≤0.05, 0.01≤y≤0.05). These parameter adjustments enable the material to achieve both high capacity and structural stability under high voltage conditions, resolving the contradiction between capacity improvement and cycling performance maintenance
2Quantity of substance
If the charge-discharge voltage is increased to increase battery capacity, then the capacity of the lithium-ion battery is improved, but the crystal structure collapse of positive active material occurs, resulting in rapid capacity fade
Solution Approach 1:
The composite structure of LiCoO2 and Li1-x-yMxNiyO2 provides both high capacity and long-term capacity retention. The doped Li1-x-yMxNiyO2 component reinforces the crystal structure to prevent collapse during extended cycling, while the LiCoO2 component contributes high capacity, achieving both improved capacity and sustained capacity retention over time
Solution Approach 2:
The doping elements (M and N) are incorporated into the crystal structure in advance during material synthesis, creating a pre-stabilized structure that resists collapse during subsequent charge-discharge cycles. This preliminary structural reinforcement prevents the crystal structure collapse that would otherwise lead to rapid capacity fade
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 material achieves higher capacity and cycling performance, especially under high voltages, with a first-time charge-discharge efficiency of 97%-145% and improved energy density, by ensuring structural stability and efficient lithium ion intercalation.
Implementation Method 1
facilitating the increased capacity and cycling performance of a battery... efficient lithium ion intercalation
Implementation Method 2
at least a part of the outer surface of the positive active material is covered by a coating layer
Data Source
Figure 1A~2A
Figure 1B~6A
Figure 3A~5A
AI summary
A positive active material and an application thereof. A peak I and a peak II, either of which have 20 ranging from 17.8° to 19.5°, are present in an X-ray diffraction pattern of the positive active material. The positive active material is special for improving the capacity, energy density and cycling performance of a battery.