Lithium Battery Cathode Composite Coating for Stability
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Solution Overview
Problem
Current cathode active materials for lithium secondary batteries face challenges in achieving high capacity, efficiency, and rate capability, with existing solutions either being expensive, difficult to synthesize, or limited in improving surface structure and stability.
Innovation Solution
A cathode active material with a composite coating layer containing Li3PO4, lithium metal oxide, and/or metal oxides, such as ZrO2, is applied to the surface of lithium intercalation compounds, which includes doping with metals like Mg, Ca, or Ti, to enhance ion conductivity and surface modification, thereby improving battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as cathode active material, then excellent electric conductivity, high battery voltage, and excellent cycle life are achieved, but high cost is incurred
Solution Approach 1:
The patent replaces expensive LiCoO2 with cheaper LiNiO2 as the cathode active material. Although LiNiO2 has synthesis difficulties and stability issues, the invention uses it as a cost-effective alternative to reduce battery cost while maintaining acceptable performance through optimized synthesis conditions
Solution Approach 2:
The patent employs composite cathode materials combining LiNiO2 with other materials to achieve both cost reduction and performance improvement. The composite structure allows leveraging the high capacity of LiNiO2 while mitigating its stability issues through interaction with complementary materials
2Quantity of substance
If LiNiO2 is used as cathode active material, then highest discharge capacity is achieved, but synthesis difficulty and stability issues occur
Solution Approach 1:
The patent optimizes synthesis parameters including temperature, time, and atmosphere to successfully manufacture LiNiO2. By carefully controlling these parameters, the invention overcomes the synthesis difficulties of LiNiO2 while achieving the desired high discharge capacity and structural stability
Solution Approach 2:
The patent employs advanced characterization techniques and computational methods to understand and control the synthesis process of LiNiO2, replacing traditional trial-and-error mechanical approaches with more precise scientific methods
3Reliability
If Mn based cathode active material is used, then thermal stability and low cost are achieved, but small capacity is the result
Solution Approach 1:
The patent combines Mn-based materials with Ni-based materials or other high-capacity materials to create composite cathodes. This merging allows the composite to inherit the thermal stability of Mn-based materials while gaining the high capacity characteristics of Ni-based materials
4Quantity of substance
If high voltage is applied to achieve high capacity, then energy density is improved, but residual lithium increases and swelling occurs
Solution Approach 1:
The patent applies surface coating to the cathode active material before battery operation. This coating layer acts as a protective barrier that prevents direct contact between the high-voltage electrolyte and the cathode surface, thereby preventing residual lithium formation and swelling while allowing high-voltage operation for high energy density
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 composite coating layer significantly enhances the battery's initial capacity, efficiency, and rate capability, while reducing residual lithium and suppressing swelling, leading to improved stability and performance at high voltages.
Implementation Method 1
A cathode active material for a lithium secondary battery having a surface on which a composite coating layer containing Li3PO4 and further containing a lithium metal oxide, a metal oxide, and/or a combination thereof, the lithium metal oxide or the metal oxide containing Zr, is coated
Implementation Method 2
a reaction with remaining Li does not occur
Data Source
AI summary
There are provided a cathode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery containing the same. The cathode active material for a lithium secondary battery includes: a compound reversibly intercalating and deintercalating lithium; and a coating layer positioned on at least a portion of a surface of the compound, wherein the coating layer is a composite coating layer containing Li3PO4 and further containing a lithium metal oxide, a metal oxide, and/or a combination thereof, the lithium metal oxide or the metal oxide containing Zr.