Carbon-Coated Spinel Cathode for High-Voltage Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries with LiMn2O4 have low energy density and suffer from electrolyte decomposition and manganese ion elution at high operating potentials, limiting their application in high voltage applications.
Innovation Solution
A cathode active material comprising particles of a spinel-type compound with a composition Li1+aMxMn2−xO4−zAz, where M is a metal and A is a mono- or dianion, coated with a carbon-based material to inhibit manganese elution and electrolyte side reactions, achieving an operating potential of 4.6V to 4.9V and improved energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the operating potential is increased to 4.6V or higher to improve energy density, then the energy density is improved, but the electrolyte decomposes and manganese ions suffer elution
Solution Approach 1:
A carbon-based coating layer is applied as an intermediary between the spinel-type compound and the electrolyte. This coating prevents direct contact and chemical reactions between the high-potential cathode material and the electrolyte, thereby preventing electrolyte decomposition while maintaining the high operating potential of 4.6V or higher needed for high energy density
Solution Approach 2:
The carbon-based coating layer serves as a protective intermediary that prevents manganese ion elution by blocking the direct interaction between the spinel-type compound surface and the electrolyte, thus maintaining structural integrity at high operating potentials
2Quantity of substance
If the operating potential is increased to 4.6V or higher to improve energy density, then the energy density is improved, but side reactions with the electrolyte reduce performance
Solution Approach 1:
The carbon-based coating acts as a protective intermediary barrier that physically separates the spinel-type compound from the electrolyte, preventing side reactions while allowing the system to operate at the high potential of 4.6V or higher necessary for achieving high energy density
3Reliability
If a carbon-based material is coated on the surface to inhibit manganese elution, then manganese elution is inhibited, but the surface area for electrochemical reaction may be reduced
Solution Approach 1:
The carbon-based coating is applied as a thin surface layer that provides protective functionality (inhibiting manganese elution) while minimizing the reduction in effective surface area. The coating modifies only the surface properties locally without significantly impacting the overall electrochemical active surface area
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 carbon-coated spinel-type compound exhibits stable charge/discharge cycles, increased reversible capacity, and reduced interfacial resistance, inhibiting manganese elution and electrolyte decomposition, thus enhancing the performance and longevity of high-voltage lithium secondary batteries.
Implementation Method 1
a carbon-based material present on surfaces of the particles of the spinel-type compound
Data Source
AI summary
Disclosed herein is a high voltage cathode active material and a method for preparing the same. The cathode active material includes particles of a spinel-type compound having a composition represented by Formula (1) and a carbon-based material present on surfaces of the particles of the spinel-type compound:Li1+aMxMn2−xO4−zAz (1)where −0.1≤a≤0.1, 0.3≤x≤0.8 and 0≤z≤0.1.