Cathode-Electrolyte Composition for High-Temperature Li-Ion Cycling
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Solution Overview
Problem
Existing lithium-ion batteries face challenges in achieving high volumetric energy density, long cycle life, and high-temperature cycling stability, with doping elements improving structural stability but reducing capacity, and conventional additives limiting cycling performance at both room temperature and high temperatures.
Innovation Solution
Incorporating a positive electrode active material doped with La, Y, or Nb, and an electrolyte containing specific compounds represented by formulas (I) and (II), which form a stable interface film and SEI to enhance mechanical strength and block side reactions, thereby improving cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a doping element is added to the positive electrode material to enhance structural stability, then the high-temperature cycling retention rate increases, but the capacity of the material significantly reduces
Solution Approach 1:
The patent optimizes the doping content of element A to a specific range (0.01-2 mass%, with preferred ranges of 0.05-1 mass% and most preferably 0.1-0.5 mass%) to achieve the best balance between structural stability and capacity. This precise parameter control resolves the contradiction by finding the optimal doping level that provides sufficient structural reinforcement without excessive capacity loss.
Solution Approach 2:
The patent uses composite positive electrode materials containing LiCoO2 or LiNi0.8Co0.1Mn0.1O2 as the base material doped with element A (La, Y, or Nb). This composite structure combines the high capacity of the base material with the structural stability provided by the doping element, resolving the contradiction between capacity and cycling stability.
2Use of energy by moving object
If the focus is on achieving high volumetric energy density and portability, then the battery meets modern electronic product requirements, but the cycling stability and high-temperature performance become more difficult to ensure
Solution Approach 1:
The patent uses LiNi0.8Co0.1Mn0.1O2 (NMC 811) as the positive electrode material, which provides high volumetric energy density. By combining this high-capacity material with element A doping (0.01-2 mass%) and the electrolyte additive (0.01-2 mass%), the patent achieves both high energy density and improved cycling stability (70% or more retention after 500 cycles at 45°C), resolving the contradiction between energy density and cycling stability.
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 solution effectively enhances cycling performance at both room temperature and high temperatures, stabilizing the lattice structure and preventing coating layer detachment, thus improving the electrochemical device's durability.
Implementation Method 1
an electrolyte containing specific compounds represented by formulas (I) and (II), which form a stable interface film and SEI to enhance mechanical strength and block side reactions
Data Source
AI summary
An electrochemical device of this application includes a positive electrode, a negative electrode, and an electrolyte, where the positive electrode includes a positive electrode active material, the positive electrode active material includes element A, and element A is selected from at least one of La, Y, or Nb; based on a mass of the positive electrode active material, a mass percentage of element A is x %; the electrolyte includes a compound represented by formula (I); and based on a mass of the electrolyte, a mass percentage of the compound represented by formula (I) is a %.