Li-Ion Cathode-Electrolyte Composition for High-Temperature Cycling
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Solution Overview
Problem
Lithium-ion batteries face challenges in high-temperature cycling and interval cycling performance due to issues such as gas production, decomposition of electrolyte components, and increased impedance, which affect their stability and efficiency.
Innovation Solution
The composition of the electrolyte and positive electrode active material is optimized by including ethylene carbonate, propylene carbonate, succinonitrile, and specific metal elements like Mg, Zr, or Al, with controlled mass percentages and particle sizes, to enhance high-temperature stability and compatibility, reducing gas production and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte composition is used, then the battery can operate normally, but gas production increases and cycling performance deteriorates at high temperature
Solution Approach 1:
The patent modifies the electrolyte composition parameters by incorporating specific ratios of cyclic carbonates (EC, PC) and chain carbonates (DMC, DEC), along with lithium difluorophosphate additive. This parameter optimization suppresses gas generation while maintaining high-temperature cycling stability, directly resolving the contradiction between reliability and harmful gas production.
Solution Approach 2:
The patent employs a composite electrolyte system combining multiple carbonate solvents (EC, PC, DMC, DEC) with lithium difluorophosphate additive. This composite formulation creates synergistic effects that reduce gas production and improve high-temperature cycling performance compared to single-component electrolytes.
2Reliability
If conventional electrolyte composition is used, then the battery can operate normally, but decomposition of electrolyte components occurs at high temperature
Solution Approach 1:
The patent optimizes the electrolyte composition parameters including the ratios of cyclic to chain carbonates and the concentration of lithium difluorophosphate additive. These parameter adjustments enhance the thermal stability of electrolyte components, preventing decomposition during high-temperature interval cycling while maintaining operational reliability.
Solution Approach 2:
The patent introduces lithium difluorophosphate as a sacrificial additive that preferentially reacts to form stable protective films on electrode surfaces. This additive consumes itself to protect the main electrolyte components from decomposition, thereby improving long-term high-temperature stability.
3Reliability
If conventional electrolyte composition is used, then the battery can operate normally, but impedance increases at high temperature
Solution Approach 1:
The patent adjusts the electrolyte composition parameters, particularly the balance between cyclic and chain carbonates and the lithium difluorophosphate content. These changes optimize ionic conductivity and reduce impedance growth during high-temperature cycling, thereby improving capacity retention while minimizing energy loss.
Solution Approach 2:
The lithium difluorophosphate additive performs preliminary action by forming stable solid electrolyte interphase (SEI) films on electrode surfaces before main electrolyte decomposition occurs. This preliminary film formation prevents subsequent impedance increase and capacity fade during high-temperature operation.
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
This configuration improves the high-temperature cycling and interval cycling performance of lithium-ion batteries by stabilizing the electrode structure, reducing polarization, and maintaining capacity retention and thickness stability under high-temperature conditions.
Implementation Method 1
The electrolyte includes ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN)... Based on a mass of the electrolyte, a mass percentage of SN is a %, a mass percentage of EC is b %, and a mass percentage of PC is c %
Implementation Method 2
the positive electrode active material includes metal element A, and the metal element A includes at least one of the following elements: Mg, Zr, or Al... Based on a mass of the positive electrode active material, a mass percentage of the metal element A is x %
Data Source
AI summary
An electrochemical apparatus includes a positive electrode and an electrolyte. The electrolyte includes ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN). The positive electrode includes a positive electrode active material, where the positive electrode active material includes metal element A, and the metal element A includes at least one of the following elements: Mg, Zr, or Al. Based on a mass of the electrolyte, a mass percentage of SN is a %, a mass percentage of EC is b %, and a mass percentage of PC is c %, where k=b/c, 1.25≤k≤6, and a/k≥0.2. Based on a mass of the positive electrode active material, a mass percentage of the metal element A is x %, where 0.01≤x≤1. The foregoing electrochemical apparatus exhibits excellent high-temperature cycling performance and high-temperature interval cycling performance.