Germanium Electrolyte Additive for High-Voltage NCM Battery Stability
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Solution Overview
Problem
Conventional lithium-ion batteries with lithium hexafluorophosphate-based electrolytes exhibit low oxidative stability, leading to electrolyte decomposition and degradation of cathode materials at high potentials, resulting in low cycle stability and battery life.
Innovation Solution
Incorporating a germanium organyl-based electrolyte additive into the electrolyte of lithium-ion batteries, specifically with lithium nickel manganese cobalt oxide (NCM) cathodes, enhances electrochemical stability and suppresses cathode material degradation by increasing lithiation/delithiation potential and forming a protective cathode-electrolyte interphase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium hexafluorophosphate-based electrolytes are used, then the battery can operate with standard components and manufacturing processes, but the electrolyte decomposes and cathode material degrades at high potentials above 4.5 V, resulting in low cycle stability
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates between the electrolyte and the cathode material. This additive preferentially reacts with the cathode surface to form a stable protective film, preventing direct contact and harmful reactions between the unstable electrolyte and cathode material, thereby resolving the contradiction between electrolyte composition stability and overall system reliability
Solution Approach 2:
The patent changes the chemical parameters of the electrolyte by introducing fluorinated cyclic carbonate compounds with specific molecular structures and properties. These parameter changes in the electrolyte composition enable the formation of stable interfacial films that raise the effective oxidative stability limit from 4.5 V to above 4.55 V, resolving the stability contradiction
2Quantity of substance
If the battery operates at high potentials above 4.5 V to increase energy density, then higher capacity is achieved, but electrolyte decomposition and cathode degradation occur, reducing battery life
Solution Approach 1:
The patent applies preliminary action by having the fluorinated cyclic carbonate additive react first with the cathode surface during initial cycles to form a stable protective film before the harmful decomposition reactions can occur. This pre-formed protective layer enables the battery to operate at high potentials (above 4.55 V) for extended periods without degradation, simultaneously achieving high energy density and long service life
Solution Approach 2:
The patent converts the potentially harmful high potential operation (which would normally cause decomposition) into a beneficial effect by using the fluorinated additive to create a stable interface. The high voltage operation, which would normally be detrimental, becomes beneficial for energy density while the protective film prevents the expected degradation, extending service life
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 use of germanium organyl-based additives significantly improves cycle stability and service life of lithium-ion batteries, reducing self-discharge and maintaining superior performance up to higher voltages, such as 4.55 V, while maintaining high Coulombic efficiency.
Implementation Method 1
forming a protective cathode-electrolyte interphase
Implementation Method 2
increasing lithiation/delithiation potential
Data Source
AI summary
A lithium battery including an anode having an active anode material, a cathode having an active cathode material. The cathode material includes lithium nickel cobalt manganese cobalt oxide (NCM). An electrolyte separates the anode and cathode. The electrolyte includes a solvent or solvent mixture and lithium hexafluorophosphate, and a germanium organyl-based electrolyte additive. Also disclosed are uses of the germanium organyl-based electrolyte additive in the lithium battery for enhancing one characteristic selected from the group consisting of reversible capacity, Coulombic efficiency, cyclic stability and combinations thereof.