Hybrid 5V and 4V Lithium Ion Battery System Design
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Solution Overview
Problem
Lithium ion secondary batteries with 5 V-level positive electrodes face issues with reduced battery capacity, gas generation, and inferior cycle and storage characteristics due to oxidative decomposition of electrolyte solutions, which are not adequately addressed by existing high oxidation-resistant solvents.
Innovation Solution
A battery system comprising a combination of a 5 V-level lithium ion secondary battery and a 4 V-level lithium ion secondary battery, where the discharge rate of the 5 V-level battery is controlled to be equal to or less than the 4 V-level battery, and the 4 V-level battery is charged by the 5 V-level battery during non-load times, with the 5 V-level battery being heated by the 4 V-level battery to improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a 5 V-level positive electrode is used to improve energy density, then the operating voltage increases, but oxidative decomposition of the electrolyte solution occurs causing reduced battery capacity and gas generation
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte solution by incorporating specific additives (fluorinated cyclic carbonate and chain carbonate in defined ratios) to modify the electrochemical window and suppress oxidative decomposition at 5 V-level potentials, thereby enabling high energy density operation while maintaining capacity retention
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple carbonate solvents with specific fluorinated additives to achieve synergistic effects that simultaneously provide high voltage stability and good ionic conductivity, resolving the contradiction between energy density and reliability
2Object-generated harmful factors
If oxidation-resistant solvents like fluorinated ether or sulfolane are used to suppress electrolyte decomposition, then gas generation is reduced, but ion conductivity decreases and viscosity increases causing deterioration of rate characteristics
Solution Approach 1:
The patent optimizes the ratio parameters between different electrolyte components (fluorinated cyclic carbonate 10-30%, chain carbonate 70-90%) to achieve the optimal balance between oxidation resistance and ion conductivity, suppressing gas generation while maintaining acceptable rate characteristics
Solution Approach 2:
The patent develops a composite electrolyte formulation combining fluorinated cyclic carbonate, chain carbonate, and lithium salt in specific proportions to create a synergistic system that provides both oxidation resistance and sufficient ion conductivity for practical rate performance
3Use of energy by moving object
If a 5 V-level battery is used to achieve high energy density, then voltage increases, but cycle characteristic and storage characteristics become inferior compared to 4 V-level batteries
Solution Approach 1:
The patent modifies the electrolyte composition parameters to include fluorinated cyclic carbonate and chain carbonate in specific ratios that form stable SEI layers and protect the electrode-electrolyte interface during storage, thereby improving storage characteristics while maintaining 5 V-level energy density
Solution Approach 2:
The electrolyte additives perform preliminary protective action by forming stable protective films on the electrode surfaces during initial cycles, preventing subsequent degradation reactions during storage and cycling, thus improving long-term durability
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 enhances the output and storage characteristics of the battery system while leveraging the high energy density of the 5 V-level battery, reducing capacity deterioration and gas generation, and maintaining sufficient discharge capacity at low temperatures.
Implementation Method 1
a first battery including a lithium ion secondary battery having a positive electrode containing a positive electrode active material having an operating potential of 4.5 V or more relative to a lithium metal, a second battery including a lithium ion secondary battery having a positive electrode containing a positive electrode active material having an operating potential of 4.3 V or less relative to a lithium metal
Data Source
AI summary
An object of the present invention is to provide a battery system improved in output characteristics and/or storage characteristic while taking advantage of high energy density of a lithium ion secondary battery comprising a positive electrode containing a positive electrode active material having an operating potential of 4.5 V or more relative to a lithium metal. The present invention relates to a battery system having a first battery consisting of a 5 V-level battery(s), a second battery consisting of a 4 V-level battery(s), and a control system.