Lithium Battery Electrolyte Additives for Nickel-Rich Cathode Stability
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Solution Overview
Problem
The degradation rate of lithium secondary batteries, particularly those with high-capacity cathodes like layered nickel-rich LiNi1-x-yCoxMnyO2, is accelerated by residual lithium components promoting electrolyte decomposition and interface reactivity, leading to reduced charging and discharging performance.
Innovation Solution
Incorporation of a cathode film additive agent, (4-allyl-2-methoxyphenoxy) trimethylsilane, and an anode film additive agent, such as vinylene carbonate or LiPO2F2, into the electrolyte to form protective layers on the cathode and anode surfaces, mitigating electrolyte decomposition and enhancing electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity cathode materials like layered nickel-rich LiNi1-x-yCoxMnymO2 are used to increase energy density, then the cathode capacity is improved, but the residual lithium components on the cathode surface promote electrolyte decomposition and increase interface reactivity, leading to accelerated degradation and reduced lifespan
Solution Approach 1:
The patent introduces a film-forming additive as an intermediary substance between the high-capacity cathode and the electrolyte. This additive preferentially reacts with residual lithium components on the cathode surface to form a stable protective film, mediating the harmful interaction between the cathode and electrolyte while preserving the high capacity benefits of nickel-rich cathode materials
Solution Approach 2:
The film-forming additive performs preliminary protective action by forming a stable interface film before the electrolyte can decompose. This pre-formed protective layer prevents subsequent electrolyte decomposition and interface reactions that would otherwise accelerate degradation, thereby extending battery lifespan while maintaining high cathode capacity
2Quantity of substance
If the charging voltage is increased to improve cathode capacity, then the energy density is improved, but the interface reactivity with the electrolyte increases, leading to faster degradation of charging and discharging performance
Solution Approach 1:
The protective film formed by the film-forming additive acts as an intermediary layer that stabilizes the cathode-electrolyte interface. This intermediary film reduces interface reactivity even at high charging voltages, allowing the system to achieve high energy density while maintaining stable charging and discharging performance without accelerated degradation
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 protective layers improve the lifespan and output characteristics of lithium secondary batteries by reducing unwanted side reactions and maintaining stability at high temperatures.
Implementation Method 1
the cathode film additive agent is decomposed first on the surface of the cathode and anode to form CEI and SEI layers
Implementation Method 2
the cathode film additive agent is decomposed first on the surface of the cathode and anode to form CEI and SEI layers
Implementation Method 3
Electrical energy is generated and stored by a change in a chemical potential when lithium ions are intercalated/deintercalated in the cathode and the anode
Data Source
AI summary
The present disclosure provides an electrolyte for a lithium secondary battery capable of improving the lifespan characteristics and output characteristics of a high capacity lithium secondary battery and a lithium secondary battery including the same. The electrolyte for a lithium secondary battery, according to an embodiment of the present disclosure, is an electrolyte for a lithium secondary battery including a lithium salt, a solvent, and a functional additive agent, in which the functional additive agent includes a cathode film additive agent, (4-allyl-2-methoxyphenoxy) trimethylsilane, represented by the following formula: