Battery Electrolyte Double Salts for High-Nickel Cycle Life
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Solution Overview
Problem
Secondary batteries with high-nickel ternary positive electrodes suffer from reduced cycle life due to lithium-nickel intermixing and poor stability of the solid electrolyte interphase (SEI) films, leading to co-intercalation of solvent molecules and damage to electrode materials.
Innovation Solution
An electrolyte comprising an organic solvent and an electrolyte salt with an alkali metal double salt containing lithium ions and other alkali metal ions, such as sodium and potassium, which are intercalated into lithium sites to stabilize the layered positive electrode structure and enhance the composition of the SEI film, preventing solvent co-intercalation and improving cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel ternary positive electrode materials are used to increase energy density, then the energy density is improved, but the cycle life is reduced due to lithium-nickel intermixing
Solution Approach 1:
Alkali metal ions (Na+, K+) serve as intermediary elements that occupy lithium sites in the layered positive electrode structure. These intermediary ions prevent direct lithium-nickel intermixing by blocking the migration pathways, thereby maintaining structural stability and extending cycle life while preserving high energy density
Solution Approach 2:
The invention changes the ionic composition parameter of the electrolyte by introducing alkali metal double salts containing both lithium ions and other alkali metal ions (Na+, K+). This parameter change modifies the SEI film composition and the electrode interface chemistry, reducing lithium-nickel intermixing and improving cycle life
2Device complexity
If conventional lithium salt electrolytes are used, then the electrolyte formulation is simple, but the SEI film has low organic lithium content leading to solvent co-intercalation and electrode material damage
Solution Approach 1:
The electrolyte uses composite lithium salts formed by double salts containing both lithium ions and other alkali metal ions (Na+, K+). This composite approach creates a more stable SEI film with higher organic lithium content that prevents solvent co-intercalation, improving electrode material stability while maintaining reasonable formulation complexity
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 alkali metal double salts in the electrolyte enhances the stability of the SEI film, reduces Li/Ni intermixing, and extends the cycle life of secondary batteries without introducing additional impurities or causing side reactions.
Implementation Method 1
other alkali metal ions (such as sodium ions and potassium ions) ... can be intercalated into some of the lithium sites of a layered positive electrode during the initial discharging process
Implementation Method 2
solid electrolyte interphase (SEI) films formed by conventional lithium salt electrolytes and located on the surfaces of electrodes
Data Source
AI summary
The present application relates to an electrolyte, comprising an organic solvent and an electrolyte salt dissolved in the organic solvent, wherein the electrolyte salt comprises an alkali metal double salt, the alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions. The present application also relates to a corresponding secondary battery, battery module, battery pack and power consuming device. In the electrolyte, an alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions is used in an electrolyte salt, such that the cycling performance of a secondary battery can be effectively improved and the cycle life of the secondary battery can be prolonged without introducing additional impurities and causing side reactions.