Polyvalent Organic Lithium Salt Electrolyte for High-Voltage Battery Stability
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Solution Overview
Problem
Non-aqueous secondary batteries using lithium-containing composite oxides as positive electrode active materials experience deterioration in charge/discharge cycle characteristics when charged to high voltages, particularly above 4.4V against lithium, due to reactions with the non-aqueous electrolyte.
Innovation Solution
Incorporating a non-aqueous electrolyte with a polyvalent organic lithium salt, such as LiSO3—Rf′—SO3Li, at specific concentrations (0.001 to 1 part by mass) to form a deposition film on the positive electrode, preventing direct contact with the electrolyte and reducing decomposition reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery is charged at a high voltage (4.4V or higher against lithium), then the energy density and capacity are improved, but the positive electrode active material reacts with the non-aqueous electrolyte causing deterioration of charge/discharge cycle characteristics
Solution Approach 1:
A coating layer comprising a polymer matrix and dispersed inorganic particles is introduced as an intermediary between the positive electrode active material and the non-aqueous electrolyte. This coating layer prevents direct contact and reaction between the electrolyte and active material, thereby suppressing deterioration of charge/discharge cycle characteristics while enabling high voltage charging (4.4V or higher) to achieve improved energy density
Solution Approach 2:
The coating layer is constructed as a composite material consisting of a polymer matrix (such as polyacrylonitrile, polyvinylidene fluoride, or carboxymethyl cellulose) with inorganic particles (such as aluminum oxide, aluminum hydroxide, or boehmite) dispersed within it. This composite structure provides both the protective barrier function and structural stability needed to maintain electrode integrity during high voltage operation
2Power
If the battery is charged to 4.5V or higher against lithium using lithium-containing composite oxide, then the potential and capacity are improved, but the reaction with non-aqueous electrolyte accelerates leading to significant deterioration of cycle characteristics
Solution Approach 1:
The coating layer acts as a protective intermediary that enables the positive electrode to operate at high potentials (4.5V or higher against lithium) without direct exposure to the non-aqueous electrolyte. This intermediary layer suppresses parasitic reactions while maintaining electrical conductivity, allowing the electrode to achieve high power output without sacrificing cycle life
Solution Approach 2:
The coating layer is applied as a thin film on the surface of the positive electrode active material particles. This thin film structure provides effective protection against electrolyte contact while minimizing the addition of inactive material, thus preserving the high potential and power characteristics of the underlying active material
3Quantity of substance
If the battery is charged to 5V or higher against lithium, then the capacity is significantly improved, but the deterioration of charge/discharge cycle characteristics becomes particularly significant due to electrolyte reaction
Solution Approach 1:
The coating layer serves as a robust intermediary barrier that enables ultra-high voltage charging (5V or higher against lithium) to achieve significantly improved capacity. The coating layer maintains its protective function even under the extreme conditions of high voltage charging, preventing the severe deterioration that would otherwise occur from direct electrolyte-active material reactions
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 polyvalent organic lithium salts in the electrolyte suppresses the deterioration of charge/discharge cycle characteristics, allowing the battery to maintain high capacity and cycle stability even when charged to 5V or higher.
Implementation Method 1
the polyvalent organic lithium salt is 0.001 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of all of the components of the non-aqueous electrolyte other than the polyvalent organic lithium salt
Implementation Method 2
the positive electrode active material reacts with a non-aqueous electrolyte, which may lead to the deterioration of the charge/discharge cycle characteristics of the battery
Data Source
AI summary
The non-aqueous secondary battery of the present invention comprises a positive electrode containing a lithium-containing composite oxide as an active material, a negative electrode, a separator, and a non-aqueous electrolyte. The non-aqueous electrolyte contains polyvalent organic lithium salt, and the content of the polyvalent organic lithium salt is 0.001 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of all of the components of the non-aqueous electrolyte other than the polyvalent organic lithium salt.