Aluminum-Coated Manganese Cathodes for Low-Temperature Cycle Stability
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Solution Overview
Problem
Conventional nonaqueous electrolyte energy storage devices experience a significant increase in DC resistance and decrease in discharge capacity at low temperatures, particularly after repeated charge-discharge cycles, due to deterioration of the positive electrode, which affects their cycle performance.
Innovation Solution
A nonaqueous electrolyte energy storage device is developed with a positive electrode containing manganese-containing active material particles coated with aluminum, and a nonaqueous electrolyte featuring a specific salt structure, which stabilizes the protective film and maintains its effectiveness over long charge-discharge cycles, reducing DC resistance and enhancing capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal compound coating is applied to the positive active material surface, then high capacity and cycle durability at high temperatures are achieved, but DC resistance increases significantly at low temperatures after charge-discharge cycles
Solution Approach 1:
The invention changes the chemical composition parameters of the electrolyte by introducing a specific additive (formula 1) with particular structural characteristics. This additive modifies the protective film properties through chemical interaction, transforming the film's electrical resistance characteristics at low temperatures while preserving its protective function at high temperatures
Solution Approach 2:
The electrolyte additive acts as an intermediary substance that mediates between the metal compound coating and the electrolyte solution. It forms a modified protective film that serves as an intermediate layer, improving the interface properties between the electrode and electrolyte, thereby reducing DC resistance at low temperatures without compromising high-temperature stability
2Quantity of substance
If conventional electrolytes are used with metal compound coated electrodes, then initial capacity is maintained, but capacity retention ratio decreases significantly after extended charge-discharge cycles
Solution Approach 1:
The electrolyte additive performs preliminary action by forming a stabilized protective film during initial charge-discharge cycles. This pre-formed film prevents subsequent deterioration of the electrode material, maintaining capacity retention over extended cycling. The additive prepares the electrode-electrolyte interface in advance to resist degradation during long-term operation
Solution Approach 2:
The electrolyte additive acts as a consumable component that is gradually consumed during initial cycles to form the protective film. This sacrificial additive replaces the need for inherently stable but less effective conventional electrolytes, providing long-term capacity retention through controlled initial decomposition and film formation
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 solution results in a low rate of increase in DC resistance and high capacity retention ratio at low temperatures, improving the overall cycle performance and stability of the energy storage device.
Implementation Method 1
a positive electrode containing manganese-containing positive active material particles in which aluminum is present at least on a surface
Implementation Method 2
a nonaqueous electrolyte containing a salt represented by the following formula (1)... stabilizes the protective film and maintains its effectiveness over long charge-discharge cycles
Data Source
Figure 1~2
AI summary
One aspect of the present invention is a nonaqueous electrolyte energy storage device including a positive electrode containing manganese-containing positive active material particles in which aluminum is present at least on a surface, and a nonaqueous electrolyte containing a salt represented by the following formula (1). Another aspect of the present invention is a method of producing a nonaqueous electrolyte energy storage device, including producing a positive electrode containing manganese-containing positive active material particles in which aluminum is present at least on a surface, and providing a nonaqueous electrolyte containing a salt represented by the following formula (1): wherein R1 is a hydrogen atom, a halogen atom, or an organic group, Mm+ is an alkali metal cation, an alkaline earth metal cation, or an onium cation. m is an integer equivalent to the number of valence of a cation represented by Mm+. when m is 2 or more, a plurality of R1s are each independently as defined above.