Multiple Electrolyte Lithium Battery Cell Design
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Solution Overview
Problem
Lithium batteries face challenges in finding an electrolyte that is chemically and electrochemically stable with both anode and cathode materials due to the extreme reactivity of lithium, requiring compromises that affect overall cell performance, especially in high voltage applications where a single electrolyte cannot support the voltage range.
Innovation Solution
The use of different electrolytes optimized for each electrode in a lithium battery, with a reductively stable dry polymer electrolyte at the anode and an oxidatively stable dry polymer electrolyte at the cathode, allowing for independent optimization of each electrode without compromising the cell's overall operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electrolyte is used in the battery cell, then the device complexity is reduced, but the electrochemical stability and performance are compromised due to the extreme reactivity of lithium and inability to meet both anode and cathode requirements
Solution Approach 1:
The battery cell is divided into separate electrolyte zones: a first electrolyte in contact with the anode and a second electrolyte in contact with the cathode. This segmentation allows each electrolyte to be independently optimized for its respective electrode's electrochemical requirements, resolving the contradiction between electrochemical stability and device complexity.
Solution Approach 2:
Different electrolyte compositions are used in different locations within the cell based on local electrochemical needs. The anode-side electrolyte is selected for reductive stability, while the cathode-side electrolyte is selected for oxidative stability, allowing each region to have the optimal electrolyte properties for its specific function.
2Power
If a single electrolyte is used, then the manufacturing process is simplified, but the voltage range and cycling efficiency are limited due to inability to support high voltage applications
Solution Approach 1:
The electrolyte system is divided into two separately fillable zones, allowing the first electrolyte to be optimized for high voltage/cathode compatibility and the second for anode compatibility. This segmentation enables achievement of high voltage range while managing manufacturing complexity through systematic filling procedures.
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 approach results in high voltage electrochemical cells with improved cycling efficiency, minimal impedance increase, and maintained capacity over many cycles, overcoming limitations of conventional electrolytes in lithium-ion batteries.
Implementation Method 1
a reductively stable dry polymer electrolyte at the anode
Implementation Method 2
an oxidatively stable dry polymer electrolyte at the cathode
Data Source
AI summary
Electrode assemblies for use in electrochemical cells are provided. The negative electrode assembly comprises negative electrode active material and an electrolyte chosen specifically for its useful properties in the negative electrode. These properties include reductive stability and ability to accommodate expansion and contraction of the negative electrode active material. Similarly, the positive electrode assembly comprises positive electrode active material and an electrolyte chosen specifically for its useful properties in the positive electrode. These properties include oxidative stability and the ability to prevent dissolution of transition metals used in the positive electrode active material. A third electrolyte can be used as separator between the negative electrode and the positive electrode.