Positive Electrode Mix with Irreversible Additive for Battery Energy Density
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Solution Overview
Problem
Secondary batteries, particularly lithium secondary batteries, face challenges due to lower irreversible efficiency of negative electrodes, leading to excessive addition of negative and positive active materials, which negatively affects energy density.
Innovation Solution
Incorporating an irreversible additive with an operation voltage of 1.0 V to 2.5 V, such as lithiated lithium titanium oxide or lithium molybdenum sulfide, into the positive electrode mix to decrease irreversible efficiency and enhance conductivity, thereby improving the conductive network composition of the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative electrode active materials are added in excessively large amounts to compensate for lower irreversible efficiency, then irreversible efficiency of negative electrode is improved, but battery energy density deteriorates
Solution Approach 1:
The patent applies preliminary anti-action by adding an irreversible additive to the positive electrode that proactively consumes lithium during initial charging, preventing the positive electrode from having excessively high irreversible efficiency that would mismatch the negative electrode. This preliminary adjustment balances the irreversible efficiencies of both electrodes without requiring excessive active material amounts, thereby maintaining high energy density while achieving reliable irreversible efficiency balance.
2Reliability
If positive electrode active materials are added in excessively large amounts to adjust irreversible capacities, then irreversible efficiency matching is improved, but battery energy density deteriorates
Solution Approach 1:
The patent applies parameter changes by introducing an irreversible additive with specific electrochemical properties (operation voltage 1.0-2.5 V vs Li, specific capacity 200-400 mAh/g) to the positive electrode. This changes the irreversible efficiency parameter of the positive electrode from excessively high to optimally matched with the negative electrode, achieving reliable efficiency matching without increasing the total amount of active materials and thus preserving high energy density.
3Reliability
If irreversible additive with low operation voltage (1.0 V to 2.5 V) is added to positive electrode, then irreversible efficiency is decreased and matched with negative electrode, but positive electrode operation voltage range is reduced
Solution Approach 1:
The patent applies preliminary action by designing the irreversible additive to operate only during initial charging at low voltage (1.0-2.5 V vs Li), where it consumes lithium to adjust irreversible efficiency. During normal charge-discharge cycles, the positive electrode operates at its full voltage range (3.7-4.2 V vs Li), and the additive remains inactive. This preliminary action during initial charging achieves irreversible efficiency matching without restricting the operational voltage range during actual battery use.
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 effectively adjusts the irreversible efficiency of the positive electrode, aligning it with the negative electrode, resulting in increased battery capacity and energy density by ensuring the additive only participates in the initial charge reaction.
Implementation Method 1
the irreversible additive participates in reaction only during initial charge and does not participate in reaction during discharge
Implementation Method 2
since the irreversible additive may exhibit high conductivity in some cases, a conductive network composition of the electrode may be improved
Data Source
AI summary
Disclosed is a positive electrode mix for secondary batteries including an irreversible additive. More particularly, provided is a positive electrode mix for secondary batteries including an irreversible additive that decreases irreversible efficiency of a positive electrode active material and a positive electrode.