Lithium-Ion Battery Cathode Using Irreversible Capacity for Safety
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Solution Overview
Problem
Conventional lithium-ion batteries using lithium-free metal oxides as cathode active materials face safety issues due to the reactivity of lithium metal with water and electrolytes, leading to exothermic reactions and high reactivity at high temperatures.
Innovation Solution
A lithium-ion battery system utilizing a cathode active material composed of a mixture of lithium-free metal oxides, such as MnO2 and MoO3, combined with lithium-containing materials like Li2NiO2, which have high irreversible capacity, and using carbon as the anode instead of lithium metal to enhance safety and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium metal is used as an anode to provide Li source in batteries using Li-free metal oxide cathode, then the battery can achieve basic lithium ion transfer function, but safety problems occur due to high reactivity of Li metal with water and electrolyte causing exothermic reactions
Solution Approach 1:
The patent extracts the harmful lithium metal anode from the system and replaces it with a lithium-free anode material (such as carbon or lithium-free metal oxide). The lithium source is instead provided by the cathode material itself (Li-containing material with high irreversible capacity), thereby eliminating the safety hazards associated with lithium metal while maintaining the battery's lithium ion transfer function
Solution Approach 2:
The patent employs composite cathode materials consisting of Li-free metal oxide combined with Li-containing materials having high irreversible capacity (such as Li2NiO2, Li2CuO2). This composite structure enables the cathode to serve dual functions: providing the lithium source through irreversible capacity and facilitating reversible lithium ion transfer during charge-discharge cycles, thereby eliminating the need for separate lithium metal anode
2Device complexity
If Li-free metal oxide is used as cathode active material, then the battery structure can be simplified, but Li metal must be used as anode which creates safety issues and increases device complexity due to special handling requirements
Solution Approach 1:
The patent makes the cathode material multi-functional by designing it to simultaneously serve as both the lithium source (through high irreversible capacity) and the active material for reversible lithium ion transfer. This eliminates the need for a separate lithium metal anode, simplifying the battery structure while improving safety by removing the hazardous lithium metal component
3Quantity of substance
If Li metal is used as anode, then sufficient lithium source is provided, but high reactivity with electrolyte at high temperature occurs leading to safety problems
Solution Approach 1:
The patent converts the traditionally harmful high irreversible capacity (which was considered waste) into a beneficial feature. The Li-containing material's high irreversible capacity during first charge becomes the lithium source for subsequent reversible cycles, eliminating the need for lithium metal anode and its associated reactivity problems with electrolyte at high temperatures
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 battery system achieves excellent discharge capacity and improved safety by leveraging the high irreversible capacity of the cathode materials, allowing for increased lithium ion intercalation/deintercalation while replacing hazardous lithium metal with carbon anodes, resulting in higher discharge capacity and reduced safety risks.
Implementation Method 1
a cathode active material comprising a lithium-free metal oxide and a lithium-containing material with high irreversible capacity... a material capable of lithium ion intercalation/ deintercalation
Implementation Method 2
the material with high irreversible capacity can provide an excessive amount of lithium ions in an irreversible manner upon the first charge/discharge cycle
Data Source
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AI summary
Disclosed is a cathode active material comprising a lithium-free metal oxide and a material with high irreversible capacity. A novel lithium ion battery system using the cathode active material is also disclosed. The battery, comprising a cathode using a mixture of a Li-free metal oxide and a material with high irreversible capacity, and an anode comprising carbon instead of Li metal, shows excellent safety compared to a conventional battery using lithium metal as an anode. Additionally, the novel battery system has a higher charge/discharge capacity compared to a battery using a conventional cathode active material such as lithium cobalt oxide, lithium nickel oxide or lithium manganese oxide.