Coated Over-Lithiated Cathodes to Suppress Battery Voltage Decay
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Solution Overview
Problem
Lithium secondary batteries using over-lithiated oxide particles experience voltage decay and deteriorated electrochemical performance due to high operation voltages.
Innovation Solution
Incorporating a coating material containing specific elements on the surface of over-lithiated oxide particles, with an upper operation voltage limit of 4.5 V or less, to suppress voltage decay and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If over-lithiated oxide particles are used as cathode active material to achieve high capacity, then the battery exhibits high reversible capacity (250 mAh/g or more), but voltage decay occurs and electrochemical performance deteriorates due to high operation voltages
Solution Approach 1:
A coating layer comprising at least one element selected from group 13 elements (Al, Ga, In), group 14 elements (Si, Ge, Sn, Pb), or group 15 elements (P, As, Sb, Bi) is formed on the surface of the over-lithiated oxide particles. This coating layer acts as an intermediary between the cathode active material and the electrolyte, suppressing voltage decay and improving electrochemical performance while maintaining high reversible capacity of 250 mAh/g or more
2Power
If the operation voltage is increased to activate Li2MnO3 domains for high capacity, then electrochemical activity is improved, but voltage decay accelerates and operational stability deteriorates
Solution Approach 1:
The coating layer changes the surface properties and electrochemical parameters of the over-lithiated oxide particles, enabling stable operation at high voltages (4.3 V or more vs. Li/Li+) required to activate Li2MnO3 domains. The coating prevents harmful side reactions at high potentials while maintaining the electrochemical activity needed for high capacity
3Use of energy by moving object
If over-lithiated oxide particles with Li2MnO3 domains are used to achieve capacity beyond 230 mAh/g, then energy density is improved, but voltage decay and performance deterioration occur
Solution Approach 1:
The cathode active material is designed as a composite structure where over-lithiated oxide particles containing Li2MnO3 domains (providing high capacity) are coated with a protective layer of specific elements. This composite approach combines the high energy density benefits of Li2MnO3 (achieving 250 mAh/g or more) with the stability provided by the coating, preventing voltage decay and performance deterioration
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 lithium secondary battery achieves high capacity and improved operational reliability by suppressing voltage decay and maintaining electrochemical performance.
Implementation Method 1
The over-lithiated oxide particles may exhibit a reversible capacity of 250 mAh/g or more by an electrochemical reaction of Li2MnO3
Implementation Method 2
A secondary battery is a battery which can be repeatedly charged and discharged, and has been widely applied to portable electronic devices such as a mobile phone, a laptop computer, etc. as a power source thereof
Implementation Method 3
The lithium secondary battery may store an electric energy by a difference in chemical potential when lithium ions are intercalated and deintercalated between a cathode and an anode
Implementation Method 4
a coating material formed on at least a portion of the surface of the over-lithiated oxide particles and containing a coating element
Data Source
AI summary
A lithium secondary battery according to exemplary embodiments may include a cathode which includes: a cathode current collector, and a cathode active material layer formed on the cathode current collector and including cathode active material particles; and an anode disposed to face the cathode. The cathode active material particles may include activated over-lithiated oxide particles and a coating material formed on at least a portion of the surface of the activated particles and containing a coating element. An upper limit of operation voltage of the lithium secondary battery may be 4.5 V or less relative to the oxidation-reduction potential of lithium.