Lithium Secondary Battery Cathode Structure for Rate and Lifetime
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Solution Overview
Problem
Conventional lithium secondary batteries using overlithiated lithium manganese-based oxides face issues with low electrochemical properties and stability due to excessive lithium and manganese, leading to transition metal dissolution and degradation of rate capability and lifetime.
Innovation Solution
A lithium secondary battery design that incorporates a positive electrode active material with a lithium manganese-based oxide formed as a core-shell particle, where a concentration gradient of transition metals is established from the core to the shell, and a barrier layer is applied to inhibit transition metal dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If overlithiated lithium manganese-based oxide is used as positive electrode active material, then theoretical high capacity under high voltage operating environment is achieved, but electric conductivity becomes low and rate characteristic deteriorates
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of transition metals within the lithium manganese-based oxide particle. The core region has a different composition than the shell region, with the shell having optimized transition metal content to improve electric conductivity and rate characteristics while the core maintains high lithium content for capacity. This spatial differentiation of composition allows simultaneous optimization of capacity and rate performance.
Solution Approach 2:
The patent uses composite materials by combining lithium manganese-based oxide with a barrier layer coating. The composite structure integrates the high-capacity lithium manganese-based oxide core with a protective shell that improves electric conductivity and prevents transition metal dissolution, thereby achieving both high capacity and good rate characteristics.
2Power
If overlithiated lithium manganese-based oxide is used, then high voltage operating environment capability is achieved, but transition metal dissolution increases and lifetime deteriorates
Solution Approach 1:
The patent introduces a barrier layer as an intermediary between the lithium manganese-based oxide and the electrolyte. This barrier layer mediates the interaction by preventing direct contact between the transition metals and the electrolyte, thereby inhibiting dissolution while allowing the battery to operate at high voltages. The barrier layer acts as a protective interface that maintains structural integrity over time.
Solution Approach 2:
The patent converts the harmful effect of excess transition metals (which cause dissolution and degradation) into a beneficial structure by organizing them in a controlled concentration gradient within the core-shell particle. The shell region with optimized transition metal content actually protects the core region, and the overall structure benefits from the presence of transition metals while minimizing their harmful dissolution effects.
3Quantity of substance
If excess lithium and manganese are included in lithium manganese-based oxide, then theoretical high capacity is achieved, but electrochemical properties and stability become poor
Solution Approach 1:
The patent applies local quality by creating distinct regions within the particle with different compositions. The core region contains excess lithium and manganese for high capacity, while the shell region has optimized composition for electrochemical stability. This spatial separation allows each region to fulfill its specific function without compromising the other.
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 proposed solution effectively prevents the degradation of rate capability and extends the lifetime of lithium secondary batteries by reducing transition metal dissolution and enhancing electrochemical properties to commercial levels.
Implementation Method 1
a barrier layer is applied to inhibit transition metal dissolution
Implementation Method 2
lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Data Source
AI summary
The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery which has an improved capacity and lifetime maintenance rate by controlling a voltage range during formation or operation of the lithium secondary battery. In addition, the present invention relates to a lithium secondary battery in which the degradation of the electrochemical properties of a lithium secondary battery, including rate capability, caused by an excess of lithium and manganese in the lithium manganese-based oxide used as a positive electrode active material, is prevented, and particularly, the lifetime deterioration is prevented by inhibiting or mitigating the dissolution of a transition metal from the lithium manganese-based oxide.