Lithium-Ion Battery Separator with Lithium-Releasing Composite Particles
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Solution Overview
Problem
Lithium ion secondary batteries face significant irreversible capacity loss due to the initial irreversible reaction of negative electrode materials like Sn and Si, which affects their energy density and practical application.
Innovation Solution
A lithium ion secondary battery design featuring a separator with composite particles having a core of lithium composite metal oxide coated with carbon, which facilitates lithium deintercalation during the initial charge to supplement the irreversible capacity loss, and a porous film with a lithium-providing layer and a heat-resistant layer to manage voltage and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic materials like Si and Sn are used as negative electrode active materials to achieve high energy density, then theoretical capacity increases to about 4 times of carbonaceous material, but irreversible capacity loss occurs due to formation of Li2O during initial charge
Solution Approach 1:
The separator is pre-loaded with lithium composite metal oxide particles that can release lithium ions during initial charge. This preliminary action anticipates the lithium consumption by SnO negative electrode, providing a reserve lithium source before the irreversible reaction occurs, thereby compensating for the capacity loss without requiring excess lithium in the negative electrode
Solution Approach 2:
The separator acts as an intermediary between the positive and negative electrodes, incorporating lithium composite metal oxide particles that can transfer lithium ions to the negative electrode during initial charge. This mediator function allows the separator to actively compensate for lithium consumption, transforming the separator from a passive component to an active lithium source
2Reliability
If a porous coating layer with inorganic particles is formed on the separator surface to improve battery performance, then manufacturing complexity increases, but the separator structure becomes more complex
Solution Approach 1:
The separator employs a composite structure combining porous substrate with a coating layer containing inorganic particles (such as Al2O3, SiO2, TiO2) dispersed in a binder. This composite material approach enhances the separator's functional properties including lithium ion conductivity, thermal stability, and mechanical strength, while the particles are distributed throughout the coating layer to provide multiple benefits simultaneously
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 effectively reduces irreversible capacity loss and maintains higher capacity retention by providing lithium ions during the initial charge, enhancing the battery's overall performance and energy density.
Implementation Method 1
the composite particles (A) cause lithium deintercalation at 0.1 V-2.5 V (vs. Li+/Li) during the initial charge of the battery to supplement an irreversible capacity of the negative electrode
Implementation Method 2
a shell portion comprising a carbonaceous material with which a surface of the core is coated at least partially
Data Source
Figure 1~2
Figure 3~4
AI summary
The present disclosure relates to a separator for a lithium ion secondary battery and a battery comprising the separator. The separator supplements the irreversible capacity of a negative electrode. The separator comprises composite particles (A), and the composite particles (A) include a core portion comprising lithium composite metal oxide particles and a shell portion comprising a carbonaceous material with which the core surface is coated at least partially; the composite particles (A) cause lithium deintercalation at 0.1 V to 2.5 V (vs. Li+/Li); the battery has a positive electrode potential of 3 V or more (vs. Li+/Li); and the battery has a driving voltage of 2.5 V to 4.5 V.