Secondary Battery Crosslinked Separator Coating for Anode Adhesion
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Solution Overview
Problem
Lithium-ion batteries face issues with adhesive force between the anode and separator, leading to delamination due to silicon-containing anode active material volume expansion and cracks in the separator coating layer, which reduce battery efficiency and lifespan.
Innovation Solution
A secondary battery design featuring a binder polymer with a first repeating unit and a coating layer with a second repeating unit, derived from a crosslinking agent, forming a crosslinked matrix between the anode and the separator to enhance adhesive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-containing anode active material is used to achieve high capacity, then battery capacity is improved, but volume expansion of 300% or more occurs during charging causing structural collapse and delamination
Solution Approach 1:
The invention changes the physical and chemical parameters of the separator coating layer by introducing a crosslinking agent that reacts with the binder polymer to form a crosslinked structure. This crosslinked coating layer has different mechanical properties (higher elasticity and adhesion) compared to the original non-crosslinked layer, enabling it to accommodate the 300% volume expansion of silicon anode during charging while maintaining structural integrity and preventing delamination.
Solution Approach 2:
The invention creates a composite structure by combining the binder polymer with a crosslinking agent in the separator coating layer. This composite crosslinked structure integrates the advantages of both components: the binder polymer provides baseline adhesion while the crosslinked network adds elasticity and mechanical strength, enabling the coating to withstand the extreme volume changes of silicon anode without cracking or delaminating.
2Reliability
If conventional separator coating is used to provide insulation, then electrochemical stability is achieved, but adhesive force between anode and separator is insufficient leading to delamination
Solution Approach 1:
The invention modifies the chemical parameters of the separator coating by adding a crosslinking agent that forms covalent bonds with the binder polymer. This chemical transformation increases the adhesive strength parameter of the coating layer while preserving its electrochemical stability, as the crosslinked structure maintains the insulating properties necessary for safe battery operation.
Solution Approach 2:
The invention creates a composite coating layer that combines the insulating binder polymer with a crosslinking agent. This composite structure provides both electrochemical stability (from the polymer matrix) and enhanced adhesive force (from the crosslinked network), simultaneously satisfying both requirements that conventional single-material coatings cannot meet.
3Reliability
If separator coating layer is used to provide insulation, then electrochemical stability is improved, but cracks occur during discharging reducing battery efficiency
Solution Approach 1:
The invention changes the mechanical parameters of the separator coating by forming a crosslinked structure that exhibits enhanced elasticity and flexibility. This crosslinked coating can dynamically respond to volume changes during charging and discharging cycles, maintaining coating integrity and preventing cracks that would otherwise reduce battery efficiency while preserving electrochemical stability.
Solution Approach 2:
The crosslinked composite coating layer combines the electrochemical stability of the binder polymer with the crack-resistant properties of the crosslinked network. This composite structure maintains coating integrity during discharging when volume contraction occurs, preventing crack formation that would reduce battery efficiency while maintaining the insulating properties necessary for electrochemical stability.
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 crosslinked matrix significantly increases the adhesive force between the anode and the separator, preventing delamination and cracks, thus improving battery efficiency and extending lifespan by mitigating volume expansion and mechanical stress.
Implementation Method 1
the coating layer comprises a second repeating unit, and the first repeating unit and the second repeating unit are bonded to each other
Data Source
AI summary
Disclosed is a secondary battery that can increase the adhesive force between the anode and the separator on an electrolyte. The secondary battery includes an anode, a cathode, a separator which is between the anode and the cathode and includes a porous substrate and a coating layer on at least one surface of the porous substrate, and an electrolyte, The anode contains a binder polymer including a first repeating unit, the coating layer includes a second repeating unit, and the first repeating unit and the second repeating unit are bonded to each other.