Cyclic Siloxane Electrolyte for Stable Silicon Battery Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon-based anodes and nickel-rich cathodes in lithium-ion batteries face structural instability due to anisotropic volume changes and interface deterioration, leading to electrolyte decomposition and depletion, which hinders their practical application.
Innovation Solution
Incorporating cyclic siloxane and/or its ring-opening polymerization derivatives into the electrolyte, positive electrode active material, or negative electrode active material, where one group with stronger electron withdrawing properties than phenyl is directly linked to silicon, forming a silicone rubber-like structure to stabilize the electrode/electrolyte interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based anodes are used to achieve high energy density, then battery capacity is improved, but interface stability deteriorates due to extreme volume change (about 300%) during lithiation/delithiation
Solution Approach 1:
The cyclic siloxane performs preliminary action by proactively forming a stable interface layer on the silicon anode surface before significant volume changes occur. This pre-formed protective layer prevents subsequent electrolyte decomposition and interface deterioration that would normally result from the 300% volume expansion during lithiation.
Solution Approach 2:
The cyclic siloxane acts as an intermediary substance between the silicon anode and the electrolyte. It forms a mediating interface layer that absorbs and accommodates the volume changes of silicon, preventing direct contact and interaction between the electrolyte and silicon surface, thereby stabilizing the interface while allowing high capacity operation.
2Stability of the object's composition
If conventional electrolyte additives are used to generate interface components, then some interface protection is achieved, but interface structure fracture and excessive electrolyte consumption still occur due to huge volume effect
Solution Approach 1:
The invention changes the chemical parameters of the electrolyte additive by selecting cyclic siloxane with specific molecular structure and properties. This parameter change enables the formation of a more robust interface layer that can withstand the mechanical stress of silicon volume expansion, preventing interface fracture and reducing electrolyte consumption compared to conventional additives.
3Stability of the object's composition
If interface modification is performed to adapt to volume effect, then interface stability is improved, but interface structure fracture still occurs due to anisotropic volume changes
Solution Approach 1:
The cyclic siloxane forms a flexible interface film on the silicon anode surface. This flexible film can dynamically accommodate and adapt to the anisotropic volume changes of silicon during lithiation/delithiation, maintaining interface stability and preventing structure fracture through its mechanical flexibility rather than rigid protection.
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 solution enhances interface stability, preventing interface structure fracture and excessive electrolyte decomposition, thereby maintaining battery performance over a long period despite significant volume changes.
Implementation Method 1
ring-opening polymerization derivatives thereof
Data Source
AI summary
A secondary battery contains cyclic siloxane and/or ring-opening polymerization derivative thereof, where a cyclic structure of the cyclic siloxane has at least onestructure, one and only one of R1 and R2 contains a group with stronger electron withdrawing property than phenyl, and the group is directly linked to Si.