Silane Electrolyte Additives for High-Voltage Li-Ion Battery Stability
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Solution Overview
Problem
Lithium ion batteries face poor high-temperature storage performance and cycle life due to oxidative decomposition of the electrolyte on the positive electrode, especially under high voltage conditions, which existing additives and electrolytes fail to adequately address.
Innovation Solution
An electrolyte containing a compound with cyclic unsaturated double bonds and silicon, which forms a polymerized interface film at the electrode/electrolyte interface, reducing surface activity and oxidative decomposition, and enhancing thermal stability and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional electrolyte is used under high voltage (4.4V) and high temperature conditions, then the battery can operate at high voltage, but the electrolyte is easily oxidized and decomposed on the positive electrode surface, causing deterioration of positive electrode material
Solution Approach 1:
The patent introduces a silane-based additive as an intermediary substance that mediates between the electrolyte and the positive electrode. This additive preferentially reacts with the electrode surface to form a protective interface film, acting as a mediator that prevents direct contact and harmful oxidation reactions between the conventional electrolyte and the high-voltage electrode material.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding specific silane compounds (containing Si-O-Si structures) to change the interfacial chemical environment. This parameter change enables the formation of a stable protective film that alters the electrochemical window and reduces oxidation potential at the interface, allowing high-voltage operation without electrolyte decomposition.
2Reliability
If existing additives like tetravinylsilane (TVS) are used to improve high temperature performance, then cycle performance improves, but DCR (direct current resistance) growth increases, making it difficult to promote in the market
Solution Approach 1:
The patent changes the chemical structure parameters of the silane additive by introducing specific cyclic structures and controlling the Si-O-Si bond configuration. This structural parameter change enables the formation of a thinner, more stable interface film with lower resistance characteristics, thereby reducing DCR growth while maintaining high temperature cycle performance.
Solution Approach 2:
The patent creates a composite interface structure consisting of the silane-based protective film combined with the underlying electrode material. This composite structure provides both protection against high-temperature degradation and maintains good electrical conductivity, achieving a balance between reliability and low resistance.
3Reliability
If existing additives like thiophene are used to improve cycle performance, then cycle performance improves, but storage performance deteriorates with poor stability and large self-discharge
Solution Approach 1:
The patent changes the chemical composition parameters by replacing sulfur-containing heterocyclic structures (like thiophene) with silicon-oxygen-based structures. This parameter change fundamentally alters the chemical stability characteristics, eliminating the self-discharge and storage instability issues while preserving the cycle performance enhancement through protective film formation.
4Reliability
If coating or doping technology is applied to improve high-temperature storage performance, then some performance improvement is achieved, but the technology is far from perfect and match problems with electrolytes remain
Solution Approach 1:
The silane additive serves as a chemical intermediary that simplifies the protection mechanism. Instead of complex physical coating or doping processes, the additive automatically forms a protective interface film through electrochemical reactions, providing a simpler and more compatible solution that works seamlessly with conventional electrolytes.
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 significantly improves high-temperature storage and cycle performance by forming a stable interface film that inhibits oxidative decomposition and protects the positive electrode, leading to better thermal stability and capacity retention.
Implementation Method 1
cyclic unsaturated double bonds containing silicon of the additive is polymerized at the electrode/electrolyte interface to form a thinner interface film
Implementation Method 2
reducing the surface activity of the positive electrode and inhibiting the oxidative decomposition of the electrolyte
Data Source
AI summary
An additive adapted for an electrolyte of a lithium ion battery, includes a compound represented by Formula I or Formula II: wherein R1-R6, R9 and R12 are each independently selected from hydrogen atom, halogen atom, silane, a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C1-C12 alkenyl group, and a substituted or unsubstituted C6-C26 aryl group; R7-R8 and R10-R11 are each independently selected from silane, a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C1-C12 alkenyl group, and a substituted or unsubstituted C6-C26 aryl group. The additive can reduce the surface activity of the positive electrode and inhibit the oxidative decomposition of the electrolyte, thereby improving the high temperature storage performance and high temperature cycle performance of the ternary lithium ion battery under a high voltage of 4.4V.