Silicon-Dominant Li-Ion Cells With Controlled Anode Lithiation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithium-ion battery anodes, particularly those using graphite, face inefficiencies and limited cycle life due to mechanical degradation and unstable solid electrolyte interphase (SEI) formation caused by silicon's large volume changes during lithiation and delithiation, which affects energy density and safety.
Innovation Solution
A system and method for silicon-dominant lithium-ion cells with controlled lithiation of silicon, where the silicon anode is pre-lithiated to maintain a specific lithium level within upper and lower limits, minimizing volume changes and stabilizing the SEI, thereby enhancing cycle life and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as the dominant anode material to increase energy density, then the battery capacity and energy density are improved, but the large volume changes during lithiation and delithiation cause mechanical degradation and unstable SEI formation, reducing cycle life
Solution Approach 1:
The patent applies parameter changes by controlling the lithiation level of silicon within a specific range (0.05 ≤ x ≤ 2.0 in LiₓSi) and maintaining the silicon phase structure (avoiding complete amorphization). By adjusting these parameters, the invention achieves high energy density while preventing mechanical degradation and stabilizing SEI formation, thus resolving the contradiction between energy density and cycle life
Solution Approach 2:
The patent employs preliminary action through pre-lithiation of the silicon anode before battery assembly. This pre-lithiation process creates a stable initial state that prevents excessive volume expansion during subsequent cycling, thereby improving cycle life while maintaining high energy density capabilities
2Ease of manufacture
If conventional graphite anodes are used, then the battery structure is simple and manufacturing is easier, but the energy density is limited and charging speed is slower
Solution Approach 1:
The patent changes the anode material parameter from conventional graphite to silicon with controlled lithiation (specific phase structure and composition range). This parameter change enables faster lithium ion insertion/extraction kinetics, significantly improving charging speed while maintaining manufacturing feasibility through established battery assembly processes
3Quantity of substance
If silicon is fully lithiated to maximize capacity, then the energy density is maximized, but the volume expansion causes mechanical degradation and capacity fading
Solution Approach 1:
The patent optimizes the lithiation parameter to a specific range (0.05 ≤ x ≤ 2.0 in LiₓSi) rather than full lithiation, maintaining the silicon crystalline phase structure. This parameter optimization achieves high capacity (up to 3579 mAh/g theoretical) while preserving structural stability and preventing mechanical degradation, resolving the contradiction between capacity and structural 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
This approach improves the cycle life and energy density of lithium-ion batteries by controlling lithiation levels, reducing mechanical degradation, and maintaining a stable SEI, enabling faster charging and higher capacity utilization while minimizing cell expansion and capacity fading.
Implementation Method 1
silicon's large volume changes during lithiation and delithiation
Implementation Method 2
silicon's large volume changes during lithiation and delithiation
Implementation Method 3
unstable solid electrolyte interphase (SEI) formation caused by silicon's large volume changes
Data Source
AI summary
Systems and methods for silicon dominant lithium-ion cells with controlled lithiation of silicon may include a cathode, an electrolyte, and an anode. The anode may include silicon lithiated at a level after discharge that is configured to be above a minimum threshold level, where the minimum threshold lithiation is 3% silicon lithiation. The lithiation level of the silicon after charging the battery may range between 30% and 95% silicon lithiation, between 30% and 75% silicon lithiation, between 30% and 65% silicon lithiation, or between 30% and 50% silicon lithiation. The lithiation level of the silicon after discharging the battery may range between 3% and 50% silicon lithiation, between 3% and 30% silicon lithiation, or between 3% and 10% silicon lithiation. The minimum threshold level may be a lithiation level below which a cycle life of the battery degrades. The electrolyte may include a liquid, solid, or gel.