Lithium-Ion Anode Interstitial Reservoir for Fast Charging
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Solution Overview
Problem
Lithium metal batteries face safety and cycling stability issues due to dendrite formation and thermal runaway, limiting their commercialization for electric vehicles and portable devices, despite efforts to address these problems, existing solutions are complex, costly, or laborious, and often use flammable electrolytes.
Innovation Solution
A lithium-ion battery design featuring an anode with interstitial spaces containing lithium-capturing groups, such as redox forming species or ionic liquids, to delay lithium ion entry and prevent dendrite formation, using a binder-free electrode with an electrically conductive porous layer to enhance safety and charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as anode active material to achieve high energy density, then specific capacity is improved (3,861 mAh/g), but dendrite formation occurs leading to internal shorting and thermal runaway
Solution Approach 1:
A solid electrolyte interphase (SEI) layer is formed on the lithium metal anode surface through electrolyte decomposition. This SEI layer acts as an intermediary that prevents direct contact between lithium metal and liquid electrolyte, blocking dendrite propagation pathways while maintaining lithium ion conductivity, thus resolving the contradiction between high capacity and cycling stability
Solution Approach 2:
A thin protective coating layer (such as artificial SEI or solid electrolyte membrane) is applied on the lithium metal anode surface. This flexible thin film conformally covers the lithium surface, preventing dendrite penetration and structural degradation during cycling, thereby maintaining both high capacity utilization and long cycle life
2Ease of operation
If organic liquid solvents are used in electrolyte to enable lithium ion transport, then battery operation is achieved, but thermal runaway and explosion occur due to high volatility and flammability
Solution Approach 1:
The electrolyte composition is modified by changing the physical state parameter from liquid to solid. Solid electrolytes (such as solid polymer electrolytes or inorganic solid electrolytes) are used instead of flammable liquid organic solvents, maintaining lithium ion transport capability while eliminating volatility and flammability, thus preventing thermal runaway
Solution Approach 2:
A composite electrolyte system is designed combining solid electrolyte components with lithium salt. This composite material provides both ionic conductivity necessary for battery operation and inherent thermal stability, replacing flammable liquid electrolytes while enabling safe battery operation
3Productivity
If lithium ions are rapidly transferred from cathode to anode during fast charging, then charging speed is improved, but lithium ion plating on particle surfaces occurs leading to dendrite formation
Solution Approach 1:
The anode structure is pre-designed with three-dimensional lithium ion reception sites (such as porous structures or surface modifications) that prepare the anode to uniformly accommodate incoming lithium ions during fast charging. This preliminary structural preparation prevents surface plating and dendrite formation even at high charging rates
Solution Approach 2:
The anode architecture is transformed from two-dimensional planar structure to three-dimensional porous or hierarchical structure. This dimensional change increases the surface area and provides multiple pathways for lithium ion insertion, distributing the charging current uniformly and preventing localized plating that leads to dendrites during fast charging
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 enables rapid recharging with high specific energy and long cycle life while preventing internal short circuits and thermal runaway, using a safer, non-flammable electrolyte, thus overcoming the limitations of lithium metal batteries.
Implementation Method 1
the lithium ion reservoir comprises lithium-capturing groups dispersed in a fluid residing in these interstitial spaces and the lithium-capturing groups are selected from (a) redox forming species that reversibly form a redox pair with a lithium ion
Implementation Method 2
lithium ions were transferred from the lithium metal anode to the cathode through the electrolyte
Implementation Method 3
a porous separator disposed between the anode and the cathode
Data Source
AI summary
Provided is a lithium-ion battery containing an anode, a cathode, a porous separator, and an electrolyte, wherein the anode comprises particles of an anode active material that are packed together to form an anode active material layer having interstitial spaces to accommodate a lithium ion reservoir disposed therein and configured to receive lithium ions from the cathode and enable lithium ions to enter the particles in a time-delayed manner, wherein the reservoir comprises lithium-capturing groups selected from (a) redox forming species that reversibly form a redox pair with a lithium ion when the battery is charged; (b) electron-donating groups interspaced between non-electron-donating groups; (c) anions and cations wherein the anions are more mobile than the cations; (d) chemical reducing groups that partially reduce lithium ions from Li+1 to Li+δ, wherein 0<δ<1; (e) an ionic liquid; (f) borate salt or phosphate salt; or (g) a combination thereof.