Pre-Sodiated Anode Assembly for High-ICE Energy Storage Cells
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Solution Overview
Problem
Existing energy storage devices, such as lithium-ion batteries, suffer from low initial coulombic efficiency (ICE) due to irreversible loss of lithium ions during the formation of the solid-electrolyte interface (SEI), which reduces their energy density and cycle life.
Innovation Solution
The method involves manufacturing energy storage devices using a pre-sodiated anode with a solid electrolyte interface (SEI) layer, combined with a lithium ion-containing cathode and electrolyte, allowing for increased initial coulombic efficiency and reduced lithium ion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional anode is used in a lithium-ion battery, then the device can be manufactured with standard processes, but the initial coulombic efficiency is low due to irreversible loss of lithium ions during SEI formation
Solution Approach 1:
The patent applies preliminary action by pre-sodiating the anode before final assembly. The anode is pre-treated with sodium ions to form a stable SEI layer in advance, so that when the battery is assembled with lithium ion-containing electrolyte, the SEI is already formed and prevents subsequent lithium ion consumption. This preliminary preparation eliminates the irreversible lithium ion loss that would normally occur during first charge.
Solution Approach 2:
The patent uses sodium ions as an intermediary substance. Instead of directly using lithium ions to form the SEI (which causes irreversible loss), sodium ions are used as a mediator to form the SEI layer first. The sodium ions fulfill the function of SEI formation without being the final charge carriers, thereby protecting the lithium ions from irreversible consumption while still enabling high initial coulombic efficiency.
2Quantity of substance
If lithium ions are used for pre-doping the anode, then the anode potential is lowered and energy density is increased, but the cost increases due to expensive lithium material
Solution Approach 1:
The patent replaces expensive lithium material with cheaper sodium material for the pre-doping function. Sodium is abundant and much less expensive than lithium, while still achieving the desired effect of lowering anode potential and forming a stable SEI layer. The sodium serves as a disposable intermediary that fulfills its function during manufacturing without needing to be the permanent charge carrier.
Solution Approach 2:
The patent changes the chemical parameter of the pre-doping element from lithium to sodium. This substitution maintains the functional effect of lowering anode potential and forming SEI, while dramatically reducing material cost due to sodium's abundance and lower price. The parameter change from Li to Na achieves the same technical function at a fraction of the cost.
3Reliability
If a large amount of lithium ions are consumed during SEI formation in the first cycle, then the SEI layer is formed, but the remaining capacity of the cell is reduced
Solution Approach 1:
Sodium ions serve as an intermediary that forms the SEI layer without being the final charge carrier. The sodium ions are consumed during SEI formation (fulfilling the necessary function), but since they are not the primary charge carriers, their consumption does not reduce the cell's remaining capacity for subsequent cycles. The lithium ions are preserved for their intended function of charge storage.
Solution Approach 2:
The patent uses sodium ions as a disposable material specifically for SEI formation. These sodium ions are intentionally consumed during the pre-doping stage to create the protective SEI layer, but since they are replaced by lithium ions for subsequent charge-discharge cycles, their consumption does not impact the cell's long-term capacity. The expensive lithium ions are protected from this irreversible consumption.
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 significantly enhances the initial coulombic efficiency, leading to improved energy density and extended cycle life of the energy storage devices, while also reducing production costs and environmental impact by using sodium instead of lithium.
Implementation Method 1
During charging, the metal ions will be extracted from the cathode and diffuse through the electrolyte to intercalate or alloy in the anode
Implementation Method 2
irreversible loss of lithium ions during the formation of the solid-electrolyte interface (SEI)
Implementation Method 3
an electrolyte to allow diffusion of charge carrier ions
Implementation Method 4
a separator to prevent the electrodes from contacting each other while still allowing diffusion of ions
Implementation Method 5
metal ions and anions from the electrolyte will adsorb onto the surface of each electrode upon charging
Data Source
AI summary
A method is for manufacturing an energy storage device, wherein the method includes the steps of providing a pre-sodiated anode having a solid electrolyte interface layer and assembling the energy storage device by combining the pre-sodiated anode together with a lithium ion-containing cathode and a lithium ion-containing electrolyte. The invention further relates to an energy storage device having a cathode including lithium ions, a separator, and a lithium salt-containing electrolyte in a suitable case, wherein the energy storage device further has a pre-sodiated anode.