Semi-Solid Pre-Formed Electrodes for Li-Ion Batteries
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Solution Overview
Problem
Conventional lithium ion batteries have electrodes less than 100 μM thick, resulting in lower capacity, energy density, and higher inactive-to-active material ratios, along with undesirable film formation during the formation process, which increases manufacturing time and expense.
Innovation Solution
The development of semi-solid electrodes thicker than 100 μM, with distinct SEI layers on the anode and cathode, formed independently to avoid surface film deposition, using a method that involves loading active materials into molds, pressing, and injecting electrolytes with specific additives to create pre-formed electrodes for lithium ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional thin electrodes (less than 100 μM) are used, then the manufacturing process is simpler, but the battery capacity and energy density are reduced
Solution Approach 1:
The patent changes the physical state parameter of the electrode from solid to semi-solid, enabling thickness greater than 100 μM while maintaining manufacturing feasibility. This parameter change resolves the contradiction by allowing thicker electrodes (increasing capacity and energy density) without proportionally increasing manufacturing complexity
Solution Approach 2:
The electrode undergoes preliminary formation processing independently before battery assembly, creating stable SEI layers in advance. This preliminary action prevents undesirable film formation during subsequent battery formation, thereby simplifying the overall manufacturing process while enabling use of thicker, higher-capacity electrodes
2Reliability
If both anode and cathode electrolyte additives are used in the electrolyte, then the electrolyte composition is more complete, but undesirable films are formed on the electrodes during formation
Solution Approach 1:
The electrode is pre-formed with stable SEI layers using specific electrolyte additives before battery assembly. This preliminary formation eliminates the need for formation cycles after assembly, preventing undesirable film formation while maintaining complete electrolyte composition
Solution Approach 2:
Different electrolyte additives are used for anode and cathode during their respective preliminary formation processes, creating electrode-specific SEI layers. This local quality approach ensures each electrode develops optimal protective films without interfering with the other, preventing harmful cross-reactions
3Reliability
If multiple charge and discharge cycles are performed for formation, then SEI layer formation is enhanced, but the manufacturing time and expense increase
Solution Approach 1:
The electrode undergoes complete formation processing before battery assembly, performing the function of multiple charge-discharge cycles in advance. This preliminary action creates stable SEI layers that prevent subsequent formation cycles from being needed, thereby reducing manufacturing time and expense while maintaining SEI layer quality
Solution Approach 2:
The formation process is segmented into independent electrode-level preliminary formation and final battery assembly. This segmentation allows formation to occur under optimized conditions for each electrode type, achieving better SEI layers faster, and eliminates the need for repeated formation cycles
4Stability of the object's composition
If binders are used in conventional electrode preparation, then the electrode structure is more stable, but the ionic conductivity is reduced due to increased tortuosity
Solution Approach 1:
The patent changes the physical state from solid to semi-solid, eliminating the need for traditional binders. This parameter change maintains electrode structure stability through the semi-solid matrix while removing the tortuosity introduced by binder materials, thereby improving ionic conductivity
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 results in batteries with higher capacity, energy density, and conductivity, reducing the ratio of inactive to active materials and simplifying the manufacturing process, while avoiding undesirable film formation and enhancing cycle life and rate capability.
Implementation Method 1
A solid electrolyte interface (SEI) is formed on the anode and/or the cathode, based on the electrolyte design, during the formation process. SEI layers passivate the electrode-electrolyte interfaces and prevent side reactions during battery usage.
Implementation Method 2
The electrodes are densely packed and pressed to high densities
Data Source
AI summary
This disclosure relates to semi-solid electrodes which are pre-formed prior to inclusion in lithium ion batteries, lithium ion batteries which incorporate the semi-solid electrodes and methods of making the semi-solid electrodes. An electrochemical cell includes a semi-solid anode formed of anode active material injected with an electrolyte and a first electrolyte additive, the semi-solid anode having a first SEI layer; and a semi-solid cathode formed of a cathode active material injected with an additional electrolyte and a second electrolyte additive, the semi-solid cathode having a second SEI layer, wherein the first electrolyte additive and the second solid electrolyte additive are different.