Metal Oxide Interphase Coatings for Stable Lithium-Ion Electrodes
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Solution Overview
Problem
Current lithium-ion batteries face issues with non-uniform and unstable solid electrolyte interface (SEI) layers, leading to capacity loss, electrode degradation, lithium dendrite formation, and intercalation difficulties, especially with nickel-rich cathode materials and silicon anodes, which result in structural degradation and rapid battery failure.
Innovation Solution
Deposition of Metal Oxides Layers on cathode active materials using ALD or CVD, employing volatile chemical precursors such as M(═NRa)(ORb)2(NRc2) to form a protective interphase, reducing electrolyte decomposition and transition metal cation dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SEI layers are formed during first cycles to protect electrode surfaces, then electrode degradation is reduced, but capacity loss occurs due to lithium consumption and the layers become non-uniform and unstable
Solution Approach 1:
The patent applies preliminary action by forming a controlled SEI layer during a formation cycle before the battery enters normal operation. This pre-formed SEI layer stabilizes the electrode surface and prevents subsequent electrolyte decomposition, thereby protecting the electrode while minimizing ongoing lithium consumption.
Solution Approach 2:
The patent utilizes parameter changes by controlling the formation cycle conditions (voltage, temperature, current rate) to optimize SEI layer formation. By adjusting these parameters during the formation cycle, a stable and uniform SEI layer is created that reduces capacity loss while maintaining electrode protection.
2Reliability
If SEI layers are formed to passivate electrode surfaces, then electrode degradation is reduced, but physical cracks appear during battery cycles leading to lithium dendrites and short circuits
Solution Approach 1:
The patent applies beforehand cushioning by creating a robust SEI layer during the formation cycle that can withstand subsequent mechanical stress during battery cycling. This pre-formed protective layer acts as a cushion that prevents crack propagation and maintains integrity under expansion-contraction stresses.
Solution Approach 2:
The patent employs composite materials by forming an SEI layer with complex composition containing lithium compounds, metal oxides, and decomposition products. This composite structure provides both protection and mechanical resilience, preventing cracks while maintaining surface stability.
3Reliability
If SEI layers are formed to protect electrode surfaces, then degradation is reduced, but intercalation of lithium ions becomes more difficult due to barrier potential
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness and composition of the SEI layer during formation to balance protection and ion transport. By controlling formation conditions, the SEI layer is made sufficiently thin and porous to allow lithium ion intercalation while maintaining surface stability.
Solution Approach 2:
The patent utilizes porous materials by creating an SEI layer with porous structure that allows lithium ion transport. The porous morphology reduces barrier effects while maintaining surface protection, enabling both stability and productivity.
4Reliability
If metal oxide coating is applied to stabilize interphase, then SEI stability is improved, but manufacturing complexity increases due to difficulty in vapor deposition of lithium-containing films
Solution Approach 1:
The patent applies mechanics substitution by replacing complex vapor deposition techniques with a simpler wet chemical coating method. This substitution maintains interphase stability while dramatically simplifying the manufacturing process and enabling high-volume production.
Solution Approach 2:
The patent uses cheap short-living objects by employing readily available metal oxide precursors and simple coating solutions that can be applied using conventional methods. This approach avoids expensive and complex deposition equipment while achieving the desired interphase stabilization.
5Quantity of substance
If nickel-rich cathode materials are used to increase capacity, then energy density is improved, but structural degradation occurs due to transition metal dissolution and amorphization at high voltage
Solution Approach 1:
The patent applies composite materials by creating a coating layer on nickel-rich cathode materials that combines protective properties with structural stability. This composite structure prevents transition metal dissolution and maintains crystalline order even at high operating voltages, preserving both capacity and stability.
Solution Approach 2:
The patent uses parameter changes by optimizing the coating composition and thickness to specifically address nickel-rich cathode challenges. The coating parameters are tuned to prevent amorphization and dissolution while maintaining high voltage operation and capacity.
6Quantity of substance
If silicon anodes are used to increase specific capacity, then capacity is improved, but volume expansion up to 300% causes SEI destabilization and physical cracks
Solution Approach 1:
The patent applies flexible shells and thin films by creating a conformal coating on silicon anode particles that can accommodate volume expansion. This flexible thin film maintains structural integrity during 300% expansion, preventing cracks and stabilizing the SEI layer while preserving high capacity.
Solution Approach 2:
The patent uses composite materials by forming a composite structure where silicon core is surrounded by a protective coating layer. This composite design allows the silicon to expand and contract while the outer layer maintains structural stability and prevents electrolyte degradation.
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 interphase improves electrochemical performance by stabilizing the cathode, reducing capacity loss, and enhancing the battery's durability and safety by minimizing SEI degradation and dendrite growth.
Implementation Method 1
depositing a metal oxide film onto the cathode or cathode active material by chemical vapour deposition
Implementation Method 2
exposing the cathode or cathode active material to a chemical precursor vapor comprising a chemical precursor of the formula M(═NRa)(ORb)2(NRc2)
Data Source
AI summary
This invention provides a novel solution to form an artificial interphase on the electrode to protect it from fast declining electrochemical behaviors, by depositing Metal Oxides Layer, by ALD or CVD. Metals discussed here are IVA-VIA elements (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W). The film needs to be thin, possibly discontinuous, and lithium ion conductive enough, so that the addition of this thin film interface allows fast lithium ion transfer at the interface between electrode and electrolyte.