Active Material Coating for Battery Degradation
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Solution Overview
Problem
Lithium-ion accumulators face capacity and performance losses due to electrode degradation, including chemical reactions that form a Solid Electrolyte Interphase (SEI) and structural changes in cathode materials, leading to mechanical stresses and fragmentation, which current coatings cannot adequately prevent while maintaining conductivity.
Innovation Solution
An active material body with a multifunctional coating system where each layer has a modulus of elasticity progressively lower than the previous, ensuring mechanical integrity and conductivity, applied using precise methods like chemical vapor deposition to maintain a thin, conformal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dense coating is applied to the surface of the active material to protect against unwanted reactions with the electrolyte, then protection against degradation is improved, but electrical resistance increases and lithium ion conductivity decreases
Solution Approach 1:
The coating is applied as an ultra-thin layer (1-5 nm) only where needed on the particle surface, providing localized protection against electrolyte degradation while minimizing the barrier effect on lithium ion diffusion and electron transport. This local application resolves the contradiction by providing sufficient protection without the excessive thickness that would cause high resistance.
Solution Approach 2:
The invention changes the thickness parameter of the coating to an ultra-thin range (1-5 nm), which fundamentally alters the coating's properties from being a significant barrier to being a minimal obstacle for ion and electron transport while still providing adequate protection against unwanted reactions.
2Reliability
If the coating thickness is increased to improve protection, then degradation resistance is improved, but lithium ion conductivity and charging capacity are limited
Solution Approach 1:
The coating is applied as an ultra-thin layer (1-5 nm) only where needed on the particle surface, providing localized protection against electrolyte degradation while minimizing the barrier effect on lithium ion diffusion and electron transport. This local application resolves the contradiction by providing sufficient protection without the excessive thickness that would cause high resistance.
Solution Approach 2:
The invention changes the thickness parameter of the coating to an ultra-thin range (1-5 nm), which fundamentally alters the coating's properties from being a significant barrier to being a minimal obstacle for ion and electron transport while still providing adequate protection against unwanted reactions.
3Reliability
If current coating processes are used to provide protection, then some degradation resistance is achieved, but the coating uniformity and thinness cannot be guaranteed
Solution Approach 1:
The invention replaces conventional mechanical or wet chemical coating processes with atomic layer deposition (ALD), a vapor-phase process that deposits material atom-by-atom in self-limiting cycles. This substitution enables precise control of coating thickness and uniformity at the nanometer and sub-nanometer scale, resolving the contradiction between providing adequate protection and achieving uniform thin coatings.
Solution Approach 2:
The invention uses vapor-phase deposition processes (atomic layer deposition) where coating material is delivered through controlled gas flow. This pneumatic delivery system enables precise control of coating thickness and uniformity by controlling the number of deposition cycles and gas flow parameters, resolving the manufacturing precision issue.
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 coating system effectively prevents fragmentation and maintains mechanical integrity by buffering volume changes and ensuring lithium ion conductivity, reducing stress and internal resistance, thus enhancing the lifespan and performance of lithium-ion accumulators for rapid charging.
Implementation Method 1
The coating system effectively prevents fragmentation and maintains mechanical integrity by buffering volume changes and ensuring lithium ion conductivity
Implementation Method 2
applied using precise methods like chemical vapor deposition to maintain a thin, conformal layer
Implementation Method 3
ensuring lithium ion conductivity
Data Source
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AI summary
Active material body (1) for an accumulator (2), wherein the active material body (1) comprises at least one active material (3) having an active material elastic modulus EA, and at least one layered first coating (5) arranged on a surface (4) of the active material (3), wherein the first coating (5) consists of a first material (6) having a first elastic modulus E1; wherein: first elastic modulus ≤ active material elastic modulus.