Composition-Gradient Electrodes for Thick Battery Capacity Limits
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Solution Overview
Problem
Conventional battery electrodes face limitations in thickness due to reduced conductivity and manufacturing challenges, leading to reduced energy density and performance, as thicker electrodes experience diffusion limitations and are difficult to manufacture without compromising rate capability and charge capacity.
Innovation Solution
The development of high energy density electrodes with a compositional gradient, featuring a first electrode material with a specific porosity and a second electrode material with varying porosity, including a mixture of active and conductive materials in a liquid electrolyte, allowing for increased thickness without reducing ionic conductivity, and incorporating high-capacity materials like silicon and tin alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrode thickness is increased to increase total ion/electron storage capacity, then energy density is improved, but conductivity is reduced leading to reduced charge capacity
Solution Approach 1:
The electrode employs a composition gradient where the active material concentration varies through the thickness of the electrode. The first portion (closer to electrolyte) has a first concentration of active material, while the second portion (closer to collector) has a second concentration that differs from the first. This local variation in composition optimizes both ion storage capacity in the high-concentration region and electrical conductivity in the adjacent region, resolving the contradiction between capacity and conductivity.
2Quantity of substance
If high-capacity materials are used to increase theoretical energy density, then energy density is improved, but volumetric expansion and contraction occurs causing damage
Solution Approach 1:
The electrode structure places high-capacity active materials in the first portion closer to the electrolyte where ion storage is prioritized, while the second portion closer to the collector has a different composition that provides structural stability. This spatial differentiation allows the high-capacity materials to contribute to energy density without causing excessive volumetric expansion that would compromise overall electrode integrity.
Solution Approach 2:
The electrode uses a composite structure with varying composition through its thickness, combining high-capacity materials with other materials in different proportions at different locations. This composite approach enables the electrode to achieve high theoretical energy density from the high-capacity materials while the composite nature provides structural resilience against volumetric expansion and contraction during cycling.
3Quantity of substance
If electrode thickness is increased to reduce inactive components ratio, then energy density is improved, but manufacturing difficulty increases
Solution Approach 1:
The electrode employs a composition gradient where the active material concentration parameter varies continuously or in steps through the thickness of the electrode. This parameter change approach allows the electrode to achieve high active material content and energy density while maintaining a structure that can be manufactured using conventional techniques, as the gradient can be achieved through controlled deposition or processing methods rather than requiring complex assembly of multiple discrete layers.
Data Source
AI summary
Embodiments described herein relate generally to devices, systems and methods of producing high energy density electrodes including a first electrode material disposed on a current collector and having a first porosity, and a second electrode material disposed on the first electrode material and having a second porosity less than the first porosity. In some embodiments, the second electrode material includes a mixture of an active material and a conductive material in a liquid electrolyte. In some embodiments, the first electrode materials can have a different composition than the second electrode material. In some embodiments, the first electrode material can include a high-capacity material such as tin, silicon antimony, aluminum, or titanium oxide. In some embodiments, a lithium-containing material can be disposed between the first electrode material and the second electrode material.