Silicon Anode Microstructure in Non-Aqueous Proton Batteries
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Solution Overview
Problem
Rechargeable lithium metal batteries face challenges due to lithium dendrite formation and silicon anode degradation, leading to reduced cycle life and capacity in proton conducting batteries, especially with the use of aqueous electrolytes which are corrosive to silicon-based materials.
Innovation Solution
Proton conducting batteries with non-aqueous electrolytes and silicon-based anodes having a polycrystalline, nanocrystalline, or amorphous microstructure, utilizing group 14 elements like silicon and germanium, and incorporating non-group 14 elements at specific atomic percentages, along with aprotic compounds and acid additives, to achieve high discharge capacities above 800 mAh/g.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as an anode material in lithium ion batteries, then theoretical specific capacity is very high (4000 mAh/g), but volumetric lattice expansion occurs when cycling with lithium
Solution Approach 1:
The patent changes the chemical environment parameter from lithium-based to proton-based electrolyte, which fundamentally alters how silicon interacts with the electrolyte. This parameter change prevents the harmful lithium-silicon alloying reactions that cause expansion, while still allowing proton insertion to achieve high capacity without the same structural degradation
Solution Approach 2:
The patent introduces a non-aqueous proton-conducting electrolyte as an intermediary medium between the silicon anode and cathode. This intermediary enables proton transport while preventing direct contact between silicon and water, eliminating corrosion issues and allowing the silicon to maintain structural integrity during cycling
2Quantity of substance
If film thickness of silicon anode is increased above 250 nanometers, then capacity increases, but critical fracture stress, reduced capacity, and poor cycle life occur
Solution Approach 1:
The patent changes the electrolyte composition parameter from aqueous to non-aqueous proton-conducting, which fundamentally alters the mechanical and chemical environment. This parameter change allows thicker silicon films to be used without fracture because the non-aqueous electrolyte does not cause the same corrosion and swelling issues that lead to critical fracture stress in traditional systems
3Reliability
If aqueous electrolyte is used in proton conducting batteries, then proton conduction is enabled, but corrosive damage occurs to silicon based materials
Solution Approach 1:
The patent introduces a non-aqueous proton-conducting electrolyte as an intermediary that enables proton transport without containing water. This intermediary substance provides the necessary proton conduction pathway while eliminating the corrosive effects of water on silicon-based anode materials, solving both requirements simultaneously
Solution Approach 2:
The patent creates an inert chemical environment using non-aqueous electrolyte that does not react with or corrode the silicon anode. This inert environment maintains silicon structural integrity while still allowing electrochemical reactions to proceed through proton insertion and extraction
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 solution enables proton conducting batteries to achieve excellent capacity and cycle life, exceeding theoretical maximums, without the limitations of thin film anodes and aqueous electrolyte corrosion, thereby improving safety and cost profiles compared to lithium ion batteries.
Implementation Method 1
a non-aqueous electrolyte in between the anode and the cathode; wherein a discharge capacity of the rechargeable battery is above 800 mAh/g of the anode electrochemically active material
Implementation Method 2
silicon that is commonly used as an anode material in lithium ion batteries due to very high theoretical specific capacity (4000 mAh/g), undergoes a dramatic volumetric lattice expansion when cycling with lithium. This expansion of as much as 400% further reduces cycle life
Implementation Method 3
It is known that some materials such as metal hydride alloys and nickel hydroxide are capable of absorbing and desorbing hydrogen. When paired with an appropriate anode material, these hydrogen storage materials can be employed in fuel cells and metal hydride batteries.
Data Source
AI summary
Provided are proton conducing rechargeable batteries that display excellent capacity. The rechargeable batteries include a cathode comprising a cathode electrochemically active material capable of storing and releasing hydrogen, optionally including Ni, and an anode, the anode including an anode electrochemically active material of one or more group 14 elements, the anode electrochemically active material in the powder form and associated by a binder, wherein a microstructure of the anode electrochemically active material is polycrystalline, a mixture of nanocrystalline and amorphous, or a combination of polycrystalline, nanocrystalline and amorphous. The cells include a non-aqueous electrolyte and are a characterized by a discharge capacity above 800 mAh/g of the anode electrochemically active material above 1 Volt.