Lithium Battery Chemistry — Part 1

Si-based anodes can achive 10 times the gravimetric capacity than the standard graphite electrode and thus represent a promising path for improving the energy density of current Li-ion batteries. Although the mechanical instabilities and substantial volumetric fluctuations inherent to silicon (Si) anodes have been largely mitigated over the last decade, the calendar life of these materials remains a primary obstacle to the commercial viability of pure or Si-rich anodes. This presentation elucidates the fundamental relationships between the solid electrolyte interphase (SEI) and the operational efficacy of the Si anode, focusing on the influence of film composition, morphology, and topology.

Interfacial reactions in Li-ion cells almost always generate gases. By measuring the quantity and type of gases we can understand these reactions. In our efforts to develop high energy density Li-ion cells, we screen novel electrolyte additives with Online Electrochemical Mass Spectrometry (OEMS). This is an operando gas analysis method that continuously samples the evolved/consumed gases in battery cells. At Dalhousie we built a novel multi-channel OEMS system that can sample gases from up to six battery cells with a single quadrupole mass analyzer. We will explain how this system helps us to understand the reaction mechanisms of new additives.

Over a decade ago, our team pioneered chemical vapor deposition (CVD)-enabled nanostructured silicon/carbon (Si/C) composite anodes (US Patents with 2009-2013 priorities: US 8,889,295B2; US 2014/0057179 A1; US20230343939A1) and created scalable synthesis tool architectures for their high-volume commercial production. This technological breakthrough is now widely recognized, with nearly all global battery, device, transportation, robotics, and technology companies incorporating CVD-produced Si/C into their roadmaps for all major Li-ion cell formats (cylindrical, coin, pouch, prismatic) and cathode chemistries. Tens of millions of electronic devices, over a million of power tools, drones and two-wheelers and over hundred thousand of EVs now comprise Si/C anodes.

We will present 100 mA/cm2 current densities and 99.995% Li-cycling Coulombic efficiency using our novel 3D anode architecture and recently developed mixed ionic and electronic conducting garnet. By reducing dense layer thickness and incorporating higher energy density cathodes we will further show ≥500 Wh/kg full cell performance. All at room temperature with zero applied pressure

The chemical and structural stability of sulfur cathodes in rechargeable lithium-sulfur batteries has been a persistent challenge. We have been focused on the development of sulfurized polyacrylonitrile (SPAN) as an alternative to elemental sulfur. In this talk, we will discuss the fundamental principles in composition and microstructure behind its stability as well as applying these principles to design composite sulfur/sulfide materials that offer higher capacities.

We have recently developed a unique solid-state composite polymer electrolyte capable of operating efficiently with lithium metal, opening new pathways for high-energy-density batteries. Proof-of-concept studies and detailed characterization have been performed in lithium–air, lithium–sulfur, and lithium-ion battery cells, demonstrating its versatility across multiple chemistries. Since its initial development, our efforts have focused on optimizing the electrolyte’s physicochemical properties to enable scalable manufacturing. In this presentation, I will highlight our latest findings and discuss the opportunities and challenges of implementing this electrolyte in advanced lithium-metal and lithium-ion battery technologies, with a primary focus on Li–air systems.

Silicon-rich lithium-ion batteries offer high energy density but face significant calendar-life challenges for automotive applications . While substantial progress has been made in improving cycle life, long-term degradation during storage remains insufficiently understood and underreported. This talk highlights the key mechanisms driving calendar aging in silicon-based cells and reviews emerging mitigation strategies. It also presents an integrated characterization framework to accelerate optimization and enhance calendar-life performance.

To enable long electric drive range for electric vehicles (EVs), there is a need to develop battery systems that offer at least 300 Wh/kg energy density or higher. In this talk, we will discuss several strategies to increase significantly the energy density and improve the safety of lithium battery through the development of a) nickel rich and low cobalt cathode, b) high voltage nonflammable electrolyte, and c) novel high-capacity Si/graphene anode. To further increase the energy and lower the cost, we will describe a novel doped Sulfur system with a novel electrolyte that suppresses the dissolution of polysulfide species.

Cathode in lithium-ion batteries is the most expensive, limits operating voltage and energy density, and contributes to safety. Chemical bonding, specifically the degree of covalence in metal-oxygen bond, plays a critical role on cell performance parameters, yet its role is largely obscured or ignored. This presentation will illustrate with examples how chemical bonding impacts the various battery performance parameters. The understanding will also be extended to emerging sodium-ion battery chemistry. How do changes in chemical bonding alter battery performance parameters? How can the battery performance parameters be tuned by modulating chemical bonding? What determines the degree of covalence in chemical bonds?