United States Patent and Trademark Office >
As the world transitions to a green future, more and more electrified applications are turning to battery storage systems. To meet wide-ranging consumer needs manufacturers are developing lithium-ion batteries (LIBs) with higher energy densities, enhanced safety, and faster charging to suit applications from consumer electronics and grid energy storage to electric vehicles (EVs).
Key to enabling these advances are the battery electrodes. As a result, considering the abundance, environmental friendliness, low cost, and high capacity potential of a silicon-based anode, silicon has emerged as one of the most promising anode materials for high-energy and fast-charging LIBs.
However, even though using silicon as an active anode material provides many advantages, including greater energy density and faster charging, it is reactive and requires careful processing in a non-oxidizing environment.
StoreDot’s patent relates to innovative methods of preparing anode active material for fast-charging lithium-ion batteries, comprising silicon particles coated with silver and /or tin particles, and mixing the coated silicon particles with conductive additives and binders in a solvent to form an anode slurry used to prepare the anode.
United States Patent and Trademark Office: Methods of preparing silver and/or tin coated silicon active material and anode slurries formed therefrom >
Silicon (Si) is one of the most studied anode materials because of its low cost, low electrochemical potential vs. Li/Li+, and theoretical capacity of more than 10 times that of graphite. However, amongst other challenges, Si anodes suffer from reactivity that requires careful processing in a non-oxidizing environment and low electric conductivity.
To improve the conductivity and overall electrochemical performance of Si-dominant anodes composite coatings with tin and silver metal nanoparticles can be used.
Thus, StoreDot’s patent describes methods of preparing Si-based anode slurries and an anode made thereof. The innovation consists of coating silicon particles, ranging in size between 300-700 nm, with silver and /or tin particles of 20-500 nm. Thereafter the coated silicon particles are mixed with conductive additives and binders in a solvent to form an anode slurry, used to prepare a less reactive anode.
Alternatively or complementarily, silicon particles may be milled in an organic solvent, with the possibility of adding coating agent(s), conductive additive(s), and binder(s) to the milled silicon particles to form a Si-based anode slurry. Alternatively or complementarily, milled silicon particles may be mixed, in a first organic solvent, with coating agent(s), conductive additive(s), and binder (s) to form the Si-based anode slurry.
Furthermore, the innovation also enables the mixture of silicon particles with nanoparticles (NPs) and a carbon-based binder and/or surfactant. These NPs comprise one or more metalloid oxide NPs, metalloid salt NPs, Sb and/or Cu salt NPs, Sn, Sb, Cu, SnSb alloy and/or SnCu alloy NPs, metallic Ag, Au, Pb and/or Ge NPs, and carbon NPs. The mixture is reduced to yield coated silicon particles with a passivation coating, that when consolidated forms the anode.
These innovative methods disclosed in StoreDot’s patent simplify the anode production process whilst delivering anodes with equivalent or superior performance.