Gru Energy Lab Inc.

The Trustees of Boston College

Sa Zhou

Song Han

Xiaohua Liu

Dunwei Wang

Xiahui Yao

Xinghua Meng

Provided are methods of forming active materials for electrochemical cells using low-temperature electrochemical deposition, e.g., at less than 200° C. Specifically, these processes allow precise control of the morphology, composition, and/or size of the deposited structures. For example, a deposited structure may be doped, alloyed, or surface treated during its formation using a combination of different precursors. In particular, a silicon structure may be prelithiated while being formed. Different working electrodes (e.g., with different surface sizes and properties) allow forming different types of structures, e.g., precipitating particles from the solution or specific types of films deposited on the working electrode. These processes require minimal energy and do not use volatile precursors. Furthermore, these processes produce a more confined waste stream, suitable for post-reaction recycling. Finally, low-temperature electrochemical deposition can be readily scaled up.

Methods of forming active materials for electrochemical cells using low-temperature electrochemical deposition

Provided are methods of forming active materials for electrochemical cells using low-temperature electrochemical deposition, e.g., less than 200&#xb0; C. Specifically, these processes allow precise control of the morphology, composition, and size of deposited structures. For example, the deposited structure may be doped, alloyed, or surface treated during their deposition using a combination of different precursors. In particular, silicon structure may be pre-lithiated while these structures are being formed. The selection of working electrodes (surface size and properties), electrolyte composition, and other parameters result in different types of structures, e.g., precipitating from the electrolyte or deposited on the electrode. Low-temperature plating does not require a lot of energy and volatile and invisible precursors. Furthermore, this plating produces a more confined waste stream, suitable for post-reaction recycling. Finally, low-temperature electrochemical deposition can be readily scaled up such that plating bathes and electrode sizes can be chosen to fit the production requirements.

Provided are new solid-state electrochemical cells and methods for fabricating these cells. In some examples, a solid-state electrochemical cell is assembled using a negative electrode, a positive electrode, and a gel-polymer electrolyte layer, which is disposed and provides ionic communications between these electrodes. Prior to this assembly, the negative electrode is free from electrolytes. The negative electrode is fabricated using a coating technique, e.g., forming a slurry, comprising a polymer binder and one or more negative active materials structures, such as silicon, graphite, and the like. The porosity, size, and other characteristics of the negative active materials structures and of the resulting coated later are specifically controlled to ensure operation with the gel-polymer electrolyte layer or, more specifically, high-rate charge and discharge, e.g., greater than 1 mA/cm. The gel-polymer electrolyte layer releases some of its liquid electrolyte after the interface with the negative electrode is formed.

Solid-state electrochemical cells comprising coated negative electrodes and methods of fabricating thereof

Provided are methods for solid state pretreatment of active materials (e.g., prelithiation of silicon monoxide) while forming treated negative active material structures. Also provided are the formed structures, negative electrodes comprising these structures, and electrochemical cells comprising these electrodes. In some examples, silicon monoxide structures are mixed with lithium hydroxide structures or some other lithium-containing structures. The mixture is heated in an inert environment to form treated negative active material structures. These treated structures comprise various lithium-containing components, some of which trap lithium. When an electrochemical cell, formed with these treated negative active material structures, is initially charged and additional new lithium ions are introduced into the negative electrodes (e.g., from the positive electrode), a larger portion of these new lithium ions forms reversible components (rather than irreversible components) in the negative electrode than, for example, in a conventional cell without any such treatment.

Solid state pretreatment of active materials for negative electrodes in electrochemical cells

Provided are electrodes for use in electrochemical cells and active material components used to form these electrodes. Also provided are methods of forming these active material components as well as methods of forming these electrodes. An electrode comprises a current collector and an active layer, comprising active material structures and an inorganic conductive layer. The inorganic conductive layer coats and binds together these active material structures. Furthermore, the inorganic conductive layer also provides adhesion of the active layer to the current collector. The inorganic conductive layer has an electronic conductivity of at least 10S/m and provides an electronic path among the active material structures and, in some examples, between the active material structures and the current collector. In some embodiments, the same inorganic conductive layer shared by multiple active material structures.

Inorganic conductive layers for electrochemical cells

Provided are hybrid active material structures for use in electrodes of electrochemical cells and methods of forming these structures. A hybrid active material structure comprises at least one first substructure and at least one second substructures, each comprising a different layered active material and interfacing each other. Combining multiple layered active materials into the same structure and arranging these materials in specific ways allow achieving synergetic effects of their desirable characteristics. For example, a layered active material, which forms a stable solid electrolyte interface (SEI) layer, may be form an outer shell of a hybrid active material structure and interface with electrolyte. This shell may surround another layered active material, which has a higher capacity but would otherwise forma a less stable SEI layer. Furthermore, multiple layered active materials may be arranged into a stack, in which one of these materials may operate as an ionic and/or electronic conductor.

Hybrid active material structures for electrochemical cells

Provided are methods of introducing additional lithium ions into lithium-ion electrochemical cells as well as positive electrodes, comprising these additional lithium ions. A method may involve introducing a temporary lithium additive into a positive electrode, such as mixing the additive into slurry used for coating the electrode. The positive electrode also comprises a positive active material, different from the temporary lithium additive and used as a source of primary lithium ions. The positive active material is operable to release and also later to receive lithium ions during cycling. The temporary lithium additive is operable to release additional lithium ions during its decomposition, but not to receive any lithium ions thereafter. The amount of these additional lithium ions may be selected based on expected lithium ion losses in the cell. The temporary lithium additive may decompose when applying a voltage between the electrodes, e.g., during initial cycling.

Positive electrodes with active materials and temporary lithium additives for lithium ion electrochemical cells

The invention generally relates to new materials based on C49 titanium disilicide (TiSi) as a new, layered anode material, within which lithium ions can react with the Si-only layers. Stabilization by a coating a thin layer of oxide on the surface of TiSisignificantly improves the charge and discharge performance.

Layered titanium disilicide, method of preparation and applications thereof

The embodiments disclosed herein relate to the fabrication of complex two-dimensional conductive silicide nanostructures, and methods of fabricating the nanostructures. In an embodiment, a conductive silicide includes a plurality of connected and spaced-apart nanobeams linked together at an about 90-degree angle, the plurality of nanobeams forming a two-dimensional nanostructure having a mesh-like appearance. In an embodiment, a method of fabricating a two-dimensional conductive silicide includes performing chemical vapor deposition, wherein one or more gas or liquid precursor materials carried by a carrier gas stream react to form a nanostructure having a mesh-like appearance and including a plurality of connected and spaced-apart nanobeams linked together at an about 90-degree angle.

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San Jose, CA, United States of America

Sa Zhou