FIELD OF THE INVENTION

This invention relates to new titanium disulfide-sulfur (TiS2—S) composites, as well as to cathodes and batteries (e.g., Li—S batteries) comprising the composites, and related methods and processes. The composites are conducive toward use in an improved cathode, e.g., for an Li—S battery.

BACKGROUND

The demand for high-energy density batteries is increasing rapidly as there is a need for reliable and cost-effective energy storage in both mobile and stationary electrical energy-storage technologies. Metal sulfur batteries are one of the most promising platforms for meeting these needs because of the high theoretical specific capacity of the sulfur cathode (1675 mAhg), which is about eight times the typical value for the most promising intercalating cathodes (e.g. 200 mAhG for LiNi0.8Co0.15Al0.05O2(NCA)) in use within today's lithium-ion batteries (LIBs). In particular, lithium-sulfur (Li—S) batteries are a promising technology because of their high theoretical energy density and low cost. When paired with a lithium metal anode, which also boasts more than a 10-fold improvement in theoretical specific capacity (3800 mAhG) relative to the graphitic carbon anode (372 mAhG) generally used in LIBs, the sulfur cathode becomes legitimately one of the most important conversion cathodes, because it enables a battery technology with exceptional specific energy per unit mass (2600 Whkg) or per unit volume (2800 WhL). However, problems relative to Li—S batteries remain, including those relating to cycle life and efficiency.

Thus, a need exists for improved Li—S batteries and compositions that are conducive to improved cell performance.

While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.

In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was, at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.

SUMMARY OF THE INVENTION

Briefly, the present invention satisfies the need for, inter alfa, new composites that are conducive toward use in an improved Li—S battery.

The invention provides new titanium disulfide-sulfur (TiS2—S) composites, as well as cathodes and batteries (e.g., Li—S batteries) comprising the composites, and related methods and processes. As described herein, Applicants have discovered a TiS2material that is a promising sulfur host for Li—S batteries. Embodiments of cathodes comprising embodiments of the inventive titanium disulfide-sulfur (TiS2—S) composites demonstrate favorable electrochemical performance, including improved capacity, improved capacity retention and/or improved coulombic efficiency.

Embodiments of the invention may address one or more of the problems and deficiencies discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.

Certain embodiments of the presently-disclosed TiS2—S composites and related methods and articles/devices have several features, no single one of which is solely responsible for their desirable attributes. Without limiting the scope of the TiS2—S composites and related methods and articles/devices as defined by the claims that follow, their more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section of this specification entitled “Detailed Description of the Invention,” one will understand how the features of the various embodiments disclosed herein provide a number of advantages over the current state of the art. These advantages may include, without limitation, providing TiS2—S composite embodiments having enhanced electrochemical properties, which, when employed in a cathode (e.g., for a Li—S battery) provide exceptional capacity retention.

In a first aspect, the invention provides a titanium disulfide-sulfur (TiS2—S) composite particle comprising a titanium disulfide (TiS2) substrate having solid elemental sulfur (S) disposed directly on a surface of the TiS2, wherein the TiS2substrate has a layered crystalline hexagonal structure of space group P-3 ml and comprises at least 100 distinct layers, and wherein the TiS2and S are present in the composite in a weight ratio (TiS2:S) of 20:80 to 50:50.

In a second aspect, the invention provides a cathode comprising the TiS2—S composite particle according to the first aspect of the invention.

In a third aspect, the invention provides a lithium-sulfur (Li—S) battery comprising: an anode; a cathode according to the second aspect of the invention; and a separator, wherein the separator is positioned between the anode and the cathode.

In a fourth aspect, the invention provides a process for manufacturing the cathode according to the second aspect of the invention, comprising mixing TiS2—S composite particles, carbon black, and binder in solvent to form a slurry, applying the slurry to a current collector, and drying the slurry to form the coating.

These and other objects, features, and advantages of this invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings.

