FIELD

The present technology is generally related to electroactive materials and batteries containing such electroactive materials exhibiting superior cycle stability, less volume expansion, and high specific capacity, and methods to prepare the electroactive materials and batteries containing the same.

BACKGROUND

Since the first commercialization by Sony Corporation in the early 1990s, lithium-ion batteries have become the main power source for the portable electronics markets and are now showing great potential use for in the automobile market. However, due to the limited abundance of lithium, it is not enough to meet the increasing demands for large-scale applications, e.g. grid scale stationary energy storage. Moreover, the lithium resources are non-uniformly distributed in the world (about 40% are in South America) and are mainly monopolized by four companies, which will lead to sustained price increases in the near future. Sodium-ion batteries are considered as a potential alternative to lithium ion batteries due to the greater abundance and lower cost of sodium. Moreover, both lithium and sodium are alkali metals and they share similar physical and chemical properties.

With regard to cathodes for sodium ion batteries, layered NaNi1/3Co1/3Mn1/3O2, spinel NaMn2O4, olivine NaFePO4, NaFeSO4F, and their analogues have been already been reported and were found to have similar electrochemical behaviors relative to their lithium-based cathode material counterparts in terms of specific capacity, cycle life and rate capability, with the exception of lower working voltage.

Anodes for sodium ion batteries, however, have other challenges due to the larger ionic radius of Na+(1.02 Å) compared to Li+(0.67 Å). Graphite, the anode material of choice in state-of-the-art lithium ion batteries, can only store a small amount of sodium due to the insufficient interlayer distances and stretched C—C bonds induced by sodiation. This leads to thermodynamic instability in Na-graphite intercalation compounds. Meanwhile, silicon, has been shown to be a promising high energy density anode for the next generation lithium ion batteries. Unfortunately, it is of limited use in sodium ion batteries due to the high diffusion barrier for Na ions in Si lattices. Hard carbon, the most deployed anode materials for industrial application, has a reversible capacity of less than 300 mAh/g. Moreover, the low working voltage (close to 0 V vs. Na/Na+) may trigger sodium dendrite growth, posing severe safety risks, particularly under high temperature and high rate cycling conditions.

SUMMARY

In one aspect, a [PxSbyMz]p/[carbon]qcomposite is provided wherein x, y, and z represent atomic percentage values and are x>0; y>0; and z≥0; M is an electrically conductive metal; and p and q represent the weight percentage values of the composite wherein p and q are in the range of 0-100%. In some embodiments, p and q represent the weight percentage values of the composite with p+q=100 wt % and where is p>0 and 0≤q<100. In some embodiments, M includes at least one of tin, germanium, silicon, lead, arsenic, selenium, bismuth, aluminum, nickel, manganese, molybdenum, niobium, tungsten, tantalum, iron, copper, titanium, vanadium, chromium, nickel, cobalt, zirconium, or yttrium.

In another aspect, an anode active material is provided that include the [PxSbyMz]p/[carbon]qcomposite.

In another aspect, an electrochemical device is provided including a cathode that includes a cathode active material, and an anode that includes any of the anode active materials described herein. The electrochemical device may be a sodium ion battery, according to various embodiments.

In another aspect, a method of preparing a [PxSbyMz]p/[carbon]qcomposite is provided, where the method includes ball milling a mixture of P, Sb, M, and a conductive carbon a ratio to form the [PxSbyMz]p/[carbon]qcomposite; and recovering the [PxSbyMz]p/[carbon]qcomposite; wherein x, y, and z represent atomic percentage values and are x>0; y>0; and z≥0; M is an electrically conductive metal; and p and q represent the weight percentage values of the composite wherein p and q are in the range of 0-100%. In some embodiments, p and q represent the weight percentage values of the composite with p+q=100 wt % and where is p>0 and 0≤q<100.

