DE112020000025T5 - IMMOBILIZED SELENIUM IN A POROUS CARBON WITH THE PRESENCE OF OXYGEN AND USES IN A RECHARGEABLE BATTERY - Google Patents

Abstract

A selenium-carbon-oxygen mixture is formed in a manufacturing process for a system or a mass of immobilized selenium. The mixture is then heated to a temperature above the melting temperature of the selenium, and the heated mixture is then cooled to ambient or room temperature, thereby forming the system or mass of immobilized selenium.

Description

CROSS REFERENCE TO RELATED APPLICATION

This registration is a partial continuation of U.S. Patent Application No. 15/434 655 , filed February 16, 2017, and also claims U.S. Provisional Patent Application No. 62/802 929 , filed February 8, 2019. The disclosures of the above applications are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Field of invention

The present application relates to the field of high energy density lithium secondary batteries. In particular, the application relates to a method for producing carbon-selenium nanocomposite materials and their applications. The present invention also relates to immobilized selenium comprising selenium and carbon. It also relates to a method for producing and using the immobilized selenium. One of the uses of the immobilized selenium is in a rechargeable battery. The present invention also relates to a rechargeable battery capable of high-rate discharge-charge cycling (e.g. 10C rate) with a minimum level of capacity fading while being able to substantially maintain its electrochemical performance such as specific capacity recover when charged at a low rate such as a 0.1C rate.

Description of the prior art

In view of the increasing human demand for energy, secondary batteries with high mass specific energy and high volumetric energy density such as lithium-sulfur batteries and lithium-selenium batteries have attracted widespread interest. Group 6A elements of the periodic table, such as sulfur and selenium, have demonstrated two-electron reaction mechanisms in the electrochemical reaction process with lithium. Although the theoretical mass specific capacity of selenium (675 mAh / g) is lower than that of sulfur (1675 mAh / g), selenium has a higher density (4.82 g / cm ³ ) than sulfur (2.07 g / cm ^{3 3} ). Therefore, the theoretical volumetric energy density of selenium (3253 mAh / cm ³ ) is close to the theoretical volumetric energy density of sulfur (3467 mAh / cm ³ ). At the same time, compared to sulfur, which is close to an electrically insulating material, selenium is electrically semiconducting and shows better electrical conductivity properties. Compared to sulfur, selenium can therefore exhibit a higher level of activity and better usage efficiency even at a higher charge level, resulting in battery systems with high energy and power density. In addition, a selenium-carbon composite material can have a further improvement in the electrical conductivity compared to sulfur-carbon composite material in order to obtain an electrode material with a higher activity.

As disclosed in Patent Publication No. CN104393304A described, when hydrogen-selenium gas is allowed to pass through a graphene dispersion solution, the solvent heat reduces the graphene oxide in graphene, while it oxidizes the hydrogen-selenium in selenium. The selenium-graphene electrode material prepared in this way is paired with an ether electrolyte system, 1.5M lithium-bi-trifluoromethane-sulfonimide (LiTFSI) / 1,3-dioxolane (DOL) + dimethyl ether (DME) (volume ratio 1: 1); the specific charging capacity reaches 640 mAh / g (and approaches the theoretical specific capacity of selenium) in the first cycle. During the charge-discharge process, however, polyselenium ions dissolve in the electrolyte and show significant amounts of pendulum effect, which causes the subsequent decline in capacity. At the same time, the procedures for producing the graphene oxide raw material used in this process are complicated and not suitable for industrial production.

The patent CN104201389B discloses a lithium selenium battery cathode material employing a current collector with nitrogenous layered porous carbon composite material mixed with selenium. In preparing the current collector with nitrogen-containing layered porous carbon composite material, nitrogen-containing conductive polymer is first deposited or grown on the surface of a piece of paper, followed by alkali activation and high-temperature carbonization, which is achieved in a current collector with nitrogen-containing layered porous carbon composite material with carbon fiber as a network structure self carries, results; and such a nitrogen-containing layered porous carbon composite material current collector is then further mixed with selenium. The deposition method for making a conductive polymer is complicated, and the process of Film formation or growth is difficult to control. The preparation process is complicated, which goes hand in hand with undesirably high costs.

In addition, the demand for a long life, high energy density, high power density rechargeable battery with the ability to be charged and discharged at a rapid rate is increasing in electronics, electric / hybrid vehicle, air / space / drone, U -Boat and other industrial, military, and consumer applications are constantly increasing. Lithium-ion batteries are examples of rechargeable batteries in the above mentioned applications. However, the need for better performance and cycling ability has not been met with lithium-ion batteries as lithium-ion battery technology has matured.

Atomic oxygen has an atomic mass of 16 and an ability for 2 electron transfers. A rechargeable lithium-oxygen battery was tested for the purpose of making batteries with high energy density. When a battery involves an oxygen cathode paired with lithium or sodium metal as an anode, it will have the greatest stoichiometric energy density. Most of the technical problems with the Li // Na oxygen battery remain unsolved.

Elemental sulfur is also in the oxygen group and has the second highest energy density (after oxygen) when paired with a lithium or sodium metal anode. A lithium-sulfur or a sodium-sulfur battery has been extensively studied. Polysulfide ions (intermediates) that form during the discharge process of the Li-S or Na-S battery, however, dissolve in the electrolyte and oscillate from the cathode to the anode. Upon reaching the anode, polysulfide anions react with lithium or sodium metal, resulting in a loss of energy density, which is undesirable for a battery system. Additionally, sulfur is an insulator that requires a high level of charge of carbon materials to achieve a minimum level of electrical conductivity. Because of the extremely low conductivity of sulfur, Bein's Li / Na-S battery is very difficult to discharge or charge at a rapid rate.

SUMMARY OF THE INVENTION

A process for making a two-dimensional carbon nanomaterial that has a high degree of graphitization is disclosed herein. The two-dimensional carbon nanomaterials are mixed with selenium to obtain a carbon-selenium composite material, which is used as a cathode material, which is paired with an anode material containing lithium, resulting in a lithium-selenium battery having high Has energy density and stable electrochemical performance. A similar process can be used to further assemble a pouch cell that also exhibits excellent electrochemical properties.

A method for producing selenium-carbon composite material with readily available raw materials and simple preparation procedures is also disclosed.

The selenium-carbon composite material described herein can be obtained by a manufacturing method comprising the following steps:

(1) Organic alkali metal salts or organic alkaline earth metal salts are carbonized at high temperatures and then washed with dilute hydrochloric acid or other acids and dried to obtain a two-dimensional carbon material;

(2) The two-dimensional carbon material obtained in step (1) is mixed with selenium in organic solution, heated, and the organic solvent is evaporated, and then the mixing of selenium with the two-dimensional carbon material is carried out by a multi-stage heat ramp and Soaking procedure completed to obtain carbon-selenium composite material.

In step (1), the organic alkali metal salt can be selected from one or more of potassium citrate, potassium gluconate and sucrose acid sodium. The organic alkaline earth metal salt can be selected from either or both of calcium gluconate and sucrose acid calcium. The high temperature carbonization can be carried out at 600 to 1000 ° C, desirably 700 to 900 ° C; Carbonization time 1 to 10 hours, desirably 3 to 5 hours.

In step (2), the organic solvent can be selected from one or more of ethanol, dimethyl sulfoxide (DMSO), toluene, acetonitrile, N, N-dimethylformamide (DMF), carbon tetrachloride and Diethyl ether or ethyl acetate; the multi-stage heat ramp and soak section can be called a ramp rate of 2 to 10 ° C / min., desirably 5-8 ° C / min., followed by a temperature between 200 and 300 ° C, desirably between 220 and 280 ° C from soaking at the temperature for 3 to 10 hours, desirably 3 to 4 hours; then continue heating to 400 to 600 ° C, desirably 430 to 460 ° C, followed by soaking for 10 to 30 hours, desirably 15 to 20 hours.

A lithium-selenium secondary battery comprising the carbon-selenium composite materials is also disclosed herein. The lithium selenium secondary battery may further include: an anode containing lithium, a separator, and an electrolyte.

The lithium-containing anode can be one or more of lithium metal, lithiated graphite anode, and lithiated silicon-carbon anode materials (by assembling the graphite and silicon-carbon anode materials and lithium anode into a half-cell battery, discharging the lithiated graphite anode and to prepare lithiated silicon-carbon anode materials). The separator (membrane) can be a commercially available membrane such as, without limitation, a Celgard membrane, a Whatman membrane, a cellulose membrane, or a polymer membrane. The electrolyte can be one or more of a carbonate electrolyte, an ether electrolyte, and ionic liquids.

The carbonate electrolyte can be selected from one or more of diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and propylene carbonate (PC); and the solute can be selected from one or more of lithium hexafluorophosphate (LiPF ₆ ), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium perchlorate (LiC10 ₄ ) and lithium bis (fluorosulfonyl) imide (LiFSI ).

For the electrolytic ether solution, the solvent can be selected from one or more of 1,3-dioxolane (DOL), ethylene glycol dimethyl ether (DME), and triethylene glycol dimethyl ether (TEGDME); and the solute can be selected from one or more of lithium hexafluorophosphate (LiPF ₆ ), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium perchlorate (LiC10 ₄ ), and lithium bis-fluorosulfonylimide (LiFSI).

For ionic liquids, the ionic liquid can be one or more of ionic liquid at room temperature [EMIm] NTf2 (1-ethyl-3-methylimidazolium-bis-trifluoromethane-sulfonimide salt), [Pyl3] NTf2 (N-propyl-N-methylpyrrolidine- bistrifluoromethane sulfonimide salt), [PP13] NTf2 (N-propyl-methylpiperidine-alkoxy-N-bistrifluoromethane sulfonimide salt); and the solute can be selected from one or more of lithium hexafluorophosphate (LiPF ₆ ), bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium perchlorate (LiC10 ₄ ), and lithium bis-fluorosulfonylimide (LiFSI).

This also describes a lithium-selenium pouch cell battery which comprises the carbon-selenium composite material.

Compared with the prior art, referring to the method for producing selenium-carbon composite material disclosed herein, the two-dimensional carbon material has advantages that the raw materials are easily available at low cost, the production method is simple, high is practical and suitable for mass production, and the obtained selenium-carbon composite material exhibits excellent electrochemical properties.

Also disclosed herein is immobilized selenium (an immobilized selenium mass) comprising selenium and a carbon skeleton. The immobilized selenium comprises at least one of the following aspects: (a) It requires the recovery of sufficient energy for a selenium particle to have a kinetic energy of ≥ 9.5 kJ / mol, ≥ 9.7 kJ / mol, ≥ 9.9 kJ / mol, ≥ 10.1 kJ / mol, ≥ 10.3 kJ / mol or ≥ 10.5 kJ / mol reached in order to escape the immobilized selenium system; (b) a temperature of 490 ° C or higher, ≥ 500 ° C, ≥ 510 ° C, ≥ 520 ° C, ≥ 530 ° C, ≥ 540 ° C, ≥ 550 ° C or ≥ 560 ° C is required for this Selenium particles gain enough energy to escape the immobilized selenium system; (c) the carbon skeleton has a surface (with pores less than 20 angstroms) of ≥ 500 m ² / g, ≥ 600 m ² / g, ≥ 700 m ² / g, ≥ 800 m ² / g, ≥ 900 m ² / g or ≥ 1,000 m ² / g; (d) the carbon skeleton has a surface area (for pores between 20 angstroms and 1000 angstroms) of 20% or less, 15% or less, 10% or less, 5% or less, 3% or less, 2% or less, 1 % or less of the total surface.

A cathode or a rechargeable battery comprising immobilized selenium is also disclosed herein. The selenium can be doped with other elements, such as, but not limited to, sulfur.

A composite material which contains selenium and carbon is also disclosed herein, which comprises a platelet morphology with an aspect ratio of 1, 2, 5, 10 or 20.

This also discloses a cathode which contains a composite material which comprises selenium and carbon and which has a platelet morphology with an aspect ratio of 1 1, 2, 5, 10 or 20. Also disclosed herein is a rechargeable battery that includes a composite material comprising selenium and carbon and having a platelet morphology with the aspect ratio above.

Also disclosed herein is a rechargeable battery that includes a cathode, an anode, a separator, and an electrolyte. The rechargeable battery can be charged at 0.1C, 0.2C, 0.5C, 1C, 1.5C, 2C, 3C, 4C, 5C, 6C, 7C, 8C, 9C, 10C or faster. The cathode can comprise at least one member of a chalcogen group such as selenium, sulfur, tellurium and oxygen. The anode may comprise at least one element of an alkali metal, alkaline earth metal, and a metal or Group IIIA metals. The separator can comprise an organic or an inorganic separator, the surface of which can optionally be modified. The electrolyte may comprise at least one of an alkali metal, an alkaline earth metal and a metal or group IIIA metals. The solvent in the electrolyte solution can comprise organic solvents, based on carbonate, ether or ester.

The rechargeable battery can have a specific capacity of 400 mAh / g or higher, 450 mAh / g or higher, 500 mAh / g or higher, 550 mAh / g or higher, or 600 mAh / g or higher. The rechargeable battery may be capable of electrochemical cycling for 50 cycles or more, 75 cycles or more, 100 cycles or more, 200 cycles or more, and so on. The rechargeable battery can have a specific capacity of the battery greater than 30%, greater than 40%, greater than 50%, greater than 60%, greater than 70% or greater than 80% of the second specific discharge capacity at a cycling rate of 0.1C performing charge-discharge cycling at a high C rate (e.g. 5 cycles at 0.1C, 5 cycles at 0.2C, 5 cycles at 0.5C, 5 cycles at 1C, 5 cycles at 2C, 5 cycles at 5C and cycles with 10C). The rechargeable battery can have a coulombic efficiency of ≥ 50%, ≥ 60%, ≥ 70%, ≥ 80% or ≥ 90%. The rechargeable battery can be used for electronics, an electric or hybrid vehicle, an industrial application, a military application such as a drone, an aerospace application, a marine application, and so on.

Figure list

• 1 Figure 13 is a 50,000X scanning electron microscope photograph of the carbon material of Example 1;
• 2 Fig. 13 is a 0.1 IC charge and discharge curve of the lithium selenium battery of Example 1;
• 3 Fig. 13 is a 0.1 IC charge and discharge curve of the lithium selenium battery of the comparative example 2 ;
• 4th Fig. 13 is an optical image of a pouch cell battery of Example 1;
• 5 Fig. 13 is a 0.05C charge and discharge curve of the pouch cell battery of Example 1;
• 6 Figure 13 is a flow diagram of a process for making immobilized selenium;
• 7th Fig. 13 is a scanning electron microscope image of a carbon skeleton prepared by the process of Example 9;
• 8th Fig. 14 are X-ray diffraction patterns of the carbon skeleton prepared by the process of Example 9;
• 9 Fig. 13 is a Raman spectrum of the carbon skeleton prepared by the process of Example 9;
• 10A Figure 13 is a graph of cumulative and incremental surface area for the carbon skeleton prepared using the process of Example 9;
• 10B Figure 13 is a graph of cumulative and incremental volume for the carbon skeleton prepared using the process of Example 9;
• 11A Figure 13 is a TGA analysis graph for the immobilized selenium prepared by the process of Example 10;
• 11B Figure 13 is a graph of TGA analysis for non-immobilized selenium samples prepared by the process of Example 10 using Se-Super-P-Carbon and Se-Graphite;
• 11C is a graph of a TGA analysis of the non-immobilized selenium sample obtained using the Se-Super-P carbon ( 11B) under a stream of argon gas and at heating rates of 16 ° C / min. and 10 ° C / min. is prepared;
• 11D Figure 13 is a graph of rate constants for non-immobilized selenium (Se-Super-P composite (solid line) and 2 different samples of immobilized selenium (228-110 (dotted line) and 115-82-2 (dashed line)), as determined by the Process of Example 10 is prepared;
• 12th Fig. 13 is a graph of a Raman spectrum of the immobilized selenium prepared by the process of Example 10;
• 13 Fig. 13 is a graph of X-ray diffraction patterns for the immobilized selenium prepared by the process of Example 10;
• 14th Fig. 10 is an SEM image of the immobilized selenium prepared by the process of Example 10;
• 15th Fig. 13 is an exploded view of a coin cell battery including a cathode prepared according to the process of Example 11 or Example 13;
• 16 are graphs of cycling test results for a first lithium selenium button cell battery (0.1C) ( 16A - left) and a second lithium selenium button cell battery (0.1C and then 1C) ( 16A - right) of the type in 15th prepared using the process of Example 12;
• 17th are graphs of cycling tests for a lithium selenium button cell battery of the type shown in 15th is shown prepared using the process of Example 12 at different cycling rates;
• 18th are graphs of 0.1C cycling test results for a lithium-sulfur-doped selenium button cell battery of the type shown in 15th shown made in accordance with Example 13 with a polymer separator;
• 19th are graphs of the 1C cycling test results for a lithium-sulfur doped selenium button cell battery of the type shown in 15th made in accordance with Example 13 with a polymer separator.
• 20th are SEM images of a three-dimensional porous carbon nanomaterial with interconnected thin walls made from glucose;
• 21st are BET-N ₂ isotherms (a) and a pore size distribution (c) for three-dimensional porous carbon nanomaterials with interconnected thin walls that are produced from glucose;
• 22nd are SEM images of a three-dimensional porous carbon nanomaterial with interconnected thin walls made from soy flour; and;
• 23 are BET-N ₂ isotherms (b) and pore size distributions (d) for three-dimensional porous carbon nanomaterials with interconnected thin walls made from soy flour.

DESCRIPTION OF THE INVENTION

In connection with the specific examples, the present invention is further described below. Unless otherwise specified, the experimental procedures in the following examples are all conventional; the reagents and materials are all available from commercial sources.

Example 1:

Preparation of selenium-carbon composite material

After crushing and grinding, an appropriate amount of potassium citrate is calcined at 800 ° C. for 5 hours under an inert atmosphere and cooled to room temperature. It is washed to neutral pH with dilute hydrochloric acid; filtered and dried to give a two-dimensional carbon nanomaterial (1); according to the mass ratio 50:50, the two-dimensional Carbon material and selenium weighed, and then stirred and mixed with the selenethanol solution uniformly; after evaporation of the solvent, the mixture is dried in a drying oven; the dried mixture was at 5 ° C / min. heated to 240 ° C and warmed through for 3 hours; then continue at 5 ° C / min. heated to 450 ° C; Soaked for 20 hours, cooled to room temperature, resulting in the selenium-carbon composite material.

Preparation of the selenium-carbon composite material cathode

The selenium-carbon composite materials prepared above are mixed with Carbon Black Super P (TIMCAL) and binder CMC / SBR (weight ratio: 1: 1) together with water by means of a fixed formulation by crushing, coating, drying and other procedures to obtain a selenium -Carbon composite material cathode.

Put together lithium selenium battery

The selenium-carbon composite material cathode prepared above, lithium foil as anode, Celgard membrane as separator and 1M LiPF ₆ in EC / DMC as the electrolyte were assembled into a lithium-selenium button cell battery and a lithium-selenium pouch cell battery ( 4th ).

Lithium selenium battery test

A charge-discharge device is used to perform a constant current charge-discharge test on the lithium selenium button cell battery and the lithium selenium pouch cell battery. The test voltage range is 1.0-3.0 V and the test temperature is 25 ° C. The specific discharge power and the level of the charge-discharge current are calculated based on the selenium mass according to the standard. The charge-discharge current is 0.1C or 0.05C. The lithium selenium button charge and discharge curve is in 2 The specific test results are shown in Table 1 below. The lithium selenium pouch cell test results are in 5 shown.

Example 2:

The conditions are the same as in Example 1, except that the raw material that is carbonized for the two-dimensional carbon is sodium citrate. The battery test results are summarized in Table 1 below.

Example 3:

The conditions are the same as in Example 1, except that the raw material that is carbonized for the two-dimensional carbon is potassium gluconate. The battery test results are summarized in Table 1 below.

Example 4:

The conditions are the same as in Example 1, except that the high temperature carbonization temperature for the carbon material is 650 ° C. The battery test results are summarized in Table 1 below.

Example 5:

The conditions are the same as in Example 1, with the exception that the dried mixture at 5 ° C / min. heated to 300 ° C and warmed through at this temperature for 3 hours. The battery test results are summarized in Table 1 below.

Example 6:

The conditions are the same as in Example 1, with the exception that the dried mixture at 5 ° C / min. heated to 240 ° and warmed through at this temperature for 3 hours, then further heated to 600 ° C and warmed through at this constant temperature for 20 hours. The battery test results are summarized in Table 1 below.

Example 7:

The conditions are the same as in Example 1, except that the lithium Se battery was packed with a lithiated graphite anode in place of the lithium anode sheet. The battery test results are summarized in Table 1 below.

Example 8:

The conditions are the same as in Example 1, except that the lithium Se battery was packed with a lithiated silicon-carbon anode in place of the lithium anode sheet. The battery test results are summarized in Table 1 below.

Comparative example 1:

The conditions are the same as in Example 1, except that polyacrylonitrile is used as the raw material. The battery test results are summarized in Table 1 below.

Comparative example 2:

The conditions are the same as in Example 1; except that a one-step composite process is used to prepare the selenium and carbon composite. In this example, the dried selenium-carbon mixture at 5 ° C / min. Heated to 500 ° C and warmed through at this temperature for 23 hours in order to obtain selenium-carbon composite material. The charge-discharge curve of a battery made from the selenium-carbon composite material thus obtained is shown in FIG 3 shown; the battery test results are summarized in Table 1 below. Table 1 - Summarized Battery Test Results numbering The discharge capacity of the first cycle (mAh / g) The charge capacity of the first cycle / the discharge capacity of the first cycle (%) The capacity of the 50th cycle (mAh / g) example 1 1050 78.1 756 Example 2 940 74.6 672 Example 3 962 75.3 683 Example 4 987 72.1 680 Example 5 936 73.2 653 Example 6 972 70 661 Example 7 836 72.5 580 Example 8 910 73 600 Comparative example 1 635 55 350 Comparative example 2 980 40.8 386

After describing a method for producing a selenium-carbon composite material, a method for producing immobilized selenium and the use of the immobilized selenium in, for example, a rechargeable battery will be described.

Selenium is an element in the same group as oxygen and sulfur, namely group 6 of the table of the periodic table. Selenium can be advantageous over oxygen and sulfur in terms of its substantially high electrical conductivity. US 2012/0225352 discloses making rechargeable Li-selenium and Na-selenium batteries with good capacity and cycling ability. However, a certain level of polyselenide anions oscillates between the cathodes and anodes of such batteries, which results in additional electrochemical performances which must be improved considerably for practical uses. Literature relevant to this area includes:

"Electrode Materials for Rechargeable Batteries", Ali Aboulmrane and Khalil Amine, US patent application 2012/0225352 , September 6, 2012.

"Lithium-Selenium Secondary Batteries Having non-Flammable Electrolyte", Hui He, Bor Z. Jang, Yanbo Wang and Aruna Zhamu, US patent application 2015/0064575 , March 5, 2015.

"Electrolyte Solution and Sulfur-based or Selenium-based Batteries including the Electrolyte Solution", Fang Dai, Mei Cai, Qiangfeng Xiao and Li Yang, US patent application 2016/0020491 , January 21, 2016.

"A New Class of Lithium and Sodium Rechargeable Batteries Based on Selenium and Selenium-Sulfur as a Positive Electrode", Ali Abouimrane, Damien Dambournet, Kerena W. Chapman, Peter J. Chupa, Wei Wang and Khalil Amine, J. Am. Chem. Soc. 2012, 134, 4505-4508 .

"A Free-Standing and Ultralong-life Lithium-Selenium Battery Cathode Enabled by 3D Mesoporous Carbon / Graphene Hierachical Architecture", Kai Han, Zhao Liu, Jingmei Shen, Yuyuan Lin, Fand Dai and Hongqi Ye, Adv. Funct. Mater., 2015, 25, 455-463 .

"Micro- and Mesoporous Carbide-Derived Carbon-Selenium Cathodes for High-Performance Lithium Selenium Batteries", Jung Tai Lee, Hyea Kim, Marin Oschatz, Dong-Chan Lee, Feixiang Wu, Huan-Ting Lin, Bogdan Zdyrko, Wan I1 Chao , Stefan Kaskel and Gleb Yushin, Adv. Energy Mater. 2014, 1400981 .

"High-Performance Lithium Selenium Battery with Se / Microporous Carbon Composite Cathode and Carbonate-Based Electrolyte", Chao Wu, Lixia Yuan, Zhen Li, Ziqi Yi, Rui Zeng, Yanrong Li and Yunhui Huang, Sci. China Mater. 2015, 58 , 91-97 .

"Advanced Se-C Nanocomposites: a Bifunctional Electrode Material for both Li-Se and Li-ion Batteries", Huan Ye, Ya-Xia Yin, Shuai-Feng Zhang and Yu-Guo Guo, J. Mater. Chem. A., May 23, 2014 .

"Lithium Iodide as a Promising Electrolyte Additive for Lithium-Sulfur Batteries: Mechanisms of Performance Enhancement", Feixiang Wu, Jung Tae Lee, Naoki Nitta, Hyea Kim, Oleg Borodin and Gleb Yushin, Adv. Mater. 2015, 27, 101-108 .

"A Se / C Composite as Cathode Material for Rechargeable Lithium Batteries with Good Electrochemical Performance", Lili Li, Yuyang Hou, Yaqiong Yang, Minxia Li, Xiaowei Wang and Yuping Wu, RSC Adv., 2014, 4, 9086-9091 .

"Elemental Selenium for Electrochemical Energy Storage", Chun-Peng Yang, Ya-Xia Yin and Yu-Guo Guo, J. Phys. Chem. Lett. 2015, 6, 256-266 .

"Selenium @ Mesoporous Carbon Composite with Superior Lithium and Sodium Storage Capacity", Chao Luo, Yunhua Xu, Yujie Zhu, Yihang Liu, Shiyou Zheng, Ying Liu, Alex Langrock and Chunsheng Wang, ACSNANO, Volume 7, No. 9, 8003- 8010 .

Immobilized selenium comprising selenium and carbon is also disclosed herein. Immobilized selenium can have an elemental form of selenium or a selenium mixture form. Selenium can be doped with another element such as, but not limited to, sulfur. The immobilized selenium enables the location of elementary selenium atoms that function properly electrochemically without oscillating between a cathode and anode of a battery. Immobilizing selenium enables an elementary selenium atom to gain two electrons during a discharge process and to form a selenium anion at the point where the selenium molecule / atom is immobilized. The selenium anion can then donate two electrons during a charging process to form an elementary selenium atom. Immobilized selenium can thus function as an electrochemical active agent for a rechargeable battery that has a specific capacity that can go up to a stoichiometric level, a coulombic efficiency that can be ≥ 95%, ≥ 98% or up to 100% and can achieve significantly improved long-term cycling ability.

In a battery made with immobilized selenium, the electrochemical behaviors of elemental selenium atoms and selenide anions during charging are processes that are desirable to function properly. Carbon skeletons that have Sp ² carbon-carbon bonds have delocalized electrons which, via a conjugated six-membered ring, carry aromatic π- Bonds are shared through local graph-like G-band networks bound by D-band carbon. If there is an electrical potential, such delocalized electrons can flow over the carbon structure with little or no electrical resistance. Selenium immobilization can also compress the Sp ² carbon-carbon bonds of a carbon backbone, resulting in stronger carbon-carbon bonds, possibly leading to improved electronic conductivity within the carbon-backbone network. At the same time, the selenium immobilization can also lead to the compression of selenium particles, which results in stronger chemical and physical selenium-selenium interactions, which possibly lead to improved electrical conductivity among immobilized selenium particles. When both carbon-carbon bonds and Se-Se bonds are improved due to selenium immobilization, carbon-selenium interactions are also improved by the compression, in addition to having a stabilized portion of selenium to which the carbon skeleton can bind. This segment of selenium can act as an interface layer for a carbon scaffold to successfully immobilize the stabilized selenium segment. Electrons can consequently flow in the carbon skeleton and the immobilized selenium, whereupon the electrochemical charge / discharge processes can function efficiently in a rechargeable battery. This in turn allows the rechargeable battery to maintain near stoichiometric specific capacity and have the ability to cycle at almost any practical rate with a low level of degradation in the electrochemical performance of the battery.

A carbon framework can be porous and can be doped with a different composition. The pore size distributions of the carbon skeleton can range from sub-angstroms to a few micrometers or up to a pore size that can be characterized by a pore size distribution instrument using nitrogen, argon, CO ₂ or some other absorbent as the test molecule. The porosity of the carbon skeleton can comprise a pore size distribution that reaches a peak value in the range of at least one of the following: between sub-angstroms and 1000 angstroms or between one angstrom and 100 angstroms or between one angstrom and 50 angstroms or between one angstrom and 30 Ångström and or between one Ångström and 20 Ångström. The porosity of the carbon skeleton may further comprise pores which have a pore size distribution with more than one peak in the regions described in the explanation above. Immobilized selenium can favor a carbon scaffold that has small pore sizes in which electrons are quickly delivered and recovered with minimal electrical resistance, which can allow selenium to function better electrochemically in a rechargeable battery. The small pore size can also provide more carbon skeleton surface, wherein the first section of the selenium can form a first interface layer for a second section of selenium immobilization. Additionally, the presence in a carbon skeleton that has a certain proportion of medium-sized pores and a certain proportion of large-sized pores can also be beneficial for effective delivery of solvent lithium ions from bulk solvent media to an area with small pores where lithium ions can lose their coordinated solvent molecules and are transported in lithium selenide solid phase.

The pore volume of the carbon skeleton can be as low as 0.01 ml / g and as high as 5 ml / g or can be between 0.01 ml / g and 3 ml / g or can be between 0.03 ml / g and 2, 5 ml / g or can be between 0.05 ml / g and 2.0 ml / g. The pore volume, which has pore sizes smaller than 100 Å or smaller than 50 Å, or smaller than 30 Å or smaller than 20 Å, can be larger than 30% or larger than 40% or larger than 50% or larger than 60% or larger than 70% or greater than 80% of the total measurable pore volume that can be measured using a BET instrument with nitrogen, CO ₂ , argon and other test gas molecules. The surface area of the carbon determined by BET can be greater than 400 m ² / g or greater than 500 m ² / g or greater than 600 m ² / g or greater than 700 m ² / g or greater than 800 m ² / g or greater than 900 m ² / g or greater than 1000 m ² / g.

The carbon can also be substantially amorphous or it can have a very broad peak feature centered at a d-spacing around 5 angstroms.

The carbon may comprise Sp ² carbon-carbon bonds that have Raman peak shifts with a D band and a G band. In one example, the Sp ² carbon-carbon bonds of carbon have a D band centered at 1364 + 100 cm ^-1 with a FWHM about 296 ± 50 cm ^-1 and a G band center at 1589 + 100 cm ^-1 with an FWHM of about 96 + 50 cm ^-1 in the Raman spectrum. The ratio of the area of the D band to that of the G band can range from 0.01 to 100, or from 0.1 to 50, or from 0.2 to 20.

The carbon can have any desired morphology, namely platelets, spheres, fibers, needles, tubes, irregular, contiguous, agglomerated, individual or any solid particles. Plate, fiber, needle, tube, or a morphology that has a certain level of aspect ratio may be beneficial in achieving better contact between particles, resulting in better electrical conductivity, which may improve the performance of the rechargeable battery.

The carbon can have any particle size, with an average particle size from a nanometer to a few millimeters, or from a few nanometers to less than 1000 micrometers, or from 20 nm to 100 micrometers.

The property of a carbon skeleton can affect selenium immobilization, and interactions between the carbon skeleton surface and the selenium particles can affect the performance of a rechargeable battery. The location of Sp ² carbon in a carbon backbone can help achieve Se immobilization. Sp ² carbon from small carbon skeleton pores may be preferred, which can be quantified by the NLDFT surface method as discussed in Example 9 herein. The surface of the carbon skeleton pores less than 20 angstroms may ≥ 500 m ² / g, ≥ 600 m ² / g, ≥ 700 m ² / g, ≥ 800 m ² / g, ≥ 900 m2 / g or ≥ 1,000 m ² / amount g. The surfaces of the carbon skeleton pores between 20 Angstroms and 1000 Angstroms can be 20% or less, 15% or less, 10% or less, 5% or less, 3% or less, 2% or less, or 1% or less of the total surface area of the carbon skeleton turn off.

Immobilized selenium may include selenium that vaporizes at a temperature higher than that of elemental selenium, with reference to the following definition of selenium evaporation: Elemental selenium in a Se-Super-P composite loses 50% of its weight in one Temperature of 480 ° C, elemental selenium in an Se / graphite composite material loses 50% of its weight in contained selenium at a temperature of 471 ° C. Immobilized selenium loses 50% of its weight at a temperature higher than 480 ° C, for example at a temperature ≥ 490 ° C, ≥ 500 ° C, ≥ 510 ° C, ≥ 520 ° C, ≥ 530 ° C, ≥ 540 ° C , ≥ 550 ° C, ≥ 560 ° C, ≥ 570 ° C or ≥ 580 ° C or more. Selenium in the immobilized selenium can have a kinetic energy of ≥ 9.5 kJ / mol, ≥ 9.7 kJ / mol, ≥ 9.9 kJ / mol, ≥ 10.1 kJ / mol, ≥ 10.3 kJ / mol or ≥ 10.5 kJ / mol or more to overcome the connection and / or intermolecular forces in the immobilized selenium system and to escape to the gas phase. In one example, the last portion of the immobilized selenium that evaporates may require kinetic energy of ≥ 11.635 joules / mol (≥ 660 ° C) to escape the carbon framework and may be critical for selenium immobilization and as an interface material between the The carbon skeleton and the majority of the immobilized selenium molecules work. This part of the element, which requires a kinetic energy of ≥ 11.635 Joule / mol, is called interface selenium. The amount of interfacial selenium in the immobilized selenium can be 1.5%, 2.0%, 5% or 3.0% of the total immobilized selenium.

Immobilized selenium may comprise selenium which has an activation energy higher than that for conventional (non-immobilized) selenium to overcome for the selenium to escape from the immobilized Se-C composite material system. The activation energy for non-immobilized selenium (Se-Super-P composite material system) was determined to be about 92 kJ / mol according to the ASTM E1641-16 method. The activation energy for selenium in the immobilized selenium, which comprises selenium and carbon, is ≥ 95 kJ / mol, ≥ 98 kJ / mol, ≥ 101 kJ / mol, ≥ 104 kJ / mol, ≥ 107 kJ / mol or ≥ 110 kJ / mol. The activation energy for selenium in the immobilized selenium comprising selenium and carbon is ≥ 3%, ≥ 6%, ≥ 9%, ≥ 12%, ≥ 15% or ≥ 18% more than for selenium in the Se-Super-P -Composite material. The immobilized selenium may be more persistent than non-immobilized selenium, which is why the battery that includes immobilized selenium is better able to electrochemically cycle, probably due to the minimization (or elimination) of selenium shuttling between the cathode and anode, which the result is that selenium is immobilized in the Se-C composite material.

Immobilized selenium can include selenium that is Raman inactive or Raman active, typically having a Raman peak at 255 ± 25 cm ^-1 or at 255 ± 15 cm ^-1 or at 255 + 10 cm ^-1 . Relative Raman peak strength is defined as the area of the Raman peaks at 255 cm ^-1 with respect to the area of the D-band peak of the carbon Raman spectrum. Immobilized carbon can comprise selenium, which has a relative Raman peak strength of ≥ 0.1%, ≥ 0.5%, ≥ 1%, ≥ 3%, ≥ 5%. Immobilized carbon can contain ≥ 5% selenium, ≥ 10% selenium, ≥ 20% selenium, ≥ 30% selenium, ≥ 40% selenium, ≥ 50% selenium, ≥ 60% selenium or ≥ 70% selenium.

Immobilized selenium can include selenium that is red-shifted from the Raman peak of pure selenium. A redshift is defined by a positive difference between the Raman peak position for the immobilized selenium and that for pure selenium. Pure selenium typically has a Raman peak at around 235 cm ^-1 . Immobilized selenium can include selenium, which has a redshift of the Raman peak by ≥ 4 cm ^-1 ≥ 6 cm ^-1 ≥ 8 cm ^-1 ≥ 10 cm ^-1 ≥ 12 cm ^-1 ≥ 14 cm ^-1 or ≥ 16 cm ^-1 having. A redshift of the Raman peak suggests that there is compression on the selenium particles.

Immobilized selenium can include carbon, which can be under compression. Under compression, electrons can flow with minimal resistance, which facilitates rapid electron delivery to selenium and from selenium anions for electrochemical processes during discharge-charge processes for a rechargeable battery. The D band and / or G band in the Raman spectrum for the Sp ² carbon-carbon bonds of the carbon skeleton, which comprise the immobilized selenium, can have a redshift of ≥ 1 cm ^-1 , ≥ 2 cm ^-1 , ≥ 3 cm ^-1 , ≥ 4 cm ^-1 or ≥ 5 cm ^-1 .

Immobilized selenium includes selenium, which may have a higher shock frequency than non-immobilized selenium. Such a high shock frequency can result from the fact that selenium is under compression in the immobilized Se-C system. The collision frequency for selenium in unimmobilized selenium was determined to be 2.27 × 10 ⁵ according to the ASTM E1641-16 method. The collision frequency for selenium in the immobilized selenium comprising selenium and carbon is ≥ 2.5 × 10 ⁵ , ≥ 3.0 × 10 ⁵ , ≥ 3.5 × 10 ⁵ , ≥ 4.0 × 10 ⁵ , ≥ 4 , 5 × 10 ⁵ , ≥ 5.0 × 10 ⁵ , ≥ 5.5 × 10 ⁵ , ≥ 6.0 × 10 ⁵ or ≥ 8.0 × 10 ⁵ . The immobilized selenium can have a shock frequency ≥ 10%, ≥ 30%, ≥ 50%, ≥ 80%, ≥ 100%, ≥ 130%, ≥ 150%, ≥ 180% or ≥ 200% higher than that for non-immobilized selenium in have the Se-C composite material. This can lead to better electron conductivity in the immobilized selenium system due to more collisions among selenium species. The immobilized selenium in Se-C composite would also have a higher frequency of impact against the wall of the carbon host (e.g. a carbon skeleton), which can result in better electron delivery or electron recovery from the carbon skeleton during electrochemical cycling, resulting in a battery (the immobilized selenium) that has improved cycling performance, such as achieving more cycles or cycling at a much higher C-rate, which is highly desirable.

Immobilized selenium includes selenium, which has less of a tendency to leave its host material (carbon) because it has a kinetic rate constant that is ≤ 1: 5, ≤ 1:10, ≤ 1:50, ≤ 1: 100, ≤ 1 : 500 or ≤ 1: 1000 of the kinetic rate constant for non-immobilized / conventional selenium. In our example, the immobilized selenium comprises selenium, which has less of a tendency to leave its host material (carbon) because it has (at 50 ° C) a kinetic rate constant of ≤ 1 × 10 ^-10 , ≤ 5 × 10 ^-11 , ≤ 1 × 10 ^-11 , ≤ 5 × 10 ^-12 or ≤ 5 × 10 ^-13 .

Immobilized selenium can include selenium, which can be amorphous as determined by x-ray diffraction measurements. A diffraction peak that has ad spacing of about 5.2 angstroms is relatively smaller or weaker, for example 10% weaker, 20% weaker, 30% weaker or 40% weaker than that for the carbon skeleton.

Immobilized selenium can be prepared by physically mixing carbon and selenium, followed by melting and homogenizing (or mixing or blending) selenium molecules to achieve selenium immobilization. Physical mixing can be achieved by ball milling (dry or wet), mortar and pestle (dry or wet) mixing, jet milling, horizontal milling, attritor milling, high shear mixing in slurries, conventional slurry mixing with a blade, etc. The physically mixed mixture of selenium and carbon can be heated to a temperature which is at or above the melting point of selenium and lower than the melting point of carbon. The heating can be carried out in an inert gas environment such as, but not limited to, argon, helium, nitrogen, etc. The heating environment can include air or a reactive environment. Immobilization of selenium can be achieved by impregnating dissolved selenium in carbon followed by evaporation of the solvent. The solvent for dissolving selenium may include an alcohol, an ether, an ester, a ketone, a hydrocarbon, a halogenated hydrocarbon, a nitrogen-containing composite material, a phosphorus-containing composite material, a sulfur-containing composite material, water, and so on.

Immobilized selenium can be achieved by melting a large amount of selenium in the presence of carbon followed by removal of excess, non-immobilized selenium.

An immobilized selenium system or an immobilized selenium mass can comprise immobilized selenium with 30%, 40%, 50%, 60%, 70%, 80% or 90% of the total amount of selenium in the system or the mass. The non-immobilized selenium can evaporate at a temperature lower than that of the immobilized selenium.

An immobilized selenium system or an immobilized selenium mass can comprise immobilized selenium which is doped with one or more additional / other elements of group 6 of the table of the periodic table, such as sulfur and / or tellurium. The dopant level can range from as low as 100 ppm by weight to as high as 85% of the weight of the immobilized selenium system or mass of selenium.

An exemplary process for making immobilized selenium is in 6 illustrated. In the process, selenium and carbon are mixed together under dry or wet conditions ( S1 ). The mixture can optionally be dried to a powder ( S2 ), followed by optional pelletizing of the dried powder ( S3 ). The results of the step S1 and optionally the steps S2 and S3 result in a carbon skeleton that is a starting material for step S4 is. At step S4 Selenium is melted into the carbon structure. It will allow the selenium that is melted into the carbon backbone to dry, thereby immobilizing the selenium of the step S5 is produced. The preparation and characterization of the immobilized selenium are described below in connection with Example 10.

The immobilized selenium can be used as a cathode material for a rechargeable battery. To make a cathode, the immobilized selenium can be dispersed in a liquid medium, such as, but not limited to, water or organic solvent. The cathode comprising the immobilized selenium may comprise a binding agent, optionally another binding agent, optionally an electrical conductivity promoter and a current charge collector. The binder can be organic or organic. An organic binder can consist of a natural product such as CMC or a synthetic product such as an SBR rubber latex. An electrical conductivity promoter can be a type of carbon such as small particles derived from graphite, graphene, carbon nanotubes, carbon nanosheet, carbon black, etc. An electrical charge collector can be, for example, an aluminum foil, a copper foil, a carbon foil, a carbon cloth or other metallic foils his. The cathode can be by coating an immobilized selenium-containing slurry (or slurry) on the charge collector, followed by a typical drying process (air drying, oven drying, vacuum oven drying, etc.). The immobilized selenium slurry or slurries can be prepared by a high-shear mixer, a conventional mixer, a planetary mixer, a double planetary mixer, a ball mill, a vertical attritor, a horizontal mill, and so on. The cathode, which comprises immobilized selenium, can be pressed or roll milled (or calendered) prior to use in a battery assembly.

A rechargeable battery that includes immobilized selenium may include a cathode that includes immobilized selenium, an anode, a separator, and an electrolyte. The anode can comprise lithium, sodium, silicon, graphite, magnesium, tin and / or a desirable element and / or a desirable element or a combination of elements from Group IA, Group IIA, Group IIIA, etc. of the table of the periodic table. The separator can comprise an organic separator, an inorganic separator or a solid electrolyte separator. An organic separator can comprise a polymer such as polyethylene, polypropylene, polyester, a halogenated polymer, a polyether, a polyketone, etc. An inorganic separator can comprise a glass or quartz fiber, a solid electrolyte separator. An electrolyte may include a lithium salt, a sodium salt or other salt, a Group IA salt of the Periodic Table, a Group IIA salt of the Periodic Table, and an organic solvent. The organic solvent may include an organic carbonate mixture, an ether, an alcohol, an ester, a hydrocarbon, a halogenated hydrocarbon, a lithium-containing solvent, and so on.

A rechargeable battery comprising immobilized selenium can be used for electronics, an electric or hybrid vehicle, an industrial application, a military application such as a drone, an aerospace application, a marine application, and so on.

A rechargeable battery comprising immobilized selenium can have a specific capacity of 400 mAh / g active amount of selenium or higher, 450 mAh / g or higher, 500 mAh / g or higher, 550 mAh / g or higher, or 600 mAh / g or higher exhibit. A rechargeable battery, the immobilized selenium may be capable of electrochemical cycling for 50 cycles or more, 75 cycles or more, 100 cycles or more, 200 cycles or more, and so on.

A rechargeable battery comprising immobilized selenium may be capable of charging 0.1C, 0.2C, 0.5C, 1C, 1.5C, 2C, 3C, 4C, 5C, 6C, 7C, 8C, 9C, 10C or to be loaded faster. After performing extensive charge-discharge cycling at the high C rate for 30 or more cycles (e.g. 5 cycles at 0.1C, 5 cycles at 0.2C, 5 cycles at 0.5C, 5 cycles at 1C, 5 Cycles at 2C, 5 cycles at 5C and 5 cycles at 10C), a rechargeable battery comprising immobilized selenium can have a specific battery capacity> 30%,> 40%,> 50%,> 60%,> 70%,> 80 % of the 2nd specific discharge capacity retained at a cycling rate of 0.1C.

Several examples follow below to illustrate the spirit of the inventions. However, these examples should not be construed in a limiting sense.

EXAMPLES

Characterization method

Scanning electron microscopy (SEM) images were collected on a Tescan Vega scanning electron microscope equipped with an energy dispersive analysis x-ray detector (EDX detector).

Raman spectra were collected with a Renishaw-in-Via (confocal) Raman microscope. Laser Raman spectroscopy is widely used as a standard for the characterization of carbon and diamond and provides readily distinguishable signatures of each of the different forms (allotropes) of carbon (e.g. diamond, graphite, buckyballs, etc.). Combined with photoluminescence (PL) technology, it offers a non-destructive way of examining various properties of a diamond, including phase purity, crystal size and orientation, defect level and structure, impurity type and concentration, and stress and strain. In particular, the width (full half-width, FWHM) of the Raman diamond peak at 1332 cm ^-1 , as well as the Raman strength ratio between diamond peak and graphitic peaks (D band at 1350 cm ^-1 and G band at 1600 cm ^{- 1} ), is a direct indicator of diamond quality or the quality of other carbon material. Furthermore, stress and strain levels in diamond or other carbon grains and foils can be estimated from the Raman diamond peak shift. It has been reported that the Raman diamond peak displacement rate under hydrostatic stress is about 3.2 cm ^-1 / GPa, with a peak shift to a lower wavenumber under tensile stress and a higher wavenumber under compressive stress. The Raman spectra discussed herein were collected using a Renishaw-in-Via Raman spectroscope with an excitation laser at 514 nm. More information on the use of Raman spectroscopy to characterize diamond is also in the references (1) AM Zaitsev, Optical Properties of Diamond, 2001, Springer and (2) S. Prawer, RJ Nemanich, Phil. Trans. R. Soc. Lond. A (2004) 362, 2537-2565 , available.

The data for BET surface and pore size distributions of carbon samples were measured by nitrogen absorption and CO ₂ absorption with a 3Flex (Mircomeritics) equipped with a Smart-VacPrep for sample degassing preparations. The sample is typically degassed in Smart-Vac-Prep at 250 ° C. for 2 hours under vacuum before the CO ₂ and N ₂ absorption measurements. The nitrogen absorption is used to determine the BET surface area. Nitrogen absorption data and CO ₂ absorption data were combined to calculate pore size distributions of a carbon sample. For details on combining both N ₂ and CO ₂ absorption data to determine pore size distributions for carbon materials, see "Dual Gas Analysis of Microporous Carbon Using 2D-NLDFT Heterogeneous Surface Model and Combined Adsorption Data of N ₂ and CO ₂ ", Jacek Jagiello, Conchi Ania, Jose B. Parra and Cameron Cook, Carbon 91, 2015, pages 330-337 , draw.

The data for thermogravimetric analysis (TGA) and dynamic differential calorimetry (DSC) for samples from immobilized selenium and the control samples were measured with the Netzsch Thermal Analyzer. The TGA analysis was performed under an argon flow rate of -200 ml / min., A heating rate of 16 ° C / min., 10 ° C / min., 5 ° C / min., 2 ° C / min., 1 ° C / Min. and other heating rates. In terms of consistency, a typical amount of immobilized selenium sample for TGA analysis was about 20 mg.

Activation energy and shock frequency of the immobilized selenium and non-immobilized selenium were determined by TGA following the procedures described in ASTM E1641-16.

X-ray diffraction results for different carbon, Se-carbon samples and immobilized selenium were collected on a Philip diffractometer.

Battery cycling performance for rechargeable batteries comprising immobilized selenium was tested on a Lanhe CT2001A battery cycling tester. Charge and discharge currents of the rechargeable batteries including immobilized selenium were determined by an amount of selenium contained in the immobilized selenium and a cycling rate (0.1C, 0.5C, 1C, 2C, 3C, 4C, 5C, 10C, etc. .) certainly.

Example 9: Synthesis and characterization of a carbon skeleton

To form an initial residue, a batch of 260 grams of potassium citrate was placed in a crucible and the crucible was placed in a quartz tube inside a tube furnace. A stream of argon gas was admitted into the furnace and the furnace was started at 5 ° C / min. heated from room temperature (~ 20 to 22 ° C) to 600 ° C. The furnace was held at this temperature for 60 minutes with a shutdown of the furnace and removal of the batch from the crucible after the furnace had cooled to yield 174.10 grams of processed residue. To form the second and third processed residues, the same process as that described for the first residue was repeated separately for batches of 420 and 974 grams of potassium citrate. The resulting second and third processed residues weighed 282.83 grams and 651.93 grams, respectively.

1108.9 grams from these three processed residues were combined in a crucible that was placed in the quartz tube inside the tube furnace and a flow of argon gas was admitted into the furnace. The oven was running at 5 ° C / min. heated to 800 ° C. The oven was held at 800 ° C for 1 hour. The furnace was allowed to cool, after which the crucible was removed from the quartz tube, and then 1085.74 grams of an initial final residue was recovered.

Then, following the same procedure as in this example (800 ° C), a batch of 120 grams of potassium residue introduced into the oven yielded about 77 grams of a second final residue (800 ° C).

The combination of the first and second final residues resulted in approximately 1163 grams of a third final residue.

The 1163 grams of the third final residue was then mixed with 400 ml of water to form a slurry which was approximately evenly separated into four two liter beakers. The pH of each slurry was determined to be greater than 13 by measurement. Thereafter, a concentrated hydrochloric acid solution was added to each beaker with a violent evolution of carbon dioxide, which precipitated with a pH less than about 5. More hydrochloric acid solution was added to maintain a pH of about 1.9. These slurries were then filtered and washed into filter cakes which were dried in an oven at 120 ° C for about 12 hours, followed by vacuum drying at 120 ° C for 24 hours, resulting in four carbon skeleton samples totaling about 61.07 grams.

These carbon framework samples were characterized using SEM, XRD, Raman, BET / pore size distributions. The SEM result for a carbon skeleton is in 7th shown. Surface morphologies of typical carbon skeleton particles prepared in the process described in this example had sheet-like morphology associated with their sheet edges, with sample thicknesses between 500 nm and 100 nm, and the sample width (or length) between 0.5 and 2 µm, consequently with an aspect ratio (defined as the ratio of the longest dimension of the sample width (or layer length) to the sample thickness ≥ 1, for example with an aspect ratio ≥ 5 or larger or an aspect ratio ≥ 10.

X-ray diffraction pattern of a carbon skeleton shown in 8th show that the carbon skeleton is essentially in the amorphous phase. However, this shows a broad diffraction peak centered at 20 from about 17 °, giving a d-spacing of about 5.21 angstroms.

Raman scattering spectroscopy results for a carbon backbone are in 9 showing Sp ² carbon having a D band at about 1365 cm ^-1 (curve 1) and G band at about 1589 cm ^-1 (Curve 2) with a FWHM of 296 or 96 cm ^-1 . Both the D-band and the G-band show a mixture of Gaussian and Lorenz distributions; the D band has about 33% Gaussian distributions and the G band has about 61% Gaussian distributions. The ratio of the area for the D band to the area for the G band is about 3.5.

The BET surface area of the carbon skeleton was measured to be 1,205 m ² / g by nitrogen absorption. The incremental pore surface area compared to the pore size is in 10A using the NLDFT method and shows a cumulative pore surface area of 1,515 m ² / g. The discrepancy between the BET surface area and the NLDFT surface area may arise from the fact that NLDFT distributions are calculated using both nitrogen and CO ₂ absorption data; CO ₂ molecules can penetrate into the pores, which are smaller than the pores into which nitrogen molecules can penetrate. The NLDFT surface area in the pores, peaking at 3.48 angstroms, is 443 m ² / g, is 859 m ² / g at 5.33 angstroms, and is 185 at 11.86 angstroms (up to 20 angstroms) m ² / g, a total of 1,502 m ² / g for the pores at 20 Angstroms or smaller, while the NLDFT surface area of the pores between 20 Angstroms and 1000 Angstroms is only 7.5 m ² / g, and the surface area of the pores to 20 Angstroms or greater is only about 0.5% of the total surface.

The pore size distributions of the carbon skeleton sample were determined by nitrogen absorption and CO ₂ absorption. The absorption results of nitrogen absorption and CO ₂ absorption were combined to obtain the pore size distribution shown in 10B is shown to generate. The relationship between incremental pore volume (ml / g) versus pore size (Angstroms) shows that there are three large peaks located at 3.66 Angstroms, 5.33 Angstroms and 11.86 Angstroms; the relationship of the cumulative pore volume (ml / g) versus the pore width (Angstroms) shows that there are about 0.080 ml / g pores below the peak of 3.66 Angstroms, about 0.240 ml / g pores below the peak of 5.33 Angstroms, about 0.108 ml / g pores below the peak of 11.86 Angstroms, with 0.43 ml / g pores being 20 Angstroms or smaller, 0.042 ml / g pores between 20 and 100 Angstroms, and a sum of 0.572 ml / g pores up to 1000 angstroms.

Example 10: Preparation and characterization of immobilized selenium

Place 0.1206 grams of selenium (with bulk properties of selenium) in an agate grater and mortar pestle set, and add 0.1206 grams of the carbon framework prepared in accordance with Example 9 to the same agate grinder and mortar pestle. Grind the mixture of selenium and carbon skeleton by hand for about 30 minutes and transfer the milled mixture of selenium and carbon skeleton into a stainless steel mold (10 mm diameter). Press the mixture into the die at a pressure of about 10 MPa to form a pellet of the mixture. Then load the pellet into a sealed container in the presence of an inert environment (argon) and place the sealed container containing the pellet in an oven. Heat the furnace containing the sealed container containing the pellet to 240 ° C (above the melting temperature of selenium) for, for example, 12 hours. However, any combination of time and temperature above the melting temperature of selenium is contemplated that is sufficient to cause selenium and carbon to react, either partially or completely, to form immobilized selenium which has some or all of the characteristics present therein Application are described, has. The pellet is then removed from the container after allowing the pellet to cool to room temperature. The removed pellet is the immobilized selenium of this Example 10.

The immobilized selenium of this example 10 was characterized by TGA-DSC and TGA. The TGA-DSC analysis results were for the immobilized selenium under an argon gas flow of 200 ml / min. at a heating rate of 10 ° C / min. collected. There is no noticeable endothermic DSC peak at temperatures near the melting point of selenium (about 230 ° C) indicating that the immobilized selenium of this Example 10 is different from the bulk form of selenium molecules / atoms which have a melting point of about 230 ° C at which an endothermic peak should occur.

Research has shown that the TGA-DSC data may not be reliable if the heating temperature reaches a point where selenium molecules begin to leak out of the TGA-DSC sample crucible (graphite or ceramics). To this end, selenium molecules (from the sample crucible) enter the argon carrier gas stream in gas phase and appear to react with the TGA-DSC platinum sample holder, distorting actual TGA-DSC thermochemical behaviors. Since the released selenium molecules from the sample crucible react with the platinum sample holder, this leads to less weight loss in this temperature range. The selenium-platinum composite material in the platinum sample holder is then released in the gas phase when the heating temperature reaches a point that is above 800 ° C. Complete selenium release can occur at 1000 ° C. This investigation consumed the majority of the immobilized selenium sample of this Example 10. Thus, a new sample of the immobilized selenium (~ 16 grams) was prepared using the same process as described above in the initial part of this Example 10.

The thermodynamic behaviors of this new sample of immobilized selenium were investigated by TGA analysis which uses a ceramic sample holder that covers a very small thermocouple that is used for TGA analysis. The TGA analysis results for this new sample of immobilized selenium are in 11A together with the TGA analysis results ( 11B) for selenium-carbon composites (made from 50-50 Se-Super-P-carbon composite and Se-graphite (ground graphite) shown in the same process as the preparation of the immobilized selenium of this Example 10. Super P is a commercially available carbon black which is widely used for the lithium-ion battery industry. The ground graphite was prepared by grinding Poco 2020 graphite. The TGA analysis data is also summarized in Table 2 below. Table 2 Se graphite comp. Se-Super-P-Comp. Immobilized Se in Example 10 Mean weight loss temperature Temperature down at head weight loss Final temperature of the TGA-Expt. Mean weight loss temperature, ° C 471 480 595 660 1000 Mean weight loss temperature, K 744 753 868 933 1273 Kinetic energy, joules / mol 9,278 9,391 10,825 11,635 15,876

Immobilized selenium can have an initial weight loss temperature starting at about 400 ° C, compared to 340 ° C for Se-Super-P carbon composite and the Se-graphite-carbon composite; a midpoint weight loss temperature for immobilized selenium may be about 595 ° compared to 480 ° C for the Se-Super-P carbon composite and 471 ° C for Se-graphite composite; and a major weight loss complete at 544 ° C for Se-super-P carbon composite and Se-graphite composite, and at 660 ° C for the immobilized selenium. The Se-Super-P-carbon composite material and the Se-graphite composite material show less than 0.6% weight loss between 560 ° C and 780 ° C, while the immobilized selenium shows a weight loss of about 2.5% from below Shows major weight loss (∼660 ° C to 1000 ° C). These results suggest that non-immobilized selenium (Se-Super-P-carbon composite material and Se-graphite composite material) has ≤ 1.2% of the total selenium that can escape from the composite material at a temperature of ≥ 560 ° Celsius , while the immobilized selenium comprises about 5.0% of the total selenium that can escape from the carbon skeleton at a temperature of ≥ 660 ° C. The following details are provided to give examples that provide insight into the thermodynamic behaviors. However, these details should not be construed in a limiting sense.

Using the TGA midpoint weight loss temperature data as examples of thermochemical behaviors as the heating temperature increases, the kinetic energy of selenium molecules in the Se-super-P carbon composite and the Se-graphite composite increases to a level at which these selenium molecules have enough energy to overcome the intermolecular interactions among selenium molecules and to escape from the liquid phase of selenium. Here kinetic energy = 3RT / 2, where: R is the gas constant and T is the temperature in Kelvin.

It was observed that the average kinetic energy of selenium molecules for Se-super-P-carbon composite material was measured to be 9,391 joules / mol when the selenium molecules escape from the mixture of Se-super-P-carbon composite material. However, the immobilized selenium must gain more energy in order to have an average kinetic energy of about 10,825 joules / mol for selenium to leave the carbon structure to form gas-phase selenium molecules. It is believed that the selenium in immobilized selenium is chemically either in an atomic form, or as a molecular form, or as any form with selenium and the carbon skeleton beyond intermolecular interactions of selenium can interact. In addition, the last portion of selenium that escapes from the carbon structure between 660 ° C. and 1000 ° C. has an average kinetic energy in the range of 11,635 joules / mol to 15,876 joules / mol or more. This suggests that selenium in the immobilized selenium is more stable than the selenium in conventional selenium-carbon composites. The stabilized selenium in the immobilized selenium of this Example 10 enhances the ability of selenium to remain within the carbon framework either as atomic forms, molecular forms, or in any form during electrochemical processes, such as during the charge and discharge cycling of a rechargeable battery, the consists of immobilized selenium. In one example, this last portion of selenium may require kinetic energy ≥ 11,635 joules / mol (≥ 660 ° C) to escape the carbon backbone and can be critical for selenium immobilization and as an interface material between the carbon backbone and most of the immobilized Selenium molecules work. The proportion of interfacial selenium in the immobilized selenium can be 1.5%, 2.0%, 2.5% or 3.0% of the total immobilized selenium.

11A Also shows the TGA studies immobilized selenium at a heating rate of 16 ° C / min., with a temperature of 628 ° C for the midpoint weight loss of contained selenium. As in 11C shown, the temperature at the midpoint weight loss is the contained Se at a heating rate of 16 ° C / min. for Se-Super-P-carbon composite material 495 ° C. With different heating rates (for example 16 ° C / min., 10 ° C / min., 5 ° C / min., 2.5 ° C / min. And 1 ° C / min.) The activation energy and impact frequency can be determined and using known methods such as ASTM E1641-16 and E2958-14. The temperatures at 15% weight loss for different heating rates are shown in tabular form in Table 3 below. Table 3 β (° C / min.) Temperature (° C) Immobilized Se prepared by the process of Example 10 (228-110) Immobilized Se prepared by the process of Example 10 (155-82-2) Se-Super-P-Comp. 16 590.65 570.13 471.08 10 560.82 544.86 456.61 5 535.57 515.09 413.37 2.5 506.66 493.27 397.21 1 478.48 462.18 365.02 Activation energy, kJ / mol 120.7 120.0 92.3 Shock frequency 12.4 x 10 ⁵ 18.3 × 10 ⁵ 2.27 x 10 5

The activation energy for selenium (non-immobilized or conventional) in the Se-Super-P-carbon composite material was determined to be 92.3 kJ / mol with an impact frequency of 2.27 × 10 ⁵ . The activation energy for selenium in immobilized selenium (228 to 110 above) was also determined to be 120.7 kJ / mol with a collision frequency of 12.4 × 10 ⁵ . In another example of immobilized selenium (155-82-2 above), which was prepared using the same procedures as Example 10, an activation energy of 120.0 kJ / mol and an impact frequency of 18.3 × 10 ^{5 were also} determined by measurement.

wobei k die Geschwindigkeitskonstante ist, E_a die Aktivierungsenergie ist, A die Stoßfrequenz ist, R die Gaskonstante ist, und T die Temperatur in Kelvin ist.The kinetic rate constant for selenium is calculated using the Arrhenius equation, $$k=\mathrm{A.}{e}^{-{\mathrm{E.}}_{\alpha }/\mathrm{R.}T}$$

where k is the rate constant, E _{a is} the activation energy, A is the impact frequency, R is the gas constant, and T is the temperature in Kelvin.

With reference to 11D With the activation energy and impact frequency determined above, the kinetic rate constant was calculated using the Arrhenius equation at different temperatures. 11D shows that non-immobilized selenium (Se-Super-P composite material - solid line) has a much higher rate constant than that for immobilized selenium (228-110 (dotted line) and 115-82-2 (dashed line)), which is four orders of magnitude larger at 35 ° C and about three orders of magnitude larger at 100 ° C. In one example, at 50 ° C the rate constant for non-immobilized selenium (Super P) is 2.668 × 10 ^-10 , while immobilized selenium has a rate constant of 7.26 × 10 ^-14 (155-82-2) and 3.78 × 10 ^-14 (228-110). Selenium, which has a lower kinetic rate constant, has less of a tendency to leave the host material (carbon), resulting in better battery cycling performance.

12th shows the spectrum of the immobilized selenium with Raman peaks of the D band at 1368 cm ^-1 and the G band at 1596 cm ^-1 , with a ratio of the area for the D band to the area for the G band of FIG ,8th. Compared to the Raman spectrum of the carbon backbone shown in 9 , shown, selenium immobilization shifts both Raman peaks to a higher wavenumber, about 3 cm ^-1 redshift for the D band and 7 cm ^-1 redshift for the G band, suggesting that the binding strength of Sp ² -Carbon is amplified in the carbon backbone, with a redshift of about 4 cm ^-1 for the D band and a red shift of about 8 cm ^-1 for the G band. At the same time, the ratio of the area for the D band to the area for the G band also decreased from about 3.4 to 2.8, which suggests that either the D band is relatively weaker or that the G band is relatively stronger becomes. A stronger G band may be desirable because the G band may be related to a type of carbon that allows the carbon backbone to conduct electrons more easily, which may be desirable for electrochemical performance when used in a rechargeable battery. Bulk or pure selenium typically shows a sharp Raman shift peak at around 235 cm ^-1 . For immobilized selenium, the Raman spectrum in 12th a broad Raman peak at about 257 cm ^-1 (~ 12.7% of the G band in area) and a new broad hump at about 500 cm ^-1 (about 3.0% of the G band area). Selenium immobilization is believed to change the Raman characteristics for both the carbon skeleton and selenium, with all Raman peaks shifted to a higher wavenumber, suggesting that both the carbon-carbon Sp ² -Bonds for the carbon skeleton as well as the selenium-selenium bonds of selenium are under compression.

The compression that results from selenium immobilization strengthens both the carbon-carbon Sp ² bonds for the carbon backbone and the Se-Se bonds for selenium, creating stronger selenium-selenium and carbon-selenium interactions. It would therefore require more kinetic energy for selenium to overcome the stronger Se-Se bond and stronger carbon-selenium interactions, which is what the observations in the TGA analysis of the immobilized selenium compared to Se-Super-P composite and Se-graphite -Composite material explained.

Furthermore, the carbon framework under compression would then have a better ability to conduct electrons at the bond level; and under compression, selenium atoms or molecules would also have better ability to conduct electrons.

Stabilized selenium for the immobilized selenium, together with improved electron conductivity via the carbon skeleton and selenium can be desirable in electrochemical processes, such as improved specific capacity for the active material with a minimum level of pendulums, improved cyclability due to immobilization, a capability with a higher level Rate of being charged and discharged, etc. However, this should not be construed in a limiting sense.

X-ray diffraction patterns for the immobilized selenium prepared in accordance with Example 10 presented in 13 show a decrease in the strength of the broad diffraction peak from the carbon backbone with ad spacing at about 5.21 angstroms, only about 1/3 the strength, suggesting that immobilized selenium also renders the carbon backbone more disordered or more damaging the order of the carbon skeleton. In one example, it is believed that this is due to the compressive forces being applied to the carbon-carbon Sp ² bonds.

14th FIG. 13 shows a SEM image for the immobilized selenium prepared in accordance with Example 10 showing layer-like morphologies, same as the image in FIG 7th for the carbon skeleton. Although there is about 50% selenium immobilized in the carbon skeleton, there are no observable selenium particles on the surfaces of the carbon skeleton except that the compounds within the layer have been broken, resulting in many flat layers having high aspect ratios . These layer-like morphologies can be highly desirable for forming aligned coatings that are oriented along the flat layer directions, creating layer surface to layer surface contacts, resulting in improved electrical conductivity within the layer Layer leads, which can result in higher electrical power for electrochemical processes, as with a rechargeable battery.

Example 11: Preparation of the Se cathode

56 mg of the immobilized selenium prepared in accordance with Example 10; 7.04 mg Super-P; 182 µl carboxymethyl cellulose solution (CMC solution) (which contains 1 mg dry CMC for every 52 µl CMC solution); 21.126 µl SBR latex dispersion (which contains 1 mg dry SBR latex for each 6.036 µl SBR latex dispersion); and put 200 µl of deionized water in a mortar with a mortar pestle. Hand grind the particles, binder, and water into a slurry for 30 minutes to create a cathode slurry. The cathode slurry was then applied to one side of a piece of an electrically conductive substrate such as a foil and air dried. In one example, the conductive substrate or foil can be aluminum foil (Al foil). However, this is not to be interpreted in a limiting sense as the use of any convenient and / or desirable electrically conductive material of any shape or form is contemplated. For the purpose of description only, the use of an Al foil to form a selenium cathode is described herein. However, this should not be interpreted in a limiting sense.

The sludge-coated Al foil was then placed in a drying oven and heated to a temperature of 55 ° C. for 12 hours, resulting in a selenium cathode consisting of a dried layer of immobilized selenium on one side of the Al foil where the Al foil on the other side was uncoated, i.e. bare aluminum.

The selenium cathode was then punched into cathode disks, each 10 mm in diameter. Some of these cathode disks have been used as cathodes for rechargeable batteries.

Example 12: Li-Se rechargeable battery assembly and testing

The cathode disks of Example 11 were used to power spiral-wound Li-Se rechargeable batteries in the manner discussed in the example described next and in FIG 15th is shown joining. In this example, a cathode disk was used 4th from Example 11 with 10 mm diameter on a base 2 a button cell made of stainless steel 2032, which is called the positive case of the button cell ("positive case" in 15th ) works with the shift 5 made of immobilized selenium facing up from the base 2 of the positive case away, and with the bare Al side facing and in contact with the base of the positive case. Then became a battery separator 6 (19 mm diameter and 25 micrometers thick) on the top of the cathode disk 4th in contact with the layer 5 placed from immobilized selenium. In one example, the battery separator 6 be an organic separator or an inorganic separator or a solid electrolyte separator. An organic separator can be a polymer such as polyethylene, polypropylene, polyester, a halogenated polymer, a polyether, a polyketone, etc. The inorganic separator can be made of glass and / or quartz fiber.

Then 240 µl of electrolyte were added 7th containing LiPF ₆ (1M) in ethylene carbonate (EC) and dimethyl carbonate (DMC) solution (50 parts by weight each) into the positive housing 2 followed by the placement of a lithium foil disk 8th (15.6 mm diameter and 250 micrometers thick) on one side of the separator 6 who have favourited the cathode disk 4th is opposite. Then a stainless steel (SS) spacer 10 on one side of the lithium foil disc 8th , the separator 6 placed opposite, followed by placing one or more foam discs 12th for example made of nickel on one side of the SS spacer 10 the lithium foil disc 8th are made opposite. The lithium foil 8th , the SS spacer 10 and / or the foam disk 12th can act as an anode. Eventually it became an enclosure 14th , made from 2032 stainless steel 14th , to function as the negative side of the button cell (the "negative case" in 15th ) on one side of the nickel foam disc (s) 12, the SS spacer 10 and the collar of the positive housing 2 opposite, placed. The positive case 2 and the negative case 14th were then sealed together under high pressure, for example 1000 psi. Sealing the positive and negative housing ( 2 , 14th ) under high pressure also caused the stack to be compressed (from bottom to top in 15th ) the cathode disk 4th , the separator 6 who have favourited lithium foil 8th , the SS spacer 10 and the Ni foam disk (s) 12. More than a dozen coin cell batteries have been assembled using the battery separators described above and fiberglass separators. The assembled coin cell batteries were then tested under the following conditions.

Some of the assembled coin cell batteries were tested at charge-discharge rates of 0.1C and 1C using a Lanhe CT2001A battery tester. Each coin cell battery was tested: (1) resting for 1 hour; (2) discharge to 1V; (3) rest for 10 minutes; (4) charge to 3V; (5) rest for 10 minutes; Repeat steps (2) through (5) to repeat the cycling test.

16A (left) shows the cycling test results (313 cycles with a charge-discharge rate of 0.1C) for a button cell made in accordance with Example 12 using the cathode prepared in accordance with Example 11, which demonstrates excellent cycling stability , with a specific capacity of 633.7 mAh / g after 313 cycles, which corresponds to a remaining of 93.4% of the initial specific capacity. The first specific discharge capacity was higher than the stoichiometric value, possibly due to some side reactions on the cathode and anode surfaces. From the second cycle, the specific capacity initially decreased with cycling; however, the specific capacity increased slightly from about 30 cycles to about 120 cycles before becoming stable at about 180 cycles and then decreasing. 16B (right) also shows excellent cycling stability (100 cycles at 0.1C and then 500 cycles at 1C) for another button cell that has a specific capacity of 462.5 mAh / g at the 600th cycle, giving a remaining 66, 0% of the capacity of the 2nd cycle at 0.1C or a remaining 80.3% of the capacity of the 105th cycle at 1C. The Coulomb efficiency can be ≥ 95%, ≥ 98% or even 100%, which suggests that no discernible amount of selenium oscillated between the cathode and anode. It is believed that this electromechanical performance is the results of the immobilized selenium in the cathode, which prevents the selenium from being dissolved and removed from the cathode 14th to the anode 2 to commute.

17th shows cycling test results at different discharge-charge cycling rates (between 0.1C and 10C) for a button cell which was assembled with a polymer separator as described in Example 12. The test protocols were similar to the tests described above, except for the cycling rates (0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 10C); five charge and discharge cycles were performed for each C-rate; then the cycling rate was reset to 0.1C cycle. At the 0.1C rate, the battery exhibited a specific capacity around the stoichiometric value. In addition, the battery exhibited good cycling durability for cycling rates of 0.2C, 0.5C, 1C, and 2C. The battery also exhibited fast charge rates. and discharge capacity, cycled 56% of stoichiometric capacity at 10C rate, although it showed a decreasing specific capacity during cycling. In other words, at the IOC rate, it took the battery 3.3 minutes to charge and discharge to / from a capacity of 56% stoichiometric. A conventional battery would not be expected to survive such a rapid cycling rate.

The Li-Se battery, which includes immobilized selenium, can regain its specific capacity to 670 mAh / g, 98% of its full capacity, when cycled at a 0.1 IC rate at the start of the test. It is believed that (1) the stabilization of selenium in the immobilized selenium cathode prevents selenium from exiting the carbon framework, prevents the selenium from shuttling between the cathode and anode during cycling, allowing the battery to improve Exhibit cycling performance; (2) Sp ² carbon-carbon bonds as well as carbon skeleton, selenium-selenium bonds and carbon-selenium interactions can be under compression, possibly resulting in higher electrical conductivity within the carbon skeleton, within the selenium particles and among the carbon and selenium cut surfaces, which can aid in achieving the observed cycling performance at high C-rates.

The mass of immobilized selenium comprising selenium and carbon prepared in accordance with the concepts described herein can include one or more of the following features:

(a) a kinetic energy that is necessary for a selenium particle to escape the immobilized selenium can be ≥ 9.5 kJ / mol ≥ 9.7 kJ / mol ≥ 9.9 kJ / mol ≥ 10.1 kJ / mol ≥ 10 , 3 kJ / mol or ≥ 10.5 kJ / mol;

(b) a temperature required for a selenium particle to escape the immobilized selenium can be ≥ 490 ° C, ≥ 500 ° C, ≥ 510 ° C, ≥ 520 ° C, ≥ 530 ° C, ≥ 540 ° C, Be ≥ 550 ° C or ≥ 560 ° C;

(c) the carbon may have a surface area (for pores less than 20 angstroms) ² / g of ≥ 500 m, ≥ 600 m ² / g, ≥ 700 m ² / g, ≥ 800 m ² / g, ≥ 900 m ² / g or ≥ 1,000 m ² / g;

(d) the carbon can have a surface area (for pores between 20 Angstroms and 1000 Angstroms) of ≤ 20%, ≤ 15%, ≤ 10%, ≤ 5%, ≤ 3%, ≤ 2%, ≤ 1% of the total surface ;

(e) the carbon and / or the selenium can be under compression. Advantages of immobilized selenium, in which the carbon and / or the selenium are under compression, compared to a carbon-selenium system in which the carbon and / or the selenium are not under compression, can include: improved electron flow, reduced resistance to electron flow or both, which can facilitate electron delivery to selenium and from the selenium anions during charging and discharging of a rechargeable battery having a cathode composed of the immobilized selenium;

(f) the immobilized selenium may comprise selenium which has an activation energy which is higher than that for conventional (non-immobilized) selenium in order for the selenium to escape from the immobilized Se-C composite material system. In one example, the activation energy for non-immobilized selenium (Se-Super-P composite material system) was determined to be 92 kJ / mol according to method ASTM E1641-16. In contrast, the activation energy for selenium in the immobilized selenium comprising selenium and carbon can be 95 kJ / mol, 98 kJ / mol, 101 kJ / mol, 104 kJ / mol, 107 kJ / mol or 110 kJ / mol. In another example, the activation energy for selenium in the immobilized selenium comprising selenium and carbon can be ≥ 3%, ≥ 6%, ≥ 9%, ≥ 12%, ≥ 15% or ≥ 18%> greater than for selenium in FIG the Se-Super-P composite material;

(g) the immobilized selenium may comprise selenium which has a higher collision frequency than non-immobilized selenium. In one example, the shock frequency for non-immobilized selenium was determined to be 2.27 × 10 ⁵ according to the ATSM E1641-16 method. On the other hand, in another example, the collision frequency for selenium in immobilized selenium comprising selenium and carbon may be ≥ 2.5 × 10 ⁵ , ≥ 3.0 × 10 ⁵ , ≥ 3.5 × 10 ⁵ , ≥ 4.0 × 10 ⁵ , ≥ 4.5 × 10 ⁵ , ≥ 5.0 × 10 ⁵ , ≥ 5.5 × 10 ⁵ , ≥ 6.0 × 10 ⁵ or ≥ 8.0 × 10 ⁵ . The immobilized selenium can have a shock frequency ≥ 10%, ≥ 30%, ≥ 50%, ≥ 80%, ≥ 100%, ≥ 130%, ≥ 150%, ≥ 180% or ≥ 200% than that for non-immobilized selenium in a Se -C composite material; and

(h) the immobilized selenium can be selenium which comprises a kinetic rate constant that is ≤ 1: 5, ≤ 1:10, ≤ 1:50, ≤ 1: 100, ≤ 1: 500 or ≤ 1: 1000 of the rate constant for non- immobilized / conventional selenium. In one example, the immobilized selenium may comprise selenium which has a rate constant (at 50 ° C.) of 1 × 10 ^-10 , 5 × 10 ^-11 , 1 × 10 ^-11 , 5 × 10 ^-12 or 5 × 10 ^-13 .

With the carbon and / or selenium of the immobilized selenium under compression, the D band and / or the G band of the Raman spectrum for the Sp ² -CC bonds of the carbon (or carbon skeleton defined by the carbon) of the immobilized selenium demonstrate a (positive) red shift, for example by ≥ 1 cm ^-1 , ≥ 2 cm ^-1 , ≥ 3 cm ^-1 , ≥ 4 cm ^-1 or ≥ 5 cm ^-1 from a carbon starting material.

With the carbon and / or selenium of the immobilized selenium under compression, the selenium can have a (positive) red shift from the Raman peak of pure selenium (235 cm ^-1 ), for example by ≥ 4 cm ^-1 , ≥ 6 cm ^-1 , ≥ 8 cm ^-1 , ≥ 10 cm ^-1 , ≥ 12 cm ^-1 , ≥ 14 cm ^-1 or ≥ 16 cm ^-1 , whereby the redshift may suggest compression on the selenium particles.

The immobilized selenium can be an elemental form of selenium and / or a selenium mixture.

The immobilized selenium, which comprises selenium and carbon, can also be added with one or more additional elements from the group 6 of the table of the periodic table (referred to below as “additional G6 element (s)”), including, for example and without limitation, sulfur and / or tellurium. The dopant level can range from as low as 100 ppm by weight to as high as 85% of the total weight of the immobilized selenium. In one example, the immobilized selenium can comprise 15% to 70% carbon and 30% to 85% selenium and optionally additional G6 element (s). In one example, the immobilized selenium may comprise a mixture of (1) 15% to 70% carbon and (2) 30% to 85% selenium + an additional G6 element (s). In the mixture comprising selenium + an additional G6 element (s), the additional G6 element (s) can constitute between 0.1% and 99% of the mixture and selenium can constitute between 1% and Make up 99.9% of the mixture. However, these areas of selenium + additional / additional G6 element (s) must not be interpreted in a restrictive sense.

The immobilized selenium can contain ≥ 5% selenium, ≥ 10% selenium, ≥ 20% selenium, ≥ 30% selenium, ≥ 40% selenium, ≥ 50% selenium, ≥ 60% selenium, or ≥ 70% or a higher percentage of selenium .

The immobilized selenium may optionally include another element such as sulfur, tellurium, etc.

The immobilized selenium can be Raman-inactive or Raman-active. If it is Raman-active, the immobilized selenium can have a relative Raman peak strength at 255 ± 25 cm ^-1 , at 255 ± 15 cm ^-1 or at 255 ± 10 cm ^-1 .

The immobilized selenium can comprise selenium which has a relative Raman peak strength of 0.1%, 0.5%, 1%, 3% or 5%, here being the relative Raman peak strength is defined as the area of the Raman peak at 255 cm ^-1 with respect to the area of the D band peak of the carbon Raman spectrum.

The carbon comprising the immobilized selenium can be used as a carbon skeleton for selenium immobilization. The carbon backbone can contain Sp ² carbon-carbon bonds with a Raman D band at 1365 + 100 cm ^-1 and G band at 1589 ± 100 cm ^-1 ; a D band at 1365 + 70 cm ^-1 and a G band at 1589 ± 70 cm ^-1 ; a D band at 1365 ± 50 cm ^-1 and a G band at 1589 ± 50 cm ^-1 ; a D band at 1365 ± 30 cm ^-1 and a G band at 1589 ± 30 cm ^-1 ; or have a D band at 1365 + 20 cm ^-1 and a G band at 1589 + 20 cm ^-1 .

The carbon of the immobilized selenium may include Sp ² carbon-carbon bonds that have Raman peaks including a D band and a G band. A ratio of the area of the D band to the G band can range from 0.01 to 100, from 0.1 to 50, or from 0.2 to 20.

The carbon of the immobilized selenium may include Sp ² carbon-carbon bonds that have Raman peaks including a D band and a G band. Each of the D band and the G band may have a shift to a higher wavenumber ≥ 1 cm ^-1 , ≥ 2 cm ^-1 or more.

The carbon of the immobilized selenium can be doped with one or more other elements of the table of the periodic table.

The carbon of the immobilized selenium can be porous. The pore size distribution of the carbon skeleton can be between one Angstrom and a few micrometers. The pore size distribution may have at least one peak located between one Angstrom and 1000 Angstroms, between one Angstrom and 100 Angstroms, between one Angstrom and 50 Angstroms, between one Angstrom and 30 Angstroms or between one Angstrom and 20 Angstroms. The porosity of the carbon skeleton can have pore size distributions with more than one peak in the above ranges.

The carbon of the immobilized selenium can have a pore volume between 0.01 ml / g and 5 ml / g; between 0.01 ml / g and 3 ml / g; between 0.03 ml / g and 2.5 ml / g; or between 0.05 ml / g and 2.0 ml / g.

The carbon of the immobilized selenium can have a pore volume (which has a pore size <100 Angstroms, <50 Angstroms, <30 Angstroms or <20 Angstroms) that is> 30%,> 40%,> 50%,> 60%,> 70 % or> 80% of the total measurable pore volume.

The carbon of the immobilized selenium can have a surface area> 400 m ² / g,> 500 m ² / g,> 600 m ² / g,> 700 m ² / g,> 800 m ² / g,> 900 m ² / g or > 1000 m ² / g.

The carbon of the immobilized selenium can be amorphous and can have a broad peak centered at a d-spacing around 5.2 angstroms.

The carbon of the immobilized selenium can have any desired morphology, namely platelets, spheres, fibers, needles, tubes, irregular, contiguous, agglomerated, single or any solid particles. Platelet, fiber, needle, tube, or a morphology that has a certain aspect ratio may be beneficial for achieving better contact between particles, resulting in improved electrical conductivity (versus immobilized selenium made from a different aspect ratio), which for an electrochemical cell, such as a rechargeable battery, can be inexpensive.

The carbon of the immobilized selenium can have any particle size, with an average particle size between 1 and 9 nanometers and 2 millimeters, between 1 and 9 nanometers to <1000 micrometers or between 20 nanometers and 100 micrometers.

The selenium of the immobilized selenium can be amorphous, as determined, for example, by X-ray diffraction. The diffraction peak of the selenium of the immobilized selenium, which can have ad-spacing around 5.2 angstroms, can be weaker than the diffraction peak for the carbon skeleton, for example 10% weaker, 20% weaker, 30% weaker or 40% % weaker.

In one example, the method of making the immobilized selenium can include:

(a) physically mixing carbon and selenium. The physical mixing can be done by ball milling (dry or wet), mortar and pestle (dry or wet) mixing, jet milling, horizontal milling, attrition milling, high shear mixing into slurries, conventional slurry mixing with a blade, etc.

(b) The physically mixed carbon and selenium of step (a) can be heated to or above the melting temperature of the selenium. The heating of the mixture of carbon and selenium can be in the presence of an inert gas environment, such as, but not limited to, argon, helium, nitrogen, etc., or in an air or reactive environment.

(c) optionally homogenizing or blending the heated carbon and selenium to achieve selenium immobilization.

(d) cooling the immobilized selenium of step (c) to ambient or room temperature.

In another example, the immobilized selenium can be prepared by dissolving selenium on carbon followed by evaporation. The solvent for dissolving selenium may be an alcohol, an ether, an ester, a ketone, a hydrocarbon, a halogenated hydrocarbon, a nitrogen-containing composite material, a phosphorus-containing composite material, a sulfur-containing composite material, water, and so on.

In another example, the immobilized selenium can be prepared by melting selenium on carbon followed by removing extra or excess non-immobilized selenium.

In one example, the method of making the immobilized selenium can include:

(a) mixing selenium and carbon under dry or wet conditions;

(b) optionally drying the mixture of step (a) at a high temperature;

(c) optionally pelletizing the dried mixture of step (b);

(d) melting the selenium into the carbon to produce the immobilized selenium.

Immobilized selenium can be used as a cathode material for a rechargeable battery. The cathode can contain an inorganic or an organic binder. The inorganic binder can consist of a natural product, such as, for example, CMC, or of a synthetic product, for example, an SBR rubber latex. The cathode can include an optional promoter of electrical conductivity, such as particles derived from graphite, graphene, carbon nanotubes, carbon nanosheets, carbon blacks, etc. Finally, the cathode can include a charge collector, such as an aluminum foil, a copper foil, a carbon foil, a carbon cloth or other metallic foil.

The method of making the cathode may include coating an immobilized selenium-containing slurry on the charge collector, followed by drying the slurry that has been applied to the charge collector (e.g., air drying, oven drying, vacuum oven drying, etc.). The immobilized selenium can be dispersed in the slurry, which can be prepared by a high shear mixer, a conventional mixer, a planetary mixer, a double planetary mixer, a ball mill, a vertical attritor, a horizontal mill, and so on. The sludge can fall on the charge collector followed by drying in air or in vacuum. The coated cathode can then be pressed or roll milled (or calendered) prior to use in a rechargeable battery.

A rechargeable battery can be manufactured by using the immobilized selenium described herein. The rechargeable battery may include a cathode comprising the immobilized selenium, an anode, and a separator that separates the anode and the cathode. The anode, the cathode and the separator can be immersed in an electrolyte such as LiPF ₆ . The anode can be made of lithium, sodium, silicon, graphite, magnesium, tin, etc.

The separator can consist of an organic separator, an inorganic separator or a solid electrolyte separator. The organic separator can comprise a polymer such as polyethylene, polypropylene, polyester, a halogenated polymer, a polyether, a polyketone, etc. The inorganic separator can comprise a glass or quartz fiber or a solid electrolyte separator.

The electrolyte can comprise a lithium salt, a sodium salt or another salt from Group IA, IIA and IIIA in an organic solvent. The organic solvent can consist of an organic carbonate mixture, an ether, an alcohol, an ester, a hydrocarbon, a halogenated hydrocarbon, a lithium-containing solvent, etc.

The rechargeable battery can be used for electronics, an electric or hybrid vehicle, an industrial application, a military application such as a drone, an aerospace application, a marine application, and so on.

The rechargeable battery can have an electrochemical capacity of ≥ 400 mAh / g of active amount of selenium, ≥ 450 mAh / g of active amount of selenium, ≥ 500 mAh / g of active amount of selenium, ≥ 550 mAh / g of active amount of selenium or ≥ 600 mAh / g of active amount of selenium.

The rechargeable battery can experience electrochemical cycling for ≥ 50 cycles, ≥ 75 cycles, ≥ 100 cycles, ≥ 200 cycles, and so on.

The rechargeable battery can be charged and / or discharged at 0.1C, 0.2C, 0.5C, 1C, 1.5C, 2C, 3C, 4C, 5C, 6C, 7C, 8C, 9C, 10C or faster.

The rechargeable battery can have a specific capacity of the battery> 30%,> 40%,> 50%,> 60%,> 70% or> 80% of the 2nd specific discharge capacity at a cycling rate of 0.1C after charging Discharge cycling at a high C rate (for example 5 cycles at 0.1C, 5 cycles at 0.2C, 5 cycles at 0.5C, 5 cycles at 1C, 5 cycles at 2C, 5 cycles at 5C and 5 cycles at 10C).

Wobei η_c die coulombsche Effizienz (%) ist

• Q_out die Menge an Ladung ist, die aus der Batterie während eines Entladezyklus austritt.
• Q_in die Menge an Ladung ist, die in die Batterie während eines Ladezyklus eintritt.

The rechargeable battery can have a Coulomb efficiency of 50%, 60%, 70%, 80% or 90% or even about 100%. The coulomb efficiency of a battery is defined as follows: $${\eta }_c=\frac{Q_{Out}}{Q_{in}}$$

Where η _{c is} the Coulomb efficiency (%)

• Q _{out is} the amount of charge leaked from the battery during a discharge cycle.
• Q _{in is} the amount of charge that enters the battery during a charge cycle.

The rechargeable battery can be charged at a C rate of 0.1C, 0.2C, 0.5C, 1C, 1.5C, 2C, 3C, 4C, 5C, 6C, 7C, 8C, 9C, 10C or faster. A C-rate is a measure of the rate at which a battery is discharged from its maximum capacity. For example, a rate of 1C means that the discharge current will discharge the entire battery in 1 hour. For a battery with a capacity of 100 Ah, for example, this corresponds to a discharge current of 100 A. A rate 5C for the same battery would be 500A, and a rate 0.5C would be 50 A.

The cathode of the rechargeable battery can comprise one or more elements of a chalcogen group, such as selenium, sulfur, tellurium and oxygen.

The anode of the rechargeable battery may include at least one of alkali metal, alkaline earth metals, and Group IIIA metals.

The separator of the rechargeable battery may comprise an organic separator or an inorganic separator.

The electrolyte of the rechargeable battery may include at least one of alkali metals, alkaline earth metals, and Group IIIA metals; and a solvent of the electrolyte may comprise an organic solvent based on carbon, ether, or ester.

The rechargeable battery can have a specific capacity of ≥ 400 mAh / g, ≥ 450 mAh / g, ≥ 500 mAh / g, ≥ 550 mAh / g or ≥ 600 mAh / g.

The rechargeable battery can experience electrochemical cycling for ≥ 50 cycles, ≥ 75 cycles, ≥ 100 cycles, ≥ 200 cycles, and so on.

The rechargeable battery can have a specific capacity of the battery> 30%,> 40%,> 50%,> 60%,> 70% or> 80% of the 2nd specific discharge capacity at a cycling rate of 0.1C after charging High C-rate discharge cycling (5 cycles at 0.1C, 5 cycles at 0.2C, 5 cycles at 0.5C, 5 cycles at 1C, 5 cycles at 2C, 5 cycles at 5C and 5 cycles at 10C) exhibit.

The rechargeable battery can have a Coulomb efficiency of ≥ 50%, ≥ 60%, ≥ 70%, ≥ 80% or ≥ 90%.

A composite material comprising selenium and carbon is disclosed therein, wherein the composite material can have a platelet morphology with an aspect ratio of 1, 2, 5, 10 or 20.

The selenium of the immobilized selenium can be amorphous, for example as determined by X-ray diffraction. The selenium diffraction peak of the immobilized selenium, which may have ad spacing around 5.2 angstroms, may be weaker than that for a carbon skeleton, for example 10% weaker, 20% weaker, 30% weaker, or 40% weaker than that Carbon skeleton.

In one example, the method of making the composite material may include:

(a) physically mixing carbon and selenium. The physical mixing can be done by ball milling (dry or wet), mortar and pestle (dry or wet) mixing, jet milling, horizontal milling, attrition milling, high shear mixing into slurries, conventional slurry mixing with a blade, etc .;

(b) the physically mixed carbon and selenium of step (a) can be heated to the melting temperature of selenium or higher, and the heating can occur in the presence of an inert gas environment such as argon, helium, nitrogen, etc., or in air - or reactive environment; and

(c) the heated carbon and selenium of step (b) can be homogenized or blended as an aid in achieving selenium immobilization.

In another example, the composite material can be prepared by dissolving selenium on carbon followed by evaporation. The solvent for dissolving selenium may include an alcohol, an ether, an ester, a ketone, a hydrocarbon, a halogenated hydrocarbon, a nitrogen-containing composite material, a phosphorus-containing composite material, a sulfur-containing composite material, water, and so on.

The composite material can be prepared by melting the selenium on (or in) the carbon, followed by removal of extra or excess non-immobilized selenium.

In one example, a method of making the composite material may include:

(a) mixing selenium and carbon under dry or wet conditions;

(b) optionally drying the mixture of step (a) at a high temperature;

(c) optionally pelletizing the dried mixture of step (b);

(d) melting the selenium into the carbon to produce the immobilized selenium.

The composite material can be used as a cathode material for a cathode of a rechargeable battery. The cathode can contain an inorganic or an organic binder. The inorganic binder can be a natural product such as CMC, or a synthetic product such as SBR rubber latex. The cathode can include an optional promoter of electrical conductivity, such as small particles derived from graphite, graphene, carbon nanotubes, carbon nanosheets, carbon blacks, etc. Finally, the cathode can include a current charge collector, such as aluminum foil, copper foil, carbon foil, a Carbon fabric or other metallic foil.

The method of making the cathode may involve coating an immobilized selenium-containing slurry on the charge collector followed by drying the slurry that has been applied to the charge collector (e.g., air drying, oven drying, vacuum oven drying, etc.). The immobilized selenium can be dispersed in the slurry, which can be prepared by a high shear mixer, a conventional mixer, a planetary mixer, a double planetary mixer, a ball mill, a vertical attritor, a horizontal mill, and so on. The slurry can be applied to the charge collector followed by drying in room air or in a vacuum. The coated cathode can then be pressed or roll milled (or calendered) prior to use in a rechargeable battery.

A rechargeable battery can be manufactured by using the composite material described above. The rechargeable battery can be charged at 0.1C, 0.2C, 0.5C, 1C, 1.5C, 2C, 3C, 4C, 5C, 6C, 7C, 8C, 9C, 10C or faster.

Example 13: Preparation of the immobilized selenium doped with sulfur, electrode and batteries thereof

In accordance with the concepts and procedures described in Example 10, 5 atomic% (at%) selenium, 20 at% selenium, 35 at% selenium, and 50 at% selenium were immobilized separately by sulfur in the synthesis of the sulfur doped selenium, which is set out in detail in Table 4 below. Samples of the sulfur-doped immobilized selenium were synthesized with the carbon backbone prepared in accordance with the concepts and procedures described in Example 9. Table 4 Sample ID Se, at% S, at% Se, wt% S, wt% Se95S5 95 5 97.9 2.1 Se80S20 80 20th 90.8 9.2 Se65S35 65 35 82.1 17.9 Se50S50 50 50 71.1 28.9

The immobilized sulfur-doped selenium samples thus prepared were then used to connect a number of cathodes 4th comprising immobilized sulfur-doped selenium according to the concepts and procedures described in Example 11 for the immobilized selenium.

The cathodes so prepared, comprising immobilized sulfur-doped selenium, were then used in this example to prepare button cell batteries in accordance with the concepts and procedures described in Example 12.

The assembled coin cell batteries in this example were then tested in the battery tester described in Example 12 following the same test protocols described in Example 12 at 0.1C and 1C charge and discharge cycling rates.

The electrochemical cycling results at 0.1C for button cell batteries containing a cathode composed of the selenium cathode of immobilized sulfur-doped selenium made with an immobilized sulfur-doped selenium sample (Se50S50 in Table 4) are in 18th shown with a 2nd cycle discharge capacity of 821 mAh / g (which is considered good), and a consistent coulombic efficiency ≥ 95%, typically ≥ 98% (which is also considered good) or even 100%.

If selenium is assumed to have a stoichiometric specific capacity of 675 mAh / g at the 0.1C cycling rate, the sulfur specific capacity would be assumed to be around 1,178 mAh / g (which is considered good for sulfur). The Coulomb efficiency of ≥ 95%, ≥ 98% or even 100% indicates that there is no discernible amount of sulfur oscillating between the cathode and anode. Sulfur species in the battery with immobilized sulfur-doped selenium work well in an electrolyte that includes carbonate. Typically, sulfur is not expected to work well in a Li-S battery that has carbonate as an electrolyte; a conventional Li-S battery typically uses an electrolyte based on ether. Carbonate-based electrolyte is typically used in current lithium-ion batteries. Carbonate-based electrolyte is more economical and much more readily available on the market than ether-based electrolyte.

The electrochemical cycling results at the 1C cycling rate for button cell batteries containing a cathode composed of the selenium cathode of immobilized sulfur-doped selenium made with an immobilized sulfur-doped selenium sample (Se50S50 in Table 4) are in 19th shown with a discharge capacity of the 2nd cycle of 724 mAh / g and a consistent coulombic efficiency ≥ 95%, typically ≥ 98% or even 100%.

If selenium is assumed to have a specific capacity of 625 mAh / g at the 1C cycling rate, the sulfur specific capacity would be assumed to be around 966 mAh / g (which is also unexpected). Sulfur is an insulator and has a very low electrical conductivity. Typically, a Li-S battery cannot cycle well at a fast cycling rate such as an IC rate.

As can be seen, when immobilized sulfur-doped selenium is used as a cathode material in a rechargeable battery, it overcomes two fundamental problems associated with Li-S batteries, namely pendulum effect and low cycling rate. When these two problems are solved, a battery including a cathode made of immobilized sulfur-doped selenium can have high energy density and high power density in real applications.

As seen in one example, an immobilized sulfur-doped selenium system or mass can be formed by the process comprising: (a) mixing selenium, carbon and sulfur to form a selenium-carbon-sulfur mixture; (b) heating the mixture of step (a) to a temperature above the melting temperature of selenium; and (c) causing the heated mixture of step (b) to cool to ambient or room temperature, thereby forming the mass of immobilized sulfur-doped selenium.

The bulk of the immobilized sulfur-doped selenium of step (c) can comprise selenium and sulfur in a carbon skeleton.

Step (a) can be done under a dry or a wet condition.

Step (b) can involve homogenizing or blending the mixture.

Step (a) can include forming the selenium-carbon-sulfur mixture in a bulk. Step (b) can include heating the mass to a temperature above the melting temperature of selenium. Step (c) may include causing the mass or allowing the mass to cool to ambient or room temperature.

Step (b) may involve heating the mixture for a time sufficient for selenium and carbon and sulfur to react fully or partially.

In another example, a method of making a system or mass of immobilized sulfur-doped selenium may include: (a) forming a carbon backbone; and (b) melting selenium and sulfur into the carbon framework.

In another example, a method of forming a system or mass of immobilized sulfur-doped selenium may include: (a) mixing selenium and carbon and sulfur; and (b), following step (a), causing selenium and sulfur to dissolve on the carbon, thereby forming the system or mass of immobilized sulfur-doped selenium.

A solvent for dissolving the selenium and the sulfur can be an alcohol, an ether, an ester, a ketone, a hydrocarbon, a halogenated hydrocarbon, a nitrogen-containing composite material, a phosphorus-containing composite material, a sulfur-containing composite material or water. The solvent can be added to one or more of the selenium, sulfur or carbon before step (a), during step (a), or during step (b).

The method may further include (c) removing excess non-immobilized selenium, non-immobilized sulfur, or both from the system or bulk of immobilized sulfur-doped selenium.

There is also disclosed a rechargeable battery comprising: a cathode comprised of immobilized sulfur-doped selenium deposited on an electrically conductive substrate; a separator disposed in direct contact with the electrically conductive substrate and in contact with the immobilized sulfur-doped selenium, and an anode spaced from the cathode by the separator.

The rechargeable battery may further include the anode that is spaced from the separator by lithium. In one example, the lithium can be in the form of a lithium foil.

The rechargeable battery may further include the cathode, the separator, the anode, and the lithium immersed in an electrolyte.

In the rechargeable battery, the immobilized sulfur-doped selenium may comprise a selenium-carbon-sulfur mixture, the selenium and the sulfur having been melted into the carbon skeleton.

In the rechargeable battery, the separator can be formed from an organic material, an inorganic material, or a solid electrolyte.

The rechargeable battery can have a Coulomb efficiency of ≥ 95%.

After describing a method for producing a selenium-carbon composite material, a method for producing immobilized selenium and using the immobilized selenium in, for example, a rechargeable battery, a method for producing immobilized selenium in a porous carbon with the presence of a desirable level will be discussed Oxygen types and the use of immobilized selenium in a rechargeable battery are described.

It should be noted that selenium is one of the chalcogens that includes sulfur, selenium, tellurium, etc. The descriptions relating to selenium in the present disclosure apply equally to the remainder of chalcogen elements such as sulfur and tellurium.

In the present invention, selenium atoms or molecules are oxidized either in their oxidized form as an element (in a charged state in a rechargeable battery) or in their reduced form as selenide (in a discharged state in a rechargeable battery), selenium atoms are within the Positioned pores of a porous carbon, allowing electrochemical reactions of a rechargeable battery to cycle properly during discharge processes and during charging processes. During a discharge process, an elemental selenium atom (neutral, Se) is reduced at the cathode and gains two electrons to form a selenide anion (Se ^2- ), which typically exists as a salt, lithium selenide, Li ₂ Se, and is still attached to the cathode located to be. The chemical energy of the discharge process is effectively converted to electrical energy of the rechargeable battery, with a minimum level of conversion to heat due to the presence of the battery's intrinsic internal electrical resistance. During the charging process of a rechargeable battery, electrical energy is also effectively converted into chemical energy, which is why a selenide anion in Li ₂ Se form on the cathode is oxidized and loses two electrons to form an elemental selenium atom that is still on the cathode . If selenium is not immobilized in a porous carbon, it can An intermediate selenium species (typically in a polyselenide form Sen ^2- ) is formed in a cathode during the electrochemical reduction / oxidation process (ReDox process) and dissolves in a liquid electrolyte of the battery system. The dissolved intermediate polyselenide species is then transported in the liquid electrolyte from the cathode through a battery separator to an anode, where it finds metallic lithium, reacts with the metallic lithium atoms and a salt consisting of lithium and selenium on the surface of the Lithium anode forms. The chemical energy generated from the reactions of lithium and intermediate selenium species on the anode is converted to heat instead of electrical energy, which is highly undesirable. Additionally, selenium salt that is formed on the anode can then be converted back, even partially, to a polyselenide anion, which is then dissolved in the battery's electrolyte and transported back to the cathode, where it consumes additional electrical energy by acquiring electrons and becoming elemental Selenium is converted back. Converting electrochemical energy from selenium to heat, or consuming additional electrical energy, even if the rechargeable battery can be cycled, is undesirable due to undesirably low cycling efficiency. It should be noted that a battery with undesirably low cycling efficiency will often not function properly for a desirable number of cycles.

The present invention thus embodies that selenium immobilization in a porous carbon framework is desirable in order to achieve useful cycling of a rechargeable battery comprising a lithium anode, selenium cathode, a separator and an electrolyte. Selenium is immobilized in a porous carbon and has an activation energy which, in one example, is> 95 kJ / mol,> 98 kJ / mol,> 101 kJ / mol,> 104 kJ / mol,> 107 kJ / mol or> 110 kJ / Mole can be. The interaction of selenium and carbon in the immobilized selenium, which comprises selenium and porous carbon, is often more frequent, in one example has a collision frequency> 2.5 × 10 ⁵ ,> 3.0 × 10 ⁵ ,> 3.5 × 10 ⁵ ,> 4.0 × 10 ⁵ ,> 4.5 × 10 ⁵ ,> 5.0 × 10 ⁵ ,> 5.5 × 10 ⁵ ,> 6.0 × 10 ⁵ or> 8.0 × 10 ⁵ . The kinetic rate constant (at 50 ° C.) for the immobilized selenium, which comprises selenium and porous carbon, is <1 × 10 ^-10 , <5 × 10 ^-11 , <1 × 10 ^-11 , <5 × 10 in one example ^-12 or <5 × 10 ^-13 . The carbon skeleton plays an important role in the proper immobilization of selenium. Carbon that has a certain amount of microporosity (pore size of 20 angstroms or smaller) is desirable to spatially confine selenium within the micropores of the carbon skeleton to achieve selenium immobilization with desirable levels of activation energy, impact frequency, and kinetic rate constants. The presence of certain amounts of mesoporosity (pore size between 20 Angstroms and 500 Angstroms) and / or macroporosity (pore size greater than 500 Angstroms) in the carbon framework is also necessary for the successful transport of lithium ions into the cathode during the battery discharge process and out of the cathode during the battery charging process desirable although it is not critical to the immobilization of selenium. The amount of microporosity, mesoporosity or macroporosity is typically characterized by the amount of pore volume (ml) per unit weight (g) of the carbon framework. High amounts of porosity, including microporosity, mesoporosity and macroporosity, may be required to spatially confine a high level of selenium in the porous carbon. The more the selenium is loaded into the porous carbon structure (per gram), the more chemical energy and electrical energy can be converted into one another during the cycling process of a rechargeable battery.

The amounts of microporosity for the porous carbon for selenium immobilization can be> 0.3 ml / g,> 0.4 ml / g or> 0.5 ml / g. The total amounts of porosity, including microporosity, mesoporosity and macroporosity, are> 0.4 ml / g,> 0.5 ml / g and> 0.6 ml / g. The percentage of microporosity in the total porosity, including microporosity, mesoporosity and microporosity, is between 50% and 99%, 55% and 97% and 60% and 95%.

A short path is preferred for lithium transport between the bulk of the electrolyte and the point where selenium becomes immobilized in the micropores, while the presence of mesoporosity and macroporosity can be important for successful transport of lithium ions in and out in order to make up for selenium that is immobilized in micropores, which allows the electrochemical processes to function properly during the process of discharging and charging a rechargeable battery. One of the particle dimensions of the porous carbon can preferably be small, possibly <5 µm, <2 µm, <1 µm, <0.5 µm or <0.2 µm: the carbon particle can be relatively large, with interconnected thin walls, or can be small with respect to the particle as a whole. The amount of porous carbon can be characterized by a scanning electron microscope, a transmission electron microscope, an optical microscope, a laser scattering particle size analyzer, and so on.

Selenium is immobilized in the micropore space of a porous carbon particle having a porosity including microporosity, mesoporosity and macroporosity. Selenium is strong through Interactions between selenium and carbon skeleton immobilized within the pores of the porous carbon. Porous carbon with a large surface area can have more active sites at which selenium interacts with the carbon skeleton. The porous carbon preferably has a BET surface area> 600 m ² / g,> 800 m ² / g,> 1,000 m ² / g,> 1,200 m ² / g or> 1,400 m ² / g.

Selenium is effectively immobilized in porous carbon through chemical interactions between the selenium species and the surface of the carbon skeleton. The functional groups associated with oxygen in the porous carbon can be the important species that exhibit strong chemical interactions with selenium. Such strong chemical interactions can result in an effective immobilization of the selenium, in an increase in the activation energy, a reduction in the kinetic rate constant and / or an increase in the impact frequency. In order to achieve desirable levels of chemical interactions between carbon skeleton atoms and selenium atoms or molecules, the amounts of oxygen-linked groups or species as interfaces between carbon and selenium in the porous carbon must be significantly high enough that the immobilization of selenium for a rechargeable battery effective, which can function properly in the electrochemical discharge and charge cycling processes. The amounts of oxygen-associated species or oxygen functional group can be characterized by the amounts of oxygen held in the porous carbon analyzed by an oxygen analyzer (such as the LECO oxygen analyzer). The oxygen content of the porous carbon can also be characterized by other instruments that function similarly to LECO instruments, for example temperature-programmed desorption (or thermal gravimetric analysis, Thermal Gravimetric Analysis - TGA) with a gas detector, such as, but not limited to be a mass spec detector, a thermal conductivity detector, etc., with the option of a comprehensive cold trap mechanism.

Porous carbon for selenium immobilization prefers the amounts of oxygen content of> 2%,> 3%,> 5% or more preferably> 7%.

The oxygen types in the porous carbon can be categorized and characterized by temperature-programmed desorption (TPD), typically CO ₂ -generating oxygen types, CO-producing oxygen types, and water-generating oxygen types. When an inert gas such as helium, nitrogen or argon is flowing as a carrier gas, the sample of a porous carbon is heated at a defined heating rate to a temperature that can be as high as 1000 ° C, temperature-program-heated. Oxygen species in the sample of porous carbon are destroyed at different temperatures by forming CO ₂ , CO and / or water, which are eluted by the carrier gas. For the porous carbon that is used for selenium immobilization, the ratio of the amounts of oxygen in connection with CO ₂ formation to the amounts of oxygen in connection with CO formation can be between 0.5 to 0.95, 0.15 to 0.85 or 0 .2 to 0.8; the amount of oxygen in connection with CO ₂ formation can be greater than>2%,>3%,> 5% or more preferably>7%; the amount of oxygen in connection with CO formation can be greater than>2%,>3%,> 5% or more preferably>7%; the amount of oxygen in connection with water formation can be greater than>2%,>3%,> 5% or more preferably> 7%.

In another aspect, the density of oxygen species (micromoles per square meter or µmol / m ² ) of the carbon skeleton can be critical to achieving a sufficient level of chemical interactions between the carbon surface and the selenium atoms, resulting in satisfactory immobilization of selenium for proper cycling a rechargeable battery results. The porous carbon for selenium immobilization prefers amounts of oxygen content of> 0.8 µmol / m ² ,> 1.0 µmol / m ² ,> 1.2 µmol / m ² ,> 1.4 µmol / m ² or more preferably> 1, 6 µmol / m ² ; or the amount of oxygen in connection with CO ₂ formation CO ₂ is> 0.8 µmol / m ² ,> 1.0 µmol / m ² ,> 1.2 µmol / m ² ,> 1.4 µmol / m ² or more preferably > 1.6 µmol / m ² : or the amount of oxygen in connection with CO formation is> 0.8 µmol / m ² ,> 1.0 µmol / m ² ,> 1.2 µmol / m ² ,> 1.4 µmol / m ² or more preferably> 1.6 µmol / m ² ,

The presence of adequate amounts of oxygen species in the carbon framework appears to play critical roles in the oxidative stability of the Se-C composite. Under ambient conditions, the Se-C composite material made of a carbon skeleton with low amounts of oxygen species appears to be easily oxidized under ambient conditions. The fresh material of such Se-C composite materials shows temperature-gravimetric behaviors similar to those for the Se-C composite material with a carbon skeleton having adequate amounts of oxygen species: however, it was found with surprise that Se-C composite materials that are made with low amounts of oxygen species, aged under ambient conditions for about two years and three months, experienced a large exothermic weight loss at temperatures around 200 to 250 ° C with a Show total weight loss on Se-C composite exceeding the amount of selenium loaded on the carbon when freshly made: in another example, the amount of weight loss at these temperatures seems to correlate well with the amount of carbon skeleton in the Se-C -Correlate composite materials: the higher the amounts of carbon skeleton, the greater the exothermic weight loss at temperatures between 200 ° C and 250 ° C: in another example, the oxygen levels increase for aged (27 months) Se-C composite materials that can be produced with a carbon skeleton that has low amounts of oxygen species, up to about 24%: in another example, it is also noted with interest that the density of the aged Se-C composite materials made up of the carbon skeleton, the low amounts of oxygen species is significantly reduced. Without limiting the scope or spirit of the present invention, the exothermic weight loss may be related to the oxidation of the carbon-selenium composite material by the surrounding oxygen species (ambient oxygen and / or moisture under ambient conditions), and / or aided by oxidation of carbon by surrounding oxygen species through elemental selenium, which results in the formation of the oxidized carbon species in each case: the oxidation of the Se-C composite material may occur close to pore openings of the composite material: The newly formed oxidized carbon types close to pore openings can be closed Form porosity: the closed porosity is then inaccessible to the probing molecules of the helium gas during density measurements, which would result in a decrease in density for aged Se-C composite material samples, which would result with a carbon skeleton that has low amounts of oxygen species de. The decomposition products of carbon species oxidized at temperatures between 200 ° C and 250 ° C under an inert carrier gas such as argon or nitrogen can be related to carbon, selenium and / or oxygen, as an example carbon dioxide, carbon monoxide, carbon diselenide, carbon oxiselenide etc. It must also be noted that the free-standing carbon framework is persistent with low levels of oxygen species under ambient conditions. Carbon and / or selenium in the Se-C composite material made with a carbon skeleton having low levels of oxygen species appear to be susceptible to attack by ambient oxygen species along with selenium. Such oxidative instability may well translate into poor electrochemical cycling performance of a Li-Se rechargeable battery; it is possible for the carbon backbone to be slowly oxidized by the elemental selenium and electrochemical cycling environments, just as under ambient conditions. The formation of oxidized carbon types in a Se-C composite material is undesirable. The amount of selenium in the oxidized carbon species may not participate in the electrochemical cycling of a rechargeable battery, resulting in a permanent loss of specific capacity of the rechargeable battery; the carbon scaffold also plays key roles, besides hosting selenium for its immobilization, providing an electrically conductive pathway for (1) delivering electrons from the external circuit to elemental selenium during the discharge process, and (2) recovering electrons from selenium anions (Se ^2- ) to the external circuit during the discharge process. If carbon fractions are oxidized by the elemental selenium that form oxidized carbon species, the electrical resistance of the carbon skeleton can increase significantly so that the electrically conductive pathway for electron delivery and gain is transferred, eventually reaching a level, during each electrochemical cycle that the rechargeable battery no longer functions properly, not to mention the losses of electrical energy and chemical energy in heat, which is in fact undesirable for a rechargeable battery in aspects of (1) low energy efficiency and (2) thermal management.

In contrast, the Se-C composite made with a carbon skeleton having an adequate level of oxygen species shows no change in thermal gravimetric analysis (TGA) behaviors between the fresh sample and the one under ambient conditions for about two and a half Years of age; there is no exothermic weight loss at a temperature around 200 to 250 ° C; the total weight loss of the TGA is similar to the level of selenium loading (by weight) when freshly made; there is no gain in oxygen content and no decrease in density. A Se-C composite material with a carbon skeleton having adequate amounts of oxygen species somehow achieves a level of satisfactory selenium immobilization by applying strong chemical interactions between carbon and selenium with interfacial oxygen species, which increases the oxidation resistance of the Se-C- Composite material improved.

Effective selenium immobilization in a carbon skeleton can be achieved by the presence of adequate amounts of oxygen species in the Se-C composite, possibly as an interface species that allows strong chemical interactions between the carbon skeleton and selenium (in any chemical form). The amounts of desired oxygen species in the immobilized selenium-carbon composite can depend on the level of oxygen species in the carbon skeleton source and the level of selenium loading (by weight) in the Se-C composite. For one Selenium loading of 50% or lower, the amount of oxygen types in the Se-C composite material is> 0.63 mmol / g,> 0.94 mmol / g,> 1.56 mmol / g or> 2.19 mmol /G; for a selenium loading between 50% and 60% (including 60%), the amount of the types of oxygen in the Se-C composite material is> 0.5 mmol / g,> 0.75 mmol / g,> 1.25 mmol / g or> 1.75 mmol / g; for a selenium loading of 60% or more, the amount of oxygen species in the Se-C composite material is> 0.31 mmol / g,> 0.47 mmol / g,> 0.78 mmol / g or> 1.09 mmol / g.

It should be noted that the appropriate amounts of oxygen species in the Se-C composite material are not related to the oxygen species involved in exothermic weight loss at temperatures between 200 ° C and 250 ° C. The oxygen in connection with the exothermic weight loss at temperatures between 200 ° C and 250 ° C can very well result from the post-oxidation of the Se-C composite material under ambient conditions with oxygen types such as oxygen and / or moisture in air.

The amount of oxygen species in the porous carbon is usually generated during a manufacturing process of the porous carbon, which typically includes a carbonization process in which the precursor is converted to carbon, typically at a temperature lower than 700 ° C, more preferably lower than 650 ° C, more preferably less than 600 ° C, followed by an activation process in which the carbon in porous carbon is activated, typically at a temperature greater than 700 ° C, more preferably greater than 750 ° C, perhaps around 800 ° C or above. Porosity amounts of porous carbon depend on the degree of activation. The degree of activation is controlled by the activation temperature and activation time with different activation chemicals, such as water vapor, CO ₂ , a lye (such as NaOH, KOH etc.), a salt (such as K ₂ CO ₃ , Na ₂ CO ₃ , ZnCl ₂ etc.). The stronger the activation conditions, the more porosity is created for the porous carbon. Activation at a higher temperature, such as about 1000 ° C., and / or for a certain period of time results in a porous carbon having a higher level of porosity, which is desirable. Activation at a higher temperature and / or for a longer period of time, however, results in a higher level of oxygen species loss for a porous carbon, which results in a lower level of oxygen species in the porous carbon, which is undesirable. A higher level of oxygen species can be maintained for the porous carbon by its activation at a relatively lower temperature and / or for a shorter period of time, which can result in a lower porosity, which is undesirable. The present disclosure contemplates the spirit of the invention in connection with the peak of both the porosity amounts and the amounts of oxygen species for the porous carbon for selenium immobilization with a desirably high level of loading of selenium with a desirably high level of immobilization, characterized by an increased activation energy, an increased impact frequency or a low level of kinetic rate constant.

As described in the paragraph above, activation at a higher activation temperature and / or for a longer period of time results in a higher level of loss of oxygen species. One of a compromising approach can be activated at a relatively low temperature, such as around 800 ° C or lower, and for a relatively longer period of time, such as, for example, 10 minutes or longer. The present invention also embodies post-treatments for the porous carbon having a desirably high level of porosity that results from a severe activation process that leads to an increase in the amounts of oxygen species in the porous carbon. Such porous carbon reinforced with oxygen species then have desirable levels of both porosity and oxygen species levels as described in the preceding paragraphs.

Porous carbon can be post-treated with an oxidizing agent. The oxidizing agent can be an oxygen-containing chemical. The post-treatment (s) of porous carbon can be carried out in a liquid or in a gas phase. Liquid phase post treatments of the porous carbon can be carried out in an aqueous environment. Liquid phase post-treatments of porous carbon can also be carried out in an organic solvent that is hydrophobic or hydrophilic in nature. Liquid phase post-treatments of porous carbon can be carried out under molten salt conditions.

The post-treatments of porous carbon can be carried out in the liquid at a relatively low temperature, such as the boiling point of the liquid medium or lower. At an elevated pressure that is greater than air pressure, the aftertreatment temperature can be greater than the atmospheric boiling point of the liquid medium. Under vacuum, the post-treatment temperature may have to be lower than the atmospheric boiling point of the liquid medium.

The oxidizing agent may be a nitric acid, hydrogen peroxide, a persulfate salt (as an example, ammonium persulfate, sodium persulfate or potassium persulfate), a manganese, vanadium, chromium salt, or other element related to a transition metal with a high oxidation valence state that allows reduction. The oxidizing agent can be oxygen, ozone, or an organic peroxide.

The post-treatments of the porous carbon in an aqueous environment can be carried out under an acidic condition, a neutral pH condition, or an alkali condition.

The post-treated porous carbon can be washed and dried. The dried, post-treated porous carbon can also be treated at an elevated temperature (for example> 150 ° C.,> 200 ° C. or> 250 ° C.) under a static condition, a gas flow, preferably an inert gas. Such heat treatment can balance the distributions of oxygen species associated with the formation of CO ₂ , oxygen species associated with the formation of CEO, and oxygen species associated with H ₂ O formation.

Post-treatments of porous carbon can improve the amount of oxygen species by> 30%,> 50%,> 100% or> 150%.

It may be more desirable to carry out the selenium immobilization at a temperature that preserves the oxygen species, which can serve as a critical site that enhances the chemical interactions of the selenium and carbon skeleton. The temperature of melting selenium into the pores of porous carbon may be at or above the melting point of selenium. Doping with other elements such as S, Te, or some other impurities can lower the melting point of selenium.

Selenium (with or without a dopant) can be loaded onto the carbon skeleton through an impregnation process. Selenium can be dissolved in a solvent to form a selenium solution. The selenium solution is then impregnated onto a porous carbon, followed by solvent removal by evaporation, which leaves the selenium within the porous carbon. Such an impregnation process can be repeated for the purpose of obtaining useful amounts of selenium charge. This method can also substantially lower the temperature of loading selenium on the porous carbon to a level lower than the melting point of selenium.

The source for generating the porous carbon for selenium immobilization can come from renewable carbon sources, for example, but not limited to, biomass such as sugar, glucose, starch, proteins, soy flour. The source for generating the porous carbon for selenium immobilization can be a salt containing carbon as described in the previous sections. The source for generating the porous carbon for selenium immobilization can be an acid containing carbon such as citric acid, gluconic acid, tannic acid. The carbon source can also be derived from a chemical, for example polyol or a polymer such as polyacrylonitrile or polyphenol.

Description of the carbon production process.

1. (1) Mischen der unterschiedlichen Zutaten: inertes Salz, Aktivierungsmittel und Kohlenstoffvorläufer. Der Mischprozess kann einen Kugelmahlprozess oder einen Gefriertrocknungsprozess einer Lösung der unterschiedlichen Zutaten umfassen; und
2. (2) Karbonisieren des Gemischs und inerte Atmosphäre in hoher Temperatur, dann Waschen mit heißem Wasser, um anorganische Salze zu entfernen, und Trocknen, um ein poröses 3D-Material zu erhalten, das aus untereinander verbundenen gekrümmten dünnen Kohlenstoffschichten besteht.

The carbon material described herein can be obtained by a manufacturing method comprising the following steps:

1. (1) Mixing the different ingredients: inert salt, activating agent and carbon precursor. The mixing process can include a ball milling process or a freeze drying process of a solution of the different ingredients; and
2. (2) Carbonizing the mixture and inert atmosphere in high temperature, then washing with hot water to remove inorganic salts, and drying to obtain a 3D porous material composed of interconnected curved thin carbon layers.

In step (1), the inert salt can be selected from a potassium chloride, sodium chloride or sodium carbonate. The deactivating agent can be selected from potassium carbonate, potassium bicarbonate or potassium oxalate. The carbon precursor can be selected from the renewable carbon sources described above. In step (2), the high temperature carbonization can be carried out at 800 to 900 X, desirably 800 to 850 X: carbonization time 1 to 8 hours, desirably 1 to 4 hours.

The present invention embodies two major processes for making porous carbon from interconnected thin walls that are "self-submitted" and "third-party".

The self-submission process can involve using a salt that contains carbon and can be carbonized, as an example potassium citrate, potassium gluconate, potassium tartrate, potassium citrate, sodium citrate, etc. When the salt is heated it first goes through the melting process that accompanies decomposition, Forms water, carbon dioxide, carbon monoxide, light hydrocarbons, and some tar-like sticky and smelly oils, which can consist of oxygenated hydrocarbons; as the decomposition proceeds, the cation of the original salt may be in a soluble form with an anion of a newly formed carbonate and / or oxalate and / or another form of salt; when the concentration of the newly formed carbonate, bicarbonate, oxalate and / or other anions reaches a saturation point of solubility, the supersaturation conditions of the newly formed carbonate, bicarbonate, oxalate and / or other anions begin to build up as the decomposition process continues; it should be noted that solubility supersaturation of a salt is thermodynamically as good as stable; when a supersaturation point is reached which is no longer (or no longer) kinetically stable, it results in crystallization of the newly formed carbonate, bicarbonate, oxalate salt and / or other anion. An organic carboxylate salt comprising a hydroxyl group (as an example, potassium citrate, potassium gluconate, potassium tartrate, etc.) can be a crystallization inhibitor; such a crystallization inhibitor allows a higher level of supersaturation to develop, which typically results in a large population of crystallites that are small in size. The new crystallized carbonate, bicarbonate salt or in another form can be present in very uniform particle sizes. As decomposition continues, as temperature increases and / or time proceeds, the viscosity of the melt can become higher which can evenly coat the surface of the newly formed carbonate, bicarbonate, oxalate salts and / or other forms of salts. Then carbon finally solidifies on the surfaces of the newly formed crystallites. This carbon submission process is described in this disclosure as a self submission process, a carbonization process. The temperature of the self-submission process can be below 700 ° C. Such a self-submission process can be carried out by ramping up the temperature at a constant rate or at a varied rate. The self-submission process can also be carried out by keeping the heating temperature constant or soaking at a temperature of less than 700 ° C or below.

As the temperature rises, the newly formed, self-template three-dimensional carbon from interconnected thin walls undergoes an activation process by the newly formed crystallites as an activation chemical. As an example, the activation process may be based essentially on the high temperature redox reaction between carbon and newly formed crystallites, such as K ₂ CO ₃ + C → K ₂ O + 2CO, which occurs at about 700 ° C or above. The consumption of carbon can result in the creation of porosity (particularly microporosity) in carbon, resulting in the formation of a three-dimensional porous carbon with interconnected thin walls. The activation temperature can be up to 1100 ° C. The ramp-like speed can be less than 1 ° C / min. up to 100 ° C / min. pass. A flow of an inert carrier gas, for example nitrogen or argon, can be used for the porous carbon manufacturing process. A reactive gas, such as CO ₂ and steam, can also be used separately or together for and during the activation.

An additional or secondary reaction can occur that can contribute to creating the porosity of the carbon. Some of these reaction processes may include: i) the gasification of carbon by CO ₂ generated during the carbonization and / or activation process, ii) the reduction of metal oxides by carbon (as an example K ₂ O + C → CO + 2 K ), iii) the incorporation of certain newly formed metallic species (as an example K) in carbon layers, or iv) a catalytic effect associated with the cations, which is particularly relevant in the case of potassium. In particular, the gasification of the carbon is relevant (C + CO ₂ = 2 CO) as a result of the CO ₂ generated during the decomposition of the K ₂ CO ₃ (K ₂ CO ₃ → K ₂ O + CO ₂ ) that did not react which occurs slowly at a temperature above 800 to 850 ° C.

A foreign template process can involve the use of foreign particles, for example a deactivating agent (for example an alkali metal salt and carbonate such as K ₂ CO ₃ , an alkali metal hydroxide such as KOH), optionally together with an inert salt (for example KCl, NaCl etc.) to produce abundant amounts of porosity from a carbon source. The foreign particles can be mixed with the carbon source before the carbonization or after the carbonization, more preferably before the carbonization step. Such mixing of foreign particles and the carbon source can be accomplished by physical mixing, optionally followed by mechanical milling, or by recrystallization of the carbon source along with the chemical of the foreign particle can be obtained from an aqueous solution, an aqueous slurry or counterparts using an organic liquid medium. The drying process for the recrystallization process can be carried out by evaporation, air drying, oven drying, spray drying or freeze drying.

When the mixture is heated in the foreign template process, the carbonization activation of the carbon source takes place over a salt template particle, similar to what was described in the previous paragraphs about a self-template process. During the carbonation process, the carbon source can somehow melt and decompose as the temperature rises and time goes on, forming byproducts such as CO ₂ , CO, water, light hydrocarbons and some sticky and viscous heavy hydrocarbons. The melt viscosity may increase and the melt may eventually coat and solidify the surface of the foreign particles, forming an interconnected thin walled carbon coating on the surface of the foreign particles. As the temperature continues to rise, the activation process begins and creates porosity, which is essentially due to the high temperature redox reaction, for example K ₂ CO ₃ + C → K ₂ O + 2CO, which occurs at a temperature around 700 ° C or above, can be based.

As an example, when the foreign particles optionally comprise an inert salt, as another example KCl, the melting point of an activation chemical such as K ₂ CO _{3 is} lowered from 891 ° C to, as another example, about 630 ° C. Due to the formation of a KCl-K ₂ CO ₃ liquid phase system at a temperature of around 630 ° C or similar, the activation of the carbon with interconnected thin walls can be significantly accelerated, possibly due to the improved reactivity of K ₂ CO ₃ with the carbonized products (Carbon with interconnected thin walls), possibly due to closer contacts between the activation chemical (such as, in this case, K ₂ CO ₃ ) and the surface of the carbon with interconnected thin walls. This may suggest that the foreign template process with foreign particles comprising an activation chemical and, optionally, an inert salt, is indeed a viable residual strategy for achieving the synthesis of a three-dimensional porous carbon with interconnected thin walls in sufficient quantities May be porosity while maintaining appropriate levels of oxygenated species (activation under less severe conditions, i.e. at a lower activation temperature). At the same time, the surface of the carbon surface can be isolated by the molten KCl-K ₂ CO ₃ liquid phase, which prevents the secondary reaction of the formed CO ₂ and that of the formed porous carbon with interconnected thin walls, possibly by restricting the diffusion of the gaseous CO formed ₂ molecules to the surface of the solidified three-dimensional porous carbon with interconnected thin walls, which is desirable for achieving a higher yield of the porous carbon with interconnected thin walls. In addition, the “monolithic” molten KCl-K ₂ CO ₃ liquid phase can also restrict the gaseous diffusion of the gases emitted, such as volatile carbon, which in one possibility of their redeposition on the three-dimensional porous carbon with interconnected thin walls and an increase in the Yield of the porous carbon with interconnected thin walls can result, which is desirable.

Example 14. Three-dimensional porous carbon with interconnected thin walls: Nanomaterial: carbon production and characterizations - by an external template process: freeze-drying of the aqueous mixture of carbon source such as glucose, activation chemicals such as K ₂ CO ₃ , and, optionally, an inert salt such as KCl.

After dissolving appropriate amounts of KCl, K ₂ CO ₃ and glucose in deionized water, the solution was frozen with liquid nitrogen (-196 ° C), then transferred to a freeze dryer and kept at a temperature of -50 ° C and a pressure of 0.06 mbar freeze-dried, which resulted in a solid mixture of KCI, K ₂ CO ₃ and glucose. Then the solid mixture was carbonized at 850 ° C for 1 hour under an inert atmosphere and cooled to room temperature, followed by washing with hot deionized water, filtering and drying, resulting in a three-dimensional porous carbon material with interconnected thin walls, which is in 20th shown resulted.

The surface of this three-dimensional porous carbon nanomaterial with interconnected thin walls, which was derived from glucose, measured 2,316 m ² / g with a total pore volume of 1.04 cm3 / g and a micropore volume of 0.90 cm3 / g about 86% of the pores described as microporosity and about 14% of pores described as meso- and macroporosity. The N ₂ adsorption isotherm and the pore size distributions of the three-dimensional porous carbon nanomaterial with interconnected thin walls are in 21st shown.

In another example, soy flour is used in place of glucose. Out 22nd It can be seen that the macroscopic structure of the three-dimensional porous carbon nanomaterial with interconnected thin walls derived from soy flour is similar to that derived from glucose. However, this material has a surface area of 2,613 m ² / g, a pore volume of 1.42 cm3 / g and a micropore volume of 1.0 cm3 / g, with about 70% of the pores being described as microporosity and about 30% of the pores, which are described as meso- and macroporosity. The N ₂ adsorption isotherm and pore size distributions of this material are in 23 The amount of mesoporosity of this material derived from soy flour is greater than that for that derived from glucose. Table 5 carbon precursor Activation / Submission Agent Precursor / KCL / K ₂ CO ₃ mass ratio ratio Carbonization temperature (° C) SM-K-800 Soy flour KCl 1 / 6.7 / 0 800 SM-CK-800 K ₂ CO ₃ 1/0/1 800 SM-800 KCl + K ₂ CO ₃ 1/6, 7/1 800 SM-850 KCl + K ₂ CO ₃ 1 / 6.7 / 1 850 GK-800 glucose KCl 1 / 6.7 / 1 800 G-CK-800 K ₂ CO ₃ 1/0/1 800 G-800 KCl + K ₂ CO ₃ 1 / 6.7 / 1 800 G-850 KCl + K ₂ CO ₃ 1 / 6.7 / 1 850 carbon Texture properties SBET (m ² g ^-1 ) V _p (cm ³ g ^-1 ) V _micro (cm ³ g ^-1 ) SM-K-800 470 0.38 0.16 SM-CK-800 2650 1.22 1.04 SM-800 2580 1.19 0.98 SM-850 2613 1.42 1.00 GK-800 335 0.16 0.12 G-CK-800 1443 0.58 0.53 G-800 2000 0.81 0.71 G-850 2316 1.04 0.90 carbon Chemical composition (% by weight) C. O N SM-K-800 75.4 15.7 7.8 SM-CK-800 91.0 7.9 0.73 SM-800 93.6 5.6 0.46 SM-850 93.7 5.6 0.36 GK-800 G-CK-800 G-800 92.7 6.8 0.14 G-850 93.6 5.9 0.19

Table 5 above shows a number of different examples of the three-dimensional porous carbon nanomaterial with interconnected thin walls made by foreign template for different combinations of precursors, activation / template agents; Precursor / activation / template agent mass ratio; and carbonation ratio - result in those shown different combinations of texture properties and chemical composition, where V _BET = apparent surface; Vp = total pore volume; and Vmicro = micropore volume.

Example: Three-dimensional porous carbon nanomaterial with interconnected thin walls. Manufacture of the capacitor and services

The three-dimensional porous carbon nanomaterials with interconnected thin walls in Example 14 can be used as electrodes in electrochemical capacitors. The electrode comprises an organic binder, which can be, for example, PTFE or PVDF. As an option, the electrode also includes an electrical conductivity promoter such as carbon black, graphene, nanotubes, etc. In a typical example, a mixture of 85 wt% active material, 10 wt% binder, and 5% promoter becomes electrical Conductivity prepared.

The manufacturing process for the electrodes may involve preparing a slurry of the various components or their dry mixture in a mortar. The slurry can be applied to a current collector or can be formed into self-supporting electrodes such as disc electrodes. The electrodes can then be pressed or rolled in an electrochemical capacitor prior to use.

A symmetrical electrochemical capacitor can be assembled using the electrodes described above. Two electrodes of the same mass and strength can be used. The current collectors can be made of gold, stainless steel, aluminum, nickel, etc. depending on the electrolyte used.

The electrolyte can be an aqueous acid solution such as sulfuric or chloric acid, a basic solution such as sodium hydroxide or potassium hydroxide, a salt such as lithium sulfate, sodium sulfate, potassium sulfate, etc .; the electrolyte may be an organic solution such as an organic salt such as tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, etc .; or an organic solution, such as an ionic liquid such as 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1- Butyl 3-methylimidazolium tetrafluoroborate, 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, etc., or a pure ionic liquid as mentioned above.

The electrochemical capacitor can be charged at 0.2 A / g, 0.5 A / g, 1 A / g, 5 A / g, 10 A / g, 20 A / g, 50 A / g or faster. The assembled electrochemical capacitors were tested using a computer controlled potentiostat. The tests consisted of cyclic voltammetry (CV) experiments, electrochemical impedance spectroscopy studies (EIS) and galvanostatic charge / discharge cycling tests (CD cycling tests). The cell voltage can be up to 1 V in an acidic or a basic solution, up to 1.5 in an aqueous salt solution and up to 3 V in an organic and ionic liquid electrolyte solution.

in one example, a solution of 1 MH ₂ SO _{4 is used} as the electrolyte. The electrochemical capacitor made with glucose-derived 3-dimensional porous carbon nanomaterial with interconnected thin walls (called glucose-based) has a cell capacity of 57 F / g at 0.2 A / g, and the electrochemical capacitor, made with three-dimensional porous carbon nanomaterial with interconnected thin walls based on soy flour (also called soy flour based) has a capacity of 60 F / g. At an ultra-high current density of 110 A / g, the cell capacity is 24 and 31 F / g, respectively.

In another example, a solution of 1 M Li ₂ SO _{4 is used} as the electrolyte. The glucose-based electrochemical capacitor has a cell capacity of 37 F / g at 0.2 A / g and the soy flour-based electrochemical capacitor of 39 F / g. At a current density of 20 A / g, the cell capacity is 25 and 29 F / g, respectively.

In another example, a solution of EMImTFSI in acetonitrile (1: 1 wt%) was used as an electrolyte. The glucose-based electrochemical capacitor has a cell capacity of 36 F / g at 0.2 A / g, and the soy flour-based electrochemical capacitor of 39 F / g. At a current density of 30 A / g, the cell capacity is 28 and 30 F / g, respectively.

A Ragone-like contact of the electrochemical capacitors with different electrolytes is shown in FIG. X8. The robustness of the electrochemical capacitors was tested by long-term cycling at 5 to 10 A / g for more than 5000 cycles.

Example 16 Three-dimensional porous carbon nanomaterial with interconnected thin walls: carbon production by an external template process, mixing (optionally followed by grinding) the carbon source, such as sugar, glucose, soy flour or sawdust, activation chemicals such as K ₂ CO ₃ and, optionally , an inert salt like KCl.

Appropriate amounts of a carbon source such as sugar, glucose, soy flour, sawdust (e.g., pine sawdust, cherry sawdust, or oak sawdust), an activation chemical such as K ₂ CO ₃ , and, optionally, an inert salt such as KCl, were weighed into an include, followed by physical mixing, which may involve mechanical grinding, followed by transferring to a crucible, which may be made of ceramic, steel, stainless steel, and so on. Under an inert gas flow (which is also optional) the mixture is ramped at a rate of less than 100 ° C / min. heated, optionally to a soak temperature equal to or less than 700 ° C during a period for carbonization, or directly to an activation temperature which is equal to or greater than 700 ° C, and dwell at the temperature for a period of time for the activation. During the ramp-like process, the carbon source goes through a carbonization process by decomposing into CO, CO ₂ , water, light hydrocarbons, and heavy and viscous oily hydrocarbons. During the activation process, CO, CO ₂ , water and volatile carbon materials can continue to form.

After activation, the mixture is mixed with water and optionally neutralized with an acid such as hydrochloric acid, sulfuric acid, nitric acid, etc. The carbon sludge is then filtered and washed with water to a level that has a low level of electrical conductivity, as an example less than 5000 µS / cm, less than 3000 µS / cm, less than 1000 µS / cm and, optionally , with fully demineralized or distilled water, to a conductivity of less than 300 µS / cm, less than 100 µS / cm or even less than 50 µS / cm. The filtered cakes can be dried in an oven to dry out the water.

The resulting three-dimensional porous carbon nanomaterials with interconnected thin walls were characterized with oxygen content, SEM, XRD, Raman, TGA-DSC, N ₂ and CO ₂ BET surface and pore size distributions.

The following table 6 shows an elemental analysis of the 3-dimensional porous carbon nanomaterials with interconnected thin walls, such as 237-8 (self-supplied carbon synthesized from potassium citrate), 237-51A (self-supplied carbon from potassium citrate), SKK2 (externally supplied carbon ) vs. commercial carbon such as Elite C, available from Calgon Carbon of Pittsburgh, Pennsylvania, USA; YP-50 available from Kruray Co. Ltd of Osaka, Japan; Ketjen-Carbon Black, available from Lion Specialty Chemicals Co. Ltd. in Tokyo, Japan; Maxsorb, available from Kansai Coke and Chemicals Co. Ltd. in Hyogo, Japan. Table 6 Sample ID ELEMENTAL ANALYSIS (% by weight) C. O H N S. ELITE C 97.54 1.19 0.45 1.05 0.08 YP-50F 97.96 1.46 0.60 1.08 0.02 KETJEN 98.56 0.33 0.28 0.97 0.10 MAXSORB 96.99 1.33 0.28 1.36 0.01 237-8 87.62 9.29 0.57 1.24 0.01 237-51A 87.84 9.90 0.40 1.12 0.02 SKK2 94.30 5.25 0.31 0.14 - 237-101D 12%

The table above shows two carbon groups, one group being the 3-dimensional porous carbon nanomaterials with interconnected thin walls, such as 237-8 (self-supply carbon, synthesized from potassium citrate), 237-51A (external supply carbon from glucose) , 237-101D (self-original carbon synthesized from potassium citrate) and SKK2 (external original carbon from sugar), which have an oxygen content greater than 1.5% by weight, greater than 2.0% by weight, greater than 3% by weight. -% or greater than 4.0% by weight. XRD studies show that the carbon materials in the table above are all amorphous. Raman studies show that the carbon materials in the table above are also amorphous in nature by showing amorphous carbon signature Raman scattering at both the D-peak and the G-peak.

The prepared porous carbon with interconnected thin walls is then used to prepare selenium immobilization. Appropriate amounts of selenium and carbon are mixed as described above, followed by melting the selenium into the porous carbon with interconnected thin walls in the presence of high levels of oxygen species, resulting in the immobilized selenium of the present invention; reference being made to the above description for the manufacturing process of immobilized selenium in the present disclosure. The immobilized selenium is then characterized by oxygen content analysis, XRD, Raman, SEM, TGA-DSC, etc.

Table of oxygen content analysis of the immobilized selenium in the 3-dimensional porous carbon nanomaterials with interconnected thin walls that are greater than 1.5% by weight, greater than 2.0% by weight, greater than 3% by weight , or greater than 4.0% by weight, vs. the immobilized carbon-selenium composite material prepared with commercially available carbon having an oxygen content of less than 1.5%, less than 2.0% by weight, less than 3% by weight, less than 4.0% by weight. Table 7 Carbon ID C-Se ID O (%) Elite C 115 24 Maxsorb MSP20X 259 14th Ketjen 600JD 352 0.47 237-8 301 2.6 237-51A 366 3.1 237-67 426 4.9 237-101D 483 4.8 SKK-2 385 4.8

Table 7 above shows two different groups of immobilized selenium, a group (called group I, namely Ketjen 600JD, 237-8, 237-51A, 237-67, 237-101D and SKK-2) that has an oxygen content that about one half of the oxygen content for the 3-dimensional porous carbon nanomaterials with interconnected thin walls is from 1% to 10%, from 1.5% to 9% or from 2% to 8%, another group (called group II namely Elite C and Maxsorb MSP20X), which has an oxygen content that is at least five times the oxygen content of carbon, or greater than 8%, greater than 9% or greater than 10%. It should be noted that Ketjun carbon is non-porous carbon, the carbon-selenium composite of which is considered to be non-immobilized selenium, so its oxygen content remains very low, less than 1%.

The oxygen species in Group I immobilized selenium can play critical roles as chemical interfacial groups in the immobilization of selenium, which allows strong interactions between carbon and selenium, resulting in a closer packing of the selenium atoms or species within the pores of the three-dimensional porous carbon nanomaterials interconnected thin walls result, which can translate into an improved impact frequency shown in examples of the present disclosure. Such interactions between the carbon structure and selenium atoms or chemical selenium types can also be reflected in a higher intrinsic density.

As an example, a sample of immobilized selenium made from three-dimensional porous carbon nanomaterials with interconnected thin walls, for example Self-template carbon synthesized from potassium citrate, with a 50-50 ratio (by weight) of the carbon to the selenium. Surprisingly, it was found that its density is 3.42 g / cm3. It should be noted that selenium has a density of 4.819 g / cm3. Using 4.819 g / cm3, the carbon density in the composite material of immobilized selenium is calculated to be about 2.8 g / cm3. It should also be noted that diamond has a density of 3.5 g / cm3; Graphite has a density of about 2.3 g / cm3; and amorphous carbon has a typical density of about 2.0 g / cm3.

The immobilized selenium is then used to prepare a cathode of a rechargeable battery by mixing appropriate amounts of immobilized selenium, an aqueous or organic medium and at least one binder as described above, followed by coating on a charge collector, as an example aluminum foil, what results in a cathode comprising immobilized selenium. For the manufacturing process of a cathode which comprises immobilized selenium, one should use the above description in the present disclosure.

The resulting cathode, comprising immobilized selenium, is then used to assemble a rechargeable battery with an anode, as an example lithium, a separator and an electrolyte. For the assembly process of a rechargeable battery that includes a cathode that includes immobilized selenium, refer to the description above in the present disclosure.

The resulting carbon sample can also be used in an electrode manufacturing process for a capacitor of a rechargeable battery.

The examples have been described with reference to the accompanying figures. Changes and modifications may arise for other people when reading and understanding the above examples. The above examples should therefore not be construed as limiting the disclosure.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

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Claims (11)

A method of making a mass of immobilized selenium comprising: (a) forming a mixture of selenium, carbon and oxygen; (b) heating the mixture of step (a) to a temperature above the melting temperature of the selenium; and (c) causing the heated mixture of step (b) to cool to ambient or room temperature, thereby forming the mass of immobilized selenium. Procedure according to Claim 1 wherein the carbon is self-original carbon or foreign-original carbon. Procedure according to Claim 1 wherein for the selenium loading in the carbon of ≤ 50%, the amount of oxygen in the mixture is ≥ 0.63 millimoles / gram. Procedure according to Claim 1 , where for the selenium loading in the carbon between 50% (exclusive) and 60% (including) (that is to say 50% <selenium loading ≤ 60%) the amount of oxygen in the mixture is ≥ 0.5 millimoles / gram. Procedure according to Claim 1 , wherein for the selenium loading in the carbon, the amount of oxygen in the mixture is ≥ 60% ≥ 0.31 millimoles / gram. Procedure according to Claim 1 further including activating the carbon prior to step (a), thereby forming pores in the carbon. Procedure according to Claim 5 which further includes combining or mixing the activated carbon with an oxidizing agent. Procedure according to Claim 7 wherein the oxidizing agent comprises at least one of the following: nitric acid; Hydrogen peroxide; organic peroxide; Oxygen; and / or ozone. Procedure according to Claim 7 wherein the oxidizing agent comprises at least one of the following in an aqueous environment: ammonium persulfate; Sodium persulfate; Potassium persulfate; a manganese salt; a vanadium salt, and / or a chromium salt. Procedure according to Claim 1 wherein the self-original carbon is made by a process that includes: carbonizing a salt by melting until supersaturation of anions in the melt forms a crystallized salt in the melt; Increasing the viscosity of the melt until the melt coats surfaces of crystallites of the crystallized salt; and solidifying the carbon in the melt on the surfaces of the crystallites. A mass of immobilized selenium comprising a mixture of: Selenium; Carbon; and Oxygen.

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