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

Abstract

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

1 . A method of continuously forming amorphous active material structures for electrochemical cells, the method comprising:
 introducing an electroplating liquid solution into an electroplating bath, wherein:
 the electroplating bath comprises a working electrode and a counter electrode submerged into the electroplating liquid solution, 
 the electroplating liquid solution comprises one or more precursors, one or more salts, one or more solvents, and one or more surfactants dissolved in the electroplating liquid solution, and 
 one or more precursors comprising one or more elements selected from the group consisting of silicon (Si), tin (Sn), and germanium (Ge); and 
   applying an electrical potential between the working electrode and the counter electrode and through the electroplating liquid solution, wherein:
 applying an electrical potential causes the amorphous active material structures to form from the one or more precursors in the electroplating bath, and 
 the amorphous active material structures comprise one or more elements selected from the group consisting of silicon (Si), tin (Sn), and germanium (Ge). 
   
     
     
         2 . The method of  claim 1 , wherein the one or more surfactants comprise chlorine species selected from the group consisting of elemental chlorine and chlorine gas. 
     
     
         3 . The method of  claim 2 , wherein the chlorine species have a concentration of 10 ppm to 100,000 ppm in the electroplating liquid solution. 
     
     
         4 . The method of  claim 2 , wherein:
 the electroplating bath comprises a porous membrane,   the porous membrane is permeable to the chlorine species, and   the porous membrane separates the working electrode and the counter electrode.   
     
     
         5 . The method of  claim 2 , wherein the amorphous active material structures further comprise chlorine (Cl). 
     
     
         6 . The method of  claim 1 , wherein the one or more surfactants comprise cations selected from the group consisting of BMP + , N 4444   + , and PMP + . 
     
     
         7 . The method of  claim 1 , wherein the one or more surfactants comprise at least one halide selected from the group consisting of tetrabutylammonium chloride (Bu 4 NCl), tetrabutylammonium bromide (Bu 4 NBr), tetrapropylammonium chloride (Py 4 NCl), tetraethylammonium chloride (Et 4 NCl), lithium chloride (LiCl), 1-Butyl-1-methylpyrrolidinium chloride (PYR 14 Cl), and 1-Propyl-1-methylpyrrolidinium chloride (PYR 13 Cl). 
     
     
         8 . The method of  claim 1 , wherein the amorphous active material structures further comprise one or more elements selected from the group consisting of carbon and oxygen. 
     
     
         9 . The method of  claim 1 , wherein the one or more solvents of the electroplating liquid solution comprise at least one selected from the group consisting of tetraglyme, triglyme, diglyme, monoglyme, tetrahydrofuran, propylene carbonate (PC), and dimethyl carbonate (DMC). 
     
     
         10 . The method of  claim 1 , wherein the electroplating liquid solution comprises an ionic liquid comprising one or more anions selected from the group consisting of AlCl 4   − , BF 4   − , SiCl 5   − , PF 6   − , FSI − , TFSI − , and Br 3   − . 
     
     
         11 . The method of  claim 1 , wherein the one or more precursors of the electroplating liquid solution are selected from the group consisting of trichlorosilane (SiHCl 3 ), silicon tetrachloride (SiCl 4 ), silicon tetrabromide (SiBr 4 ), silicon tetraiodide (SiI 4 ), germanium halides, and metal salts. 
     
     
         12 . The method of  claim 1 , wherein the one or more salts of the electroplating liquid solution are selected from the group consisting of tetrabutylammonium chloride (Bu 4 NCl), tetrapropylammonium chloride (Py 4 NCl), tetraethylammonium chloride (Et 4 NCl), lithium chloride (LiCl), 1-Butyl-1-methylpyrrolidinium chloride (PYR 14 Cl ), and 1-Propyl-1-methylpyrrolidinium chloride (PYR 13 Cl). 
     
     
         13 . The method of  claim 1 , wherein the counter electrode comprises a carbon structure. 
     
     
         14 . The method of  claim 1 , wherein the working electrode comprises or is formed from one or more materials selected from the group consisting of titanium (Ti), platinum (Pt), nickel (Ni), copper (Cu), stainless steel, silicon (Si) wafers, and glassy carbon (glassy-C). 
     
     
         15 . The method of  claim 1 , wherein the electroplating liquid solution is maintained at a temperature of less than 200° C. 
     
     
         16 . The method of  claim 1 , wherein the electroplating liquid solution comprises one or more anions selected from the group consisting of AlCl 4   − , SiCl 5   − , and Br 3   − . 
     
     
         17 . The method of  claim 1 , wherein the electroplating liquid solution comprises cations having an ionic radius greater than 0.1 nanometers. 
     
     
         18 . The method of  claim 1 , wherein the amorphous active material structures have a porosity of at least 20%. 
     
     
         19 . The method of  claim 1 , wherein the amorphous active material structures are loose particles with a size from 1 nanometer to 100 micrometers. 
     
     
         20 . The method of  claim 1 , wherein the amorphous active material structures are formed by deposition on the working electrode.