Anode active material with a buffering zone

Abstract

Improved anodes and cells are provided, which enable fast charging rates with enhanced safety due to much reduced probability of metallization of lithium on the anode, preventing dendrite growth and related risks of fire or explosion. Anodes and/or electrolytes have buffering zones for partly reducing and gradually introducing lithium ions into the anode for lithiation, to prevent lithium ion accumulation at the anode electrolyte interface and consequent metallization and dendrite growth. Various anode active materials and combinations, modifications through nanoparticles and a range of coatings which implement the improved anodes are provided.

1 . An anode comprising anode active material particles, wherein the anode active material particles have, at a surface thereof, a buffering zone configured to receive lithium ions from an interface of the anode active material particles with an electrolyte, partly mask a positive charge of the received lithium ions, and enable the partly masked lithium ions to move into an inner zone of the anode active material particles for lithiation therein, wherein the interface of the anode active material particles with the electrolyte comprises an ionic liquid additive comprising anions and cations, wherein the anions are larger than lithium ions, and wherein a size and concentration of the anions in the buffering zone provides a mobility gradient of lithium ions in the buffering zone. 
     
     
         2 . An anode according to  claim 1 , wherein the anode active material particles comprise metalloid cores and composite coatings, wherein the metalloid cores comprise at least one of Si, Ge and Sn and are between 20-500 nm in diameter. 
     
     
         3 . The anode of  claim 1 , wherein the buffering zone contains anions providing electron donating groups and cations providing non-electron donating groups, wherein the anions are more mobile than the cations in the buffering zone. 
     
     
         4 . The anode according to  claim 1 , wherein the anode active material particles have a coating comprising bonding molecules which bind to the anions and/or cations in the ionic liquid. 
     
     
         5 . The anode of  claim 1 , wherein the buffering zone is further configured to provide a mobility gradient for anions in the buffering zone. 
     
     
         6 . A lithium ion cell comprising the anode of  claim 1 . 
     
     
         7 . A method of configuring an anode, comprising providing anode active material particles, at a surface thereof, with a buffering zone configured to receive lithium ions from an interface of the anode active material particles with an electrolyte, partially mask a positive charge of the received lithium ions, and enable the partially masked lithium ions to move into an inner zone of the anode active material particles for lithiation therein, comprising wherein the interface of the anode active material particles with the electrolyte comprises an ionic liquid additive comprising anions and cations, wherein the anions are larger than lithium ions, and wherein a size and concentration of the anions in the buffering zone provides a mobility gradient of lithium ions in the buffering zone. 
     
     
         8 . The method according to  claim 7 , comprising providing the anode active material particles with metalloid cores and composite coatings, wherein the metalloid cores comprise at least one of Si, Ge and Sn and are between 20-500 nm in diameter. 
     
     
         9 . The method according to  claim 7 , wherein the buffering zone contains anions providing electron donating groups and cations providing non-electron donating groups, wherein the anions are more mobile than the cations in the buffering zone. 
     
     
         10 . The method according to  claim 7 , comprising providing the anode active material particles with a coating having bonding molecules which bind to the anions and/or cations in the ionic liquid. 
     
     
         11 . The method according to  claim 7 , comprising configuring the buffering zone to provide a mobility gradient for anions in the buffering zone. 
     
     
         12 . The method according to  claim 7 , comprising charging the anode in a lithium ion cell.