Battery control systems

Abstract

Various embodiments herein relate to the design of battery stacks, batteries and battery packs that are able to accommodate volumetric expansion in the battery materials. These designs may be especially useful in connection with batteries having negative electrodes made of lithium metal and/or positive electrodes made of an electrochemically active conversion material. These batteries may expand on the order of 10-40% during cycling. The battery designs disclosed herein include compressible regions that span a wide variety of different designs and implementations.

What is claimed is: 
     
         1 . A battery comprising:
 (a) a plurality of unit cells arranged as one or more rechargeable battery stacks, each unit cell comprising:
 (i) a positive electrode layer; 
 (ii) a lithium metal negative electrode layer; 
 (iii) an electrolyte layer positioned between the positive electrode layer and the negative electrode layer; 
 (iv) a positive current collector layer in electrical contact with the positive electrode layer; and 
 (v) a negative current collector layer in electrical contact with the negative electrode layer; 
   (b) one or more compressible structures configured to apply pressure to the battery stacks during expansion of the one or more battery stacks during charge; and   (c) a confinement structure about the one or more stacks and the one or more compressible structures.   
     
     
         2 . The battery of  claim 1 , wherein the one or more compressible structures, taken together, accommodate at least about 10% volumetric expansion in the one or more battery stacks during charge. 
     
     
         3 . The battery of  claim 1 , wherein the one or more compressible structures comprise a single compressible structure positioned proximate the one or more battery stacks, and wherein the confinement structure is a battery can. 
     
     
         4 . The battery of  claim 1 , wherein the one or more compressible structures are positioned between at least two of the battery stacks, and wherein the confinement structure is a battery can. 
     
     
         5 . The battery of  claim 1 , wherein the one or more compressible structures are positioned between adjacent unit cells of the stack. 
     
     
         6 . The battery of  claim 5 , wherein the one or more compressible structures are positioned between layers of positive current collectors and/or between layers of negative current collectors of adjacent unit cells of the stack. 
     
     
         7 . The battery of  claim 1 , wherein at least one of the positive or negative current collector layers is also one of the compressible structures. 
     
     
         8 . The battery of  claim 7 , wherein the compressible structure that is one of the positive or negative current collector layers is selected from the group consisting of a carbon nanofoam, an aerogel, and non-woven carbon fiber. 
     
     
         9 . The battery of  claim 1 , wherein the one or more rechargeable battery stacks and the one or more compressible structures have a compressible/cell ratio between about 0.001-2. 
     
     
         10 . The battery of  claim 1 , wherein the positive electrodes comprise FeF 3 . 
     
     
         11 . The battery of  claim 1 , wherein the one or more compressible structures comprise a compressible material having a low compression set, wherein the resilience properties of the compressible structures are stable at temperatures between about 60-100° C. 
     
     
         12 . The battery of  claim 1 , wherein at least one of the compressible structures is provided in the form of a block. 
     
     
         13 . The battery of  claim 1 , wherein at least one of the compressible structures comprises at least one plate and at least one compressible member. 
     
     
         14 . The battery of  claim 13 , wherein the plate is rigid. 
     
     
         15 . The battery of  claim 13 , wherein the plate is flexible. 
     
     
         16 . The battery of  claim 13 , wherein the plate includes a mechanism for maintaining the at least one compressible member in position. 
     
     
         17 . The battery of  claim 16 , wherein the mechanism for maintaining the compressible member in position is selected from the group consisting of one or more raised members on the plate, and one or more divots in the plate. 
     
     
         18 . The battery of  claim 13 , wherein the compressible member is a spring 
     
     
         19 . The battery of  claim 18 , wherein the spring is selected from the group consisting of a cylindrical compression spring, a conical compression spring, a leaf spring, a secateur spring, a volute spring, a wave spring, and a spring washer. 
     
     
         20 . The battery of  claim 13 , wherein the compressible member is selected from the group consisting of an air spring, a gas spring, and a balloon. 
     
     
         21 . The battery of  claim 13 , wherein the compressible member is coated such that material does not flake, shear, or otherwise come off of the compressible member. 
     
     
         22 . The battery of  claim 13 , wherein the compressible member includes a block of compressible material. 
     
     
         23 . The battery of  claim 22 , wherein the compressible material is selected from the group consisting of a silicone-based foam, a polymer-based foam and a metal-based foam. 
     
     
         24 . The battery of  claim 1 , wherein each of the one or more battery stacks is sealed in a flexible pouch. 
     
     
         25 . The battery of  claim 24 , further comprising a rigid can into which the one or more pouches are inserted. 
     
     
         26 . The battery of  claim 1 , wherein the one or more compressible structures are configured to provide a uniform force over a face of the stack of electrochemically active materials. 
     
     
         27 . The battery of  claim 1 , wherein the one or more compressible structures are configured to compress the one or more battery stacks anisotropically. 
     
     
         28 . The battery of  claim 27 , wherein fiber reinforcement in the one or more compressible structures provides anisotropic compression of the one or more compressible structures. 
     
     
         29 . The battery of  claim 1 , wherein the one or more compressible structures comprise a flat plate with shapes punched into the surface, wherein the shapes are configured to deflect under an applied force from the one or more battery stacks. 
     
     
         30 . The battery of  claim 29 , wherein the flat plate with shapes punched into the surface comprises metal or polyetherimide. 
     
     
         31 . The battery of  claim 1 , wherein a face of the compressible structure is co-extensive or substantially co-extensive with a face of the one or more battery stacks. 
     
     
         32 . The battery of  claim 1 , wherein the positive electrodes comprise an electrochemically active conversion material. 
     
     
         33 . A battery pack comprising:
 (a) one or more battery stacks, each sealed in flexible pouches, wherein each of the one or more battery stacks comprise one or more unit cells, each comprising:
 (i) a positive electrode layer, 
 (ii) a lithium metal negative electrode layer, 
 (iii) an electrolyte layer positioned between the positive electrode layer and the negative electrode layer, 
 (iv) a positive current collector layer in electrical contact with the positive electrode layer, and 
 (v) a negative current collector layer in electrical contact with the negative electrode layer; and 
   (b) one or more compression structures positioned such that the one or more compression structures compress as the one or more battery stacks expand on charge, and such that the one or more compression structures expand as one or more battery stacks decrease in volume on discharge.   
     
     
         34 . A battery pack comprising:
 (a) one or more battery stacks, each sealed in flexible pouches, wherein each of the one or more battery stacks comprise one or more unit cells, each comprising:
 (i) a positive electrode layer, 
 (ii) a lithium metal negative electrode layer, 
 (iii) an electrolyte layer positioned between the positive electrode layer and the negative electrode layer, 
 (iv) a positive current collector layer in electrical contact with the positive electrode layer, and 
 (v) a negative current collector layer in electrical contact with the negative electrode layer; 
   (b) a first surface and a second surface positioned on opposite sides of the pouches; and   (c) one or more bands substantially surrounding the first surface, pouches, and second surface, wherein the bands provide an elastic force to maintain the first surface, pouches, and second surface in contact with one another, while permitting a degree of volumetric expansion within the pouches.