US 8,945,737 B2 · Application of force in electrochemical cells

Abstract

The present invention relates to the application of a force to enhance the performance of an electrochemical cell. The force may comprise, in some instances, an anisotropic force with a component normal to an active surface of the anode of the electrochemical cell. In the embodiments described herein, electrochemical cells (e.g., rechargeable batteries) may undergo a charge/discharge cycle involving deposition of metal (e.g., lithium metal) on a surface of the anode upon charging and reaction of the metal on the anode surface, wherein the metal diffuses from the anode surface, upon discharging. The uniformity with which the metal is deposited on the anode may affect cell performance. For example, when lithium metal is redeposited on an anode, it may, in some cases, deposit unevenly forming a rough surface. The roughened surface may increase the amount of lithium metal available for undesired chemical reactions which may result in decreased cycling lifetime and/or poor cell performance. The application of force to the electrochemical cell has been found, in accordance with the invention, to reduce such behavior and to improve the cycling lifetime and/or performance of the cell.

Claims18

Dependent claims

An electrochemical cell comprising:

a cathode comprising sulfur as a cathode active material;
an anode comprising lithium metal and/or a lithium alloy as an anode active material, the anode having an active surface;
and
an electrolyte in electrochemical communication with the cathode and the anode;
wherein the cell is constructed and arranged to apply, during at least one period of time during charge and/or discharge of the cell, an anisotropic force with a component normal to the active surface of the anode, the force including the component selected to define a pressure that affects surface morphology of the anode active surface to inhibit an increase in anode active surface area through charge and discharge, the pressure being of at least about 98 Newtons per square cm and less than about 196 Newtons per square cm, and wherein, in the absence of the anisotropic force but under otherwise essentially identical conditions, the anode active surface area is increased to a greater extent through charge and discharge cycles.

2 more elements

Dependencies are inferred from the claim text.

Application of force in electrochemical cells

Life of this patent

Application of force in electrochemical cells

Life of this patent

Abstract

Claims18