High Energy Density Semi-Solid Storage Electrodes and Batteries Thereof

Technology      

The design of these flow electrodes combines redox active solution electrodes and active solid electrodes, forming suspensions of the latter in the former. These suspensions are percolating networks in the flowable redox solutions created by diffusion-limited aggregation. This creates an “infinite current collector” network that allows the electrochemical reaction to be carried out throughout the volume of an electrode. These networks can be created with the storage particles and/or additive materials that are electronically conductive. This design increases the electroactive area by 103 while providing sufficient electronic conductivity and retaining flowability. Currently, reversibility limitations are attributed to thick layers of insulating lithium disulfide (Li2S2) and lithium sulfide (Li2S) on the electrodes. The greater surface area of this design allows an equivalent volume of Li2S2 and Li2S to deposit as a thinner layer, which reduces transfer resistance and increases reversibility.  For identical solutions, cell geometry, and electrochemical test conditions, the cell with nanoconductor suspension exhibits 5 times the capacity of the conventional flow cell design, and reached the theoretical capacity of the solution.  

Problem Addressed

Currently, the electrochemical reaction in flow batteries only occurs on the surface of the electrodes. This design allows the reaction to occur throughout the volume of the electrode, and improves the battery capacity and reversibility when cycled to include the precipitation regime.  

Advantages      

• Increased flow battery capacityIncreased flow battery reversibility