Combating Dendrites in Lithium-Ion Batteries

One of the main contributors to the fragility of lithium-ion batteries is the formation of dendrites, which are positioned alongside the surface of one or more of a battery’s electrodes; this can hamper performance and lead to serious malfunctions.

A recent study has introduced the possibility of additional chemistry in a new generation of lithium-ion batteries, which eliminates the formation of dendrites.

Researchers are confident that the new chemistry will prove to be a commercially viable alternative to the current formulation; furthermore, custom battery packs of the new cell will also prove a hit, both in the industry and in consumer market applications.

Dendrite, referring to a crystalline growth, can be found within in a compromised lithium-ion battery. As an electrode degrades, lithium metal ions from the electrolyte begin to solidify on its surface, forming finger-like structures of crystal which interfere with the inner workings of the cell.

At first, this causes decreased performance and efficiency, however once the elongated dendrite ‘fingers’ penetrate the thin barrier between the anode and cathode, catastrophic problems such as shorting and overheating can occur, ultimately leading to the destruction of the battery.

A team at the SLAC National Accelerator Laboratory have been conducting ongoing experiments for several years. Their research involved separately testing lithium nitrate and lithium polysulfide compounds, resulting in only limited success in stymieing dendrite growth.

Their breakthrough came when they decided to combine the two chemicals in the same cell, intending for it to react at the electrode, and forming an interface between the surrounding electrolyte. After a series of experiments were conducted to determine the correct quantities of each chemical, the electrode was coated not with harmful dendrites, but with benign plates of deposit. After a while they coated the electrode, providing a protective barrier and working to improve the performance of the cell.

The latest round of tests reveal that the cell treated with both compounds performed consistently better for a longer amount of time, compared to the cell with only one or neither compounds present.

These tests were encouraging a step forward in eliminating the dendrite problem in the lithium-ion market, as the technology is still in its infancy. Custom battery packs which are treated with the two compounds are not yet available, and a large-scale rollout into consumer markets is not anticipated for a long time yet.