Composition of thick cathodes in all-solid-state lithium batteries impacts electrochemical reactions, reveals study

The development of better batteries is crucial for advancing electric transportation and addressing climate change. All-solid-state lithium batteries (SSBs) are a promising technology due to their enhanced safety and stability compared to traditional lithium-ion batteries. They also offer the potential for higher energy densities, leading to longer-lasting and more compact batteries for various applications.

A recent study led by Joshua Gallaway of Northeastern University and scientists at the Department of Energy’s Argonne National Laboratory focused on investigating the impact of cathode composition on electrochemical reactions in SSBs. The team utilized the Advanced Photon Source (APS), a facility at Argonne, to analyze the batteries. Their findings were published in the journal ACS Energy Letters.

Gallaway drew an analogy between batteries and sandwiches, explaining that they consist of an anode, a cathode, a separator, and electrolyte solution. In SSBs, the solid electrolyte eliminates the need for traditional separators, but they require thick cathodes.

In their research, Gallaway and his colleagues examined batteries with thick cathodes composed of two materials: a sulfide solid electrolyte called LPSC and an NMC cathode active material (CAM). They varied the composition of these materials, resulting in batteries with different ratios of CAM and LPSC. X-ray imaging and scattering at the APS were used to measure slices within the cathode and solid-state electrolyte.

By investigating electrochemical reactions within the batteries, Gallaway and physicist John Okasinski from APS discovered that the composition of the cathode significantly influenced these reactions. For instance, in an SSB with an 80% CAM cathode, the slice closest to the anode reacted first, while the farthest slice reacted last. However, in an SSB with a 70% CAM cathode, the farthest slice reacted first, and the nearest slice reacted last.

Gallaway emphasized the non-uniform nature of these reactions, which could lead to accelerated degradation of the battery material. Understanding the intricacies of these reactions is crucial for designing improved batteries for electric vehicles, portable electronics, and other applications. The design of all-solid-state batteries will ultimately determine their potential applications and optimization in the future.

Source: Argonne National Laboratory

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