High-Ni layered oxide cathode materials (LiNixTM(1–x)O2, where x > 0.8) are of great interest because they offer increased capacity compared to current commercial materials within a narrow voltage range. However, recent studies have shown that these materials in their current form suffer from capacity fading when an upper cutoff voltage above 4.3 V vs Li/Li+ is used. While many studies have focused on the H2 → H3 transition as the primary cause of capacity fading, gas evolution studies show that degradation processes cannot be attributed to the H2 → H3 transition alone. In this work, differential electrochemical mass spectrometry (DEMS) is combined with titration mass spectrometry (TiMS) to measure gases evolved in a lithium half-cell during cycling as well as surface species which evolve gas upon addition of strong acid to an extracted cathode. Along with qualitative observations of particle cracking by scanning electron microscopy (SEM), these results reveal correlations between particle cracking, electrolyte reactivity, and carbonate oxidation and deposition on the cathode surface during the first charge of high-Ni cathode materials.
BT - ACS Applied Materials & Interfaces DA - 09/2022 DO - 10.1021/acsami.2c09194 IS - 35 LA - eng N2 -High-Ni layered oxide cathode materials (LiNixTM(1–x)O2, where x > 0.8) are of great interest because they offer increased capacity compared to current commercial materials within a narrow voltage range. However, recent studies have shown that these materials in their current form suffer from capacity fading when an upper cutoff voltage above 4.3 V vs Li/Li+ is used. While many studies have focused on the H2 → H3 transition as the primary cause of capacity fading, gas evolution studies show that degradation processes cannot be attributed to the H2 → H3 transition alone. In this work, differential electrochemical mass spectrometry (DEMS) is combined with titration mass spectrometry (TiMS) to measure gases evolved in a lithium half-cell during cycling as well as surface species which evolve gas upon addition of strong acid to an extracted cathode. Along with qualitative observations of particle cracking by scanning electron microscopy (SEM), these results reveal correlations between particle cracking, electrolyte reactivity, and carbonate oxidation and deposition on the cathode surface during the first charge of high-Ni cathode materials.
PY - 2022 SP - 39959 EP - 39964 ST - ACS Appl. Mater. Interfaces T2 - ACS Applied Materials & Interfaces TI - Particle Surface Cracking Is Correlated with Gas Evolution in High-Ni Li-Ion Cathode Materials UR - https://pubs.acs.org/doi/10.1021/acsami.2c09194 VL - 14 SN - 1944-8244 ER -