Beneficial impact of lithium bis(oxalato)borate as electrolyte additive for high‐voltage nickel‐rich lithium‐battery cathodes

• Published in: InfoMat Vol. 5; no. 8
• Main Authors: Wu, Fanglin, Mullaliu, Angelo, Diemant, Thomas, Stepien, Dominik, Parac‐Vogt, Tatjana N., Kim, Jae‐Kwang, Bresser, Dominic, Kim, Guk‐Tae, Passerini, Stefano
• Format: Journal Article
• Language: English
• Published: Melbourne John Wiley & Sons, Inc 01.08.2023; Wiley
• Subjects: Additives; Boron; cathode electrolyte interphase; Cathodes; Cathodic protection; Cycles; Decomposition; Decomposition reactions; Electrochemical analysis; Electrode materials; Electrodes; electrolyte additive; Electrolytes; Energy; high voltage cathodes; High voltages; Interface stability; LiBOB; Lithium; Lithium batteries; Lithium borates; Microcracks; Nickel; nickel‐rich cathodes; Phase transitions; Spectrum analysis; Structural stability
• ISSN: 2567-3165; 2567-3165
• DOI: 10.1002/inf2.12462

High‐voltage nickel‐rich layered cathodes possess the requisite, such as excellent discharge capacity and high energy density, to realize lithium batteries with higher energy density. However, such materials suffer from structural and interfacial instability at high voltages (>4.3 V). To reinforce the stability of these cathode materials at elevated voltages, lithium borate salts are investigated as electrolyte additives to generate a superior cathode‐electrolyte interphase. Specifically, the use of lithium bis(oxalato)borate (LiBOB) leads to an enhanced cycling stability with a capacity retention of 81.7%. Importantly, almost no voltage hysteresis is detected after 200 cycles at 1C. This outstanding electrochemical performance is attributed to an enhanced structural and interfacial stability, which is attained by suppressing the generation of micro‐cracks and the superficial structural degradation upon cycling. The improved stability stems from the formation of a fortified borate‐containing interphase which protects the highly reactive cathode from parasitic reactions with the electrolyte. Finally, the decomposition process of LiBOB and the possible adsorption routes to the cathode surface are deduced and elucidated. A boron‐containing electrolyte additive is proposed and investigated for high voltage nickel‐rich cathode (≥4.6 V), enabling an enhanced cycling stability and significantly suppressed voltage hysteresis due to the formation of a superior robust borate‐containing interphase layer, which highlights the possibility to break through the capacity bottleneck of nickel‐rich cathodes and achieve high‐energy‐density lithium‐metal battery.