First-principles investigation of the gas evolution from the cathodes of lithium-ion batteries during the storage test

Abstract

Gas evolution related to the positive electrode of charged lithium-ion batteries during the storage test was investigated using a first-principle method. The distribution of lithium during the delithiation process was simulated based on the density functional theory calculations of the energy required to remove the lithium from the surface or bulk crystal of lithium nickel cobalt manganese oxide (NCM) and lithium cobalt oxide (LCO). Lithium coverage of the surface was smaller for LCO than NCM at a highly charged state. The energy required to form an oxygen vacancy in NCM and LCO crystal was also calculated. The results showed that LCO was more apt to emit oxygen than NCM as the delithiation percentage was increased. The results suggest that the gas-generating side reactions related to the emission of oxygen would be more significant for LCO with high voltage charging. Experimental result showed a considerable portion of the gas was generated at the initial stages of storage for NCM, whereas LCO showed slow but steady gas evolution with increasing storage time. A large amount of Li 2 CO 3 or LiOH on the surface of NCM appears to cause an immediate gas-generating side reaction, whereas LCO produces slow side reaction related to the emission of oxygen from the LCO material itself.

Trimethyl Borate as Film-Forming Electrolyte Additive To Improve High-Voltage Performances

“…LiCoO 2 with more than 50% lithium removed is unstable in the organic electrolyte and will lose some of its oxygen. It has been shown by previous calculations and experiments that, when charged to 4.5 V, more than 70% Li will be lost and the oxygen evolution is triggered. , Therefore, extraction of too many Li + ions will lead to fast capacity fading. The evolved oxygen accumulated at the cathode during the charge process may transform into a superoxide anion radical.…”

Improving the cycling performance of LiNi0.8Co0.1Mn0.1O2 by surface coating with Li2TiO3

“…The knowledge we have gain from crystallography enabled us to realize that it is harder for Ti 4+ ion to migrate into the bulk material in crystal structure compared with that in amorphous structure [24]. In order to figure the coating layer out, different amounts of LiOH•H 2 O were added into crystalline TiO 2 and heating 9 treatment was processed at 480 ℃ for 5 h, and then at 800 ℃ for 15 h in oxygen. powder with a diameter > 13.8 m cracked (Fig.…”

“…Conventional electrolyte can be oxidized at the surface of the cathode and the surface lattice structure of cathode materials suffer from an irreversible transformation at high potentials. This can lead to many problems such as low capacity retention, loss of active lithium inventory, gas formation, and increased viscosity of the electrolyte due to solvent loss [7,9]. So，Ni-rich materials, such as Unfortunately, the Ni-rich materials have so far been hindered by the low initial coulombic efficiency, poor cycling performance, poor storage performance, instability between electrode and electrolyte as well as high thermal instability [10].…”

In Situ Analysis of Gas Generation in Lithium-Ion Batteries with Different Carbonate-Based Electrolytes

“…Currently, lithium-ion batteries (LIBs) have been widely used in portable electronics and power tools due to its high energy density. − Despite the major advances over the last few decades, gas generation during the formation, operation, and storage of the LIBs remains a big challenge, because of the concomitant volume swelling, performance failure, and safety concerns. − Gas generation in the formation step of the batteries is mainly originated from the electrochemical decomposition of electrolyte solvents during the solid-electrolyte interphase (SEI) layer formation, − which requires an extra degassing process, especially for the “soft” pouch cells, and thus increases the production cost and potentially degrades the consistency of cell groups. Comparatively, gas releasing during cycling and storage of well-formed cells is generally less severe if no abuse condition such as overcharging or overheating is applied.…”