Phytate lithium as a multifunctional additive stabilizes LiCoO₂ to 4.6 V

Abstract

The practical application of LiCoO2 at 4.6 V suffers from the devastating H1-3 metastable phase transition, severe interfacial side reactions due to aggressive oxygen species and cobalt loss, as well...

A pre-fatigue training strategy to stabilize LiCoO2 at high voltage

“…Our work shows that the modified LCO exhibits superior rate performance compared to the state-of-the-art LCO materials. 31–39 Furthermore, a full cell with graphite as the anode is assembled. The cycling performance of the full cell at 1C (2.8–4.55 V) is shown in Fig.…”

Uniform Al Doping in LiCoO2 for 4.55 V Lithium-Ion Pouch Cells

“…For example, a capacity as high as 220 mAh g −1 can be obtained by increasing the charging voltage to 4.6 V. 8−11 However, at a high voltage over 4.5 V, LCO will suffer from severe problems like structural degradation, oxygen release, and parasitic reactions. 12,13 When the charging voltage reaches 4.5 V, an irreversible phase transformation (O3 → H1−3) occurs. 14 The lattice parameters will decrease, and the CoO 2 slab will slip gradually, generating tremendous residual strain inside the particles and further leading to cracks and pulverization of particles.…”

“…LCO exhibits a high theoretical capacity of 274 mAh g –1 , high electronic conductivity, and excellent air stability. , Nevertheless, the charging cutoff voltage of the commercial LCO cathode is limited to 4.45 V (vs Li/Li + ), leading to a discharge capacity lower than 180 mAh g –1 . , It is well known that increasing the charging voltage of LCO can effectively enhance the specific capacity. For example, a capacity as high as 220 mAh g –1 can be obtained by increasing the charging voltage to 4.6 V. − However, at a high voltage over 4.5 V, LCO will suffer from severe problems like structural degradation, oxygen release, and parasitic reactions. , When the charging voltage reaches 4.5 V, an irreversible phase transformation (O3 → H1–3) occurs . The lattice parameters will decrease, and the CoO 2 slab will slip gradually, generating tremendous residual strain inside the particles and further leading to cracks and pulverization of particles.…”

One-step regeneration and upgrading of spent LiFePO4 cathodes with phytic acid

“…Herein, phytic acid, as a natural and nontoxic organic large molecular compound, existing in plants and commonly used in industry as an antioxidant and polydentate metal chelating, is adopted to restore S-LFP and construct functional layers on the surface of regenerated LFP (R-LFP) for upgrading the electrochemical performance, simultaneously. In the hydrothermal treatment process, phytic acid with strong reductive properties could decrease the amount of Fe( iii ) in S-LFP, 28,29 and aqueous Li source could fill the vacancies to restore the degraded crystal structure. Meanwhile, Li ions are easily chelated by phytic acid groups, and a Li 3 PO 4 coating layer could be formed under high temperature and pressure to reconstruct the surface of R-LFP (R-LFP-LP).…”