Preparation of LiNiO₂ Using Fluorine-modified NiO and Its Charge-discharge Properties

Abstract

A Ni(OH) 2 surface was fluorinated at 25°C using F 2 gas for 1 h under absolute pressure of 6.67 kPa. Some fluorides and oxyfluorides were detected only on the Ni(OH) 2 particle surface, although most Ni(OH) 2 remained inside of the particles. Fluorine-introduced NiO (NiO(F)) was obtained by heating the surface-fluorinated Ni(OH) 2 . After sintering at 750°C for 6 h, the NiO(F) crystal size and surface area were, respectively, 0.6 times smaller and 4.7 times larger than those of NiO obtained from untreated Ni(OH) 2 . LiNiO 2 samples were prepared via reaction between NiO(F) and Li 2 CO 3 at 700°C for 20 h and 30 h, respectively (LiNiO 2 (20 h, F) and LiNiO 2 (30 h, F)). The density of LiNiO 2 (30 h, F) was 4.697, which was larger than the 4.556 of LiNiO 2 prepared from NiO and Li 2 CO 3 under the same conditions. The discharge capacity of LiNiO 2 (30 h, F) was 202 mAh g −1 , whereas the LiNiO 2 prepared under the same condition from NiO and Li 2 CO 3 was 172 mAh g −1 . The discharge capacity of LiNiO 2 as a cathode of LIB might be improved by introducing fluorine to its preparation process between NiO and Li 2 CO 3 .

Electrodeposition of Silicon Fibers from KI–KF–KCl–K2SiF6 Melt and Their Electrochemical Performance during Lithiation/Delithiation

“…This can be achieved using anode materials with a capacitance exceeding that of graphite. Promising materials are silicon (discharge capacity up to 4200 mAh g −1 ) [2,3], germanium (up to 1624 mAh g −1 ) [4,5], transition metal oxides (up to 1200 mAh g −1 ) [6,7], etc. Many of the above-mentioned materials cannot be used as an anode for a lithium-ion current source due to significant volume expansion (silicon-up to 300%, germanium and transition metal oxides-up to 100-200%, graphite-no more than 10%).…”

Improved Electrode Reversibility of Nanosized Li_1.15Nb_0.15Mn_0.7O₂ through Li₃PO₄ Integration

“…To satisfy the rapidly growing demand for lithium-ion batteries (LIBs) in the global market, the scientific community is focused on developing high-performance electrode materials. [1][2][3][4][5][6][7] Among several candidates, Li-excess oxides with a cation-disordered rocksalt (DRS) structure are promising positive electrode materials due to their high theoretical capacities (>350 mA h g -1 ). [8][9][10][11][12] DRS oxides used to be disregarded as a positive electrode material because of the absence of a lithium migration path in DRS structure.…”