Electrochemical behaviors of hexagonal LiMnBO3 as lithium storage host material for lithium-ion batteries

Abstract

Abstract Hexagonal LiMnBO 3 samples with particle size bewteen 0.2 and 1.0 μm are prepared by a carbothermal reaction using stoichiometric mixture of LiOH·H 2 O, Mn(CH 3 COO) 2 ·4H 2 O, H 3 BO 3 and carbon black as starting materials. Powder X-ray diffraction and infrared studies of the as-prepared products indicate that hexagonal LiMnBO 3 with space group of P-6 is formed under high temperature calcination at 750 °C. Electrochemical study shows that hexagonal LiMnBO 3 as cathode material for lithium-ion batteries can deliver an initial charge capacity of 148.4 m Ah g −1 (0.668 Li) in the potential range 2.5–4.8 V, corresponding to the delithiation plateau at 4.76 V. Combined with the charge–discharge curves, ex-situ structural investigations show that the delithiation–lithiation mechanism of hexagonal LiMnBO 3 cathode is associated with a two-phase transformation reaction. In contrast, hexagonal LiMnBO 3 as anode material for lithium-ion batteries shows a specific discharge capacity of 678.3 m Ah g −1 and corresponding specific charge capacity of 353.9 m Ah g −1 in the potential range 0.0–3.0 V. After 20 cycles, the reversible charge capacity for hexagonal LiMnBO 3 anode is 286.4 m Ah g −1 with the capacity retention of 80.9%. The excellent cycling performance is attributed to the quasi-reversible structural evolution as confirmed by ex-situ studies.