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Improved Rate Capability of Li‐Rich Cathode Materials by Building a Li + ‐Conductive Li x BPO 4+ x /2 Nanolayer from Residual Li 2 CO 3 on the Surface
Author(s) -
Ma Leilei,
Li Yang,
Chen Zonghai,
Zhang Fan,
Ding Pengchong,
Mao Lei,
Lian Fang
Publication year - 2017
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201700157
Subject(s) - materials science , current density , cathode , lithium (medication) , ion , diffusion , conductivity , electrode , chemical engineering , composite material , thermodynamics , chemistry , medicine , physics , organic chemistry , quantum mechanics , engineering , endocrinology
Lithium‐ and manganese‐rich layered oxides face great challenges for practical applications, including gradual voltage decay upon normal charge/discharge cycling and the relatively low volumetric energy density. This series of materials generally suffer from a great reduction in reversible capacity with an increase of the current density and the loading density of the electrode, which can be attributed to the low Li + conductivity of the material, as previously reported. Herein, BPO 4 is proposed to encapsulate Li 1.16 (Ni 0.25 Mn 0.75 ) 0.84 O 2 (LNMO) particles and is expected to form a Li‐doped Li x BPO 4+ x /2 (LBP) layer as a lithium‐ion conductor on the particle surface to facilitate the transportation of Li + across the solid−liquid interface. The results confirm that the LBP layer was formed, providing a lithium‐ion diffusion path and suppressing the undesired interfacial reactions. A LNMO sample coated with 1.6 mol% LBP (LBP@LNMO) demonstrated excellent rate capability, retaining 90.2, 80.2, 61.2, and 43.5 % at 1, 2, 5, and 10 C rates of the capacity at the 0.5 C rate. Moreover, the modified material is clearly relieved from voltage fading and offers improved cycling stability at 55 °C, which mainly contributes to a decrease in the polarization and an increase in the interfacial stability under the protection of the LBP layer. It implies that the dual functional coating is an effective route to promote the lithium‐transport kinetics.