Nanoscale Surface Modification of Lithium‐Rich Layered‐Oxide Composite Cathodes for Suppressing Voltage Fade

Abstract

Lithium‐rich layered oxides are promising cathode materials for lithium‐ion batteries and exhibit a high reversible capacity exceeding 250 mAh g−1. However, voltage fade is the major problem that needs to be overcome before they can find practical applications. Here, Li1.2Mn0.54Ni0.13Co0.13O2 (LLMO) oxides are subjected to nanoscale LiFePO4 (LFP) surface modification. The resulting materials combine the advantages of both bulk doping and surface coating as the LLMO crystal structure is stabilized through cationic doping, and the LLMO cathode materials are protected from corrosion induced by organic electrolytes. An LLMO cathode modified with 5 wt % LFP (LLMO–LFP5) demonstrated suppressed voltage fade and a discharge capacity of 282.8 mAh g−1 at 0.1 C with a capacity retention of 98.1 % after 120 cycles. Moreover, the nanoscale LFP layers incorporated into the LLMO surfaces can effectively maintain the lithium‐ion and charge transport channels, and the LLMO–LFP5 cathode demonstrated an excellent rate capacity.

Novel MOF shell-derived surface modification of Li-rich layered oxide cathode for enhanced lithium storage

“…The NiCo alloy nanodots with a diameter of around 5 nm are distributed in the derived carbon shell. The measured interlayer distance of 0.47 nm is in agreement with the (0 0 3) plane of the layered structure [35]. The corresponding SAED pattern ( Fig.…”

“…One efficient and simple method to solve the aforementioned problems and improve the electrochemical performance is via doping elements in crystal lattices of LLO by ions, such as Mg 2+ [13], Al 3+ [27], F À [28] and (BO 3 ) 3À [29], to supersede transition metal or lithium ions. Another efficient approach is surface modification of LLO by coating a thin layer of protective materials, including AlF 3 [30], Al 2 O 3 [31], AlPO 4 [32], Li 2 ZrO 3 [33], LiCoPO 4 [34] and LiFePO 4 [35]. For instance, Zheng et al [35] designed a surface modification with LiFePO 4 , which provides lithium ion and charge transport channels as well as protects the surface structure from side reactions at the electrode/electrolyte interface.…”

“…Another efficient approach is surface modification of LLO by coating a thin layer of protective materials, including AlF 3 [30], Al 2 O 3 [31], AlPO 4 [32], Li 2 ZrO 3 [33], LiCoPO 4 [34] and LiFePO 4 [35]. For instance, Zheng et al [35] designed a surface modification with LiFePO 4 , which provides lithium ion and charge transport channels as well as protects the surface structure from side reactions at the electrode/electrolyte interface. Moreover, surface modification via carbon coating has been widely applied to cathode materials (e.g., LiFePO 4 [36], Li 2 MnO 4 [37], and LiNi 1/3 Mn 1/3 Co 1/3 O 2 [38]) to provide enhanced structure stability and high electronic conductivity, thereby improving the rate capability and cycling performance [39].…”

Synthesis and electrochemical performance of micro-sized Li-rich layered cathode material for Lithium-ion batteries

“…In order to overcome these defects, considerable efforts have been devoted, such as doping, coating, surface treatment and nano-crystallization [11][12][13][14][15][16]. Among all the modified methods, nano-crystallization is the most widely used strategy to enhance their discharge capacities and rate capabilities owing to short diffusion length and large active surface areas [11,17,18].…”

A novel lithium-ion battery comprising Li-rich@Cr2O5 composite cathode and Li4Ti5O12 anode with controllable coulombic efficiency

“…However, these Li-rich electrodes have natural defects such as poor rate performance, gradual voltage decay and low initial coulombic efficiency (ICE, about 75%) [11,12]. Though the voltage decay and poor rate performance can be alleviated by taking some measures like lattice doping, surface coating and morphology design [13][14][15][16][17][18][19][20][21], the capacity fading (about 25%) caused by the irreversible transformation of Li 2 MnO 3 phase in Li-rich from layered-structure to spinel-structure LiMn 2 O 4 with the release of Li + and oxygen in the first cycle is practically unavoidable, which is a challenge for their applications in LIBs as before [22][23][24]. At present, ongoing research efforts mainly concentrate on conquering the large irreversible capacity loss counterbalanced by anode materials with similar percentage of initial irreversible capacity loss, such as carbon [25][26][27], transition metal oxides [28] and composite Si/C or Sn/C [29][30][31].…”