Manipulating the Electronic Structure of Li‐Rich Manganese‐Based Oxide Using Polyanions: Towards Better Electrochemical Performance

Abstract

Lithium‐rich manganese‐based layered oxides show great potential as high‐capacity cathode materials for lithium ion batteries, but usually exhibit a poor cycle life, gradual voltage drop during cycling, and low thermal stability in the highly delithiated state. Herein, a strategy to promote the electrochemical performance of this material by manipulating the electronic structure through incorporation of boracic polyanions is developed. As‐prepared Li[Li0.2Ni0.13Co0.13Mn0.54](BO4)0.015(BO3)0.005O1.925 shows a decreased M‐O covalency and a lowered O 2p band top compared with pristine Li[Li0.2Ni0.13Co0.13Mn0.54]O2. As a result, the modified cathode exhibits a superior reversible capacity of 300 mA h g−1 after 80 cycles, excellent cycling stability with a capacity retention of 89% within 300 cycles, higher thermal stability, and enhanced redox couple potentials. The improvements are correlated to the enhanced oxygen stability that originates from the tuned electronic structure. This facile strategy may further be extended to other high capacity electrode systems.

A high energy density Li-rich positive-electrode material with superior performances via a dual chelating agent co-precipitation route

“…S6, † however it exhibits some lattice defects including disordered area and stacking faults. 5,[34][35][36] We believe that the stable median-voltage is related to the close packing of primary grains, which then decreases the contact between the electrolyte and particle surface. Particle size distribution of both Li-rich materials is revealed in Fig.…”

Mitigating capacity fade by constructing highly ordered mesoporous Al2O3/polyacene double-shelled architecture in Li-rich cathode materials

“…Lithium-rich layered oxides (LLMO) that can be represented in two-component notation, xLi 2 MnO 3 ·(1-x)LiMO 2 (M = Ni, Co, Mn), are receiving international attention because they can deliver an exceptionally high rechargeable capacity of 250 mAh g -1 between 2.0 V and 4.8 V. [12][13][14][15][16][17] This high capacity can be achieved because lithium can be removed electrochemically from the LiMO 2 component below 4.5V with a concomitant oxidation of the M cations to a tetravalent state, and thereafter, as Li 2 O above 4.5 V from the Li 2 MnO 3 component. 16 To solve these problems, surface coating by various of metal oxides and polymers et al 24-26, 30, 32-33 , such as AlF 3 , 20 Al 2 O 3 , 21, 31, 34-35 LiAlO 2 , 22 Li 4 Ti 5 O 12 , 23 ZnO, 27 Y 2 O 3 , 28 CeF 3 , 29 have been considered as the most promising method.…”

Understanding the Stability for Li‐Rich Layered Oxide Li2RuO3 Cathode

“…[8][9][10][11][12][13][14] The common feature accounting for the high capacities of these lithium-rich layered oxides is the two redox processes involving both of cation and anion. [ 10,13,15,16 ] Despite the same process of partly charge compensation by oxygen during deep charging/discharging process, the lithiumrich layered oxides can deliver much higher reversible capacity than that of conventional cathode materials. To the best of our knowledge, such difference on the structural stability between the conventional and lithium-rich layered oxides has attracted limited attention.…”