High conductivity pristine copper particles and carbon coated Li 2 ZnTi 3 O 8 composite (Li 2 ZnTi 3 O 8 /C@Cu) is prepared by one-step sol-gel method followed by high temperature pyrolysis. Amorphous carbon coating layer reveals a thickness of 2.0-8.0 nm on the outer surface of Li 2 ZnTi 3 O 8 active grains, which improves the electronic conductivity and charge transfer rate of primary and secondary particles. Moreover, copper particles between particles could enhance the electronic transmission at large current densities and decrease diffusion resistance. As a result, Li 2 ZnTi 3 O 8 /C@Cu composite shows lower electrochemical polarization and quicker kinetic behavior compared to Li 2 ZnTi 3 O 8 /C. Cycled at 1000 mA g-1 , 2000 mA g-1 , and 3000 mA g-1 , Li 2 ZnTi 3 O 8 /C@Cu can deliver a reversible capacity of 124.4 mAh g-1 , 90.8 mAh g-1 , and 79.1 mAh g-1 after 1000 cycles, which is much higher than the values of 70.7 mAh g-1 , 75.5 mAh g-1 , and 52.1 mAh g-1 obtained by Li 2 ZnTi 3 O 8 /C. In addition to higher specific capacity, electrode polarization and cycle stability have been improved after adding copper particles. The improved electrochemical properties of Li 2 ZnTi 3 O 8 /C@Cu composite are attributed to the combination of copper additive and carbon layer.

Al2O3-coated layered oxide Li1.2Mn0.54Ni0.13Co0.13O2 (AO-LMNCO) is synthesized by a facile sol-gel reaction to prepare a preliminary formation of Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO), and then coating process with Al2O3 nano layer is followed via a chemical deposition route. Galvanostatic charge-discharge tests show that 1.5 wt% Al2O3 coated sample presents the optimum electrochemical performance. It delivers a discharge capacity 285 mAh g-1 in the potential window of 2.0-4.8 V at 0.2 C, which is superior to that 274 mAh g-1 for the pristine one. The initial columbic efficiency is significantly enhanced from 80.60% to 87.40% after the coating process. Moreover, the optimal sample presents a superior high-rate capacity of 120 mAh g-1 at 10 C, and the value is much greater than the pristine one. Physical characterization results show that the as-prepared Li-rich oxide has a typical layered structure, and the Al2O3 nano layer (~4 nm thick) is coated on the surface of the cathode grains. We could ascribe the remarkably enhancement of cycling stability and high-rate capability to the Al2O3 protective coat, which could obstruct the electrolyte from the close contact with the active material. Thus the corrosion of the electrode structure effectively decreases and the dissolution of Mn from the pristine material greatly suppresses.

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