| Energy storage devices based on lithium-ions play the key roles in the energy storage market owing to their high specific energy,high operating voltage and high efficiency.However,the limited theoretical capacity and low reaction kinetics of graphite anode limits the energy and power densities of lithium-ion batteries.Therefore,it is desirable to develop novel and high-performance anode materials for lithium-ion batteries.Here,porous carbon and its composite with transition metal oxides have been designed as advanced anode materials for lithium-ion batteries.The lithium-ion storage performances of these anode materials have been tuned by the different porous architectures and the different solid/solid interfacial properties with Mn O.As a result,the hard carbon and its composite with Mn O have been investigated as advanced anode materials for high-performance lithium-ion batteries.The investigations can be described as follows:Firstly,the microstructures of hard carbon materials have been tuned by the different annealing temperatures and the templating and activation effects of Zn O,giving rise to superior performance for lithium-ion storage.On the one hand,the annealing temperature has been tuned to optimize the microstructures of hard carbon(such as the microcrystalline structure,micropore,specific surface area and pore volume),giving rise to better performance in terms of specific capacity,rate performance and cycle stability.On the other hand,the porous architecture of hard carbon has been tuned for optimized lithium-ion storage performance.By tuning the annealing temperature,a series of hierarchical porous carbons are synthesized by high-temperature pyrolysis method,and superior lithium-ion storage performance can be achieved by optimizing the hierarchical porous architectures.Amongst,the HPC-1200 achieves the highest specific capacity of1850 m Ah g–1 at 0.1 A g–1 combined with excellent rate and ultralong-term cycling stability.More significantly,the as-synthesized hard carbons are used to assemble full batteries with conmmercial Li Ni0.5Co0.2Mn0.3O2,which can achieve high specific energy,high specific power and ultra long cycle performance at the same time.Secondly,porous carbon encapsulated Mn O composite is transformed from Zn-Mn based bimetal organic framework(Zn Mn-MOF)with the highly porous architecture of porous carbon can buffer the volume change of Mn O and thus superior lithium-ion storage can be realized.The Mn O/porous carbon composite is converted from Zn Mn-MOF by annealing at elevated temperature.The porous carbon improves the electronic conductivity and interfacial performance of Mn O with electrolyte.The results show that the Mn O/porous carbon composite achieves high specific capacity,excellent rate and long cycle stability when used as the anode material for lithium-ion batteries.More significantly,the Mn O/porous carbon composite is assembled into lithium-ion capacitors with commercial activated carbon,and both high specific energy and specific power densites up to 153.6 Wh kg?1 and 63.0 k W kg?1 can be achieved,respectively.Lastly,the solid/solid interfacial properties are improved to optimize the lithium-ion storage performance of Mn O/porous carbon composite combined with the improved performance from porous architecture which can buffer the volume change of Mn O during lithiation.The porous carbon dispersed Mn O electrode materials were prepared by one-step calcination method with the mixture of organic carbon source,manganese and zinc salts.Owing to the carbothermal reduction reaction between manganese and zinc oxides,large pores can be formed between the Mn O and carbon matrix solid/solid interface,which provides extra space to buffer the volume change for the lithiation/delithiation of Mn O.Owing to the combined contributions from the porous architecture of porous carbon and the special solid/solid interface with Mn O,enhanced rate performance and cycling stability can be achieved by the Mn O/porous carbon composite. |
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