Lithium and manganese extraction from manganese-rich slag originated from pyrometallurgy of spent lithium-ion battery

Mn and Li were selectively extracted from the manganese-rich slag by sulfation roasting−water leaching.The extraction mechanisms of Mn and Li were investigated by means of XRD,TG−DSC,and SEM−EDS.73.71%Mn and 73.28%Li were leached under optimal experimental conditions:acid concentration of 82 wt.%,acid-to-slag mass ratio of 1.5:1,roasting temperature of 800°C,and roasting time of 2 h.During the roasting process,the manganese-rich slag first reacted with concentrated sulfuric acid,producing MnSO_(4),MnSO_(4)·H_(2)O,Li_(2)Mg(SO_(4))_(2),Al_(2)(SO_(4))_(3),and H_(4)SiO_(4).With the roasting temperature increasing,H_(4)SiO_(4) and Al_(2)(SO_(4))_(3) decomposed successively,resulting in generation of mullite and spinel.The mullite formation aided in decreasing the leaching efficiencies of Al and Si,while increasing the Li leaching efficiency.The formation of spinel,however,decreased the leaching efficiencies of Mn and Li.

Phosphorus-doped lithium- and manganese-rich layered oxide cathode material for fast charging lithium-ion batteries

Owing to their high theoretical specific capacity and low cost, lithium- and manganese-rich layered oxide (LMR) cathode materials are receiving increasing attention for application in lithium-ion batteries. However, poor lithium ion and electron transport kinetics plus side effects of anion and cation redox reactions hamper power performance and stability of the LMRs. In this study, LMR Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2) was modified by phosphorus (P)-doping to increase Li+ conductivity in the bulk material. This was achieved by increasing the interlayer spacing of the lithium layer, electron transport and structural stability, resulting in improvement of the rate and safety performance. P^(5+) doping increased the distance between the (003) crystal planes from ~0.474 nm to 0.488 nm and enhanced the structural stability by forming strong covalent bonds with oxygen atoms, resulting in an improved rate performance (capacity retention from 38% to 50% at 0.05 C to 5 C) and thermal stability (50% heat release compared with pristine material). First-principles calculations showed the P-doping makes the transfer of excited electrons from the valence band to conduction band easier and P can form a strong covalent bond helping to stabilize material structure. Furthermore, the solid-state electrolyte modified P5+ doped LMR showed an improved cycle performance for up to 200 cycles with capacity retention of 90.5% and enhanced initial coulombic efficiency from 68.5% (pristine) or 81.7% (P-doped LMR) to 88.7%.

Large-scale synthesis of lithium-and manganese-rich materials with uniform thin-film Al2O3 coating for stable cathode cycling

The lithium-and manganese-rich layered oxide(LMR)holds great promise as a cathode material for lithiumion battery(LIB)applications due to its high capacity,high voltage and low cost.Unfortunately,its poor initial Coulombic efficiency(ICE)and unstable electrode/electrolyte interface with continuous growth of the solid electrolyte interphase leads to high impedance and large overpotential.These effects cause severe capacity loss and safety issues.In this work,we have developed a novel approach to fabricate a stable LMR cathode with a uniform thin layer of aluminum oxide(Al2O3)coated on the surface of the LMR particles.This synthesis approach uses the microemulsion method that is environment-friendly,cost-effective and can be easily scaled.Typically,an 8-nm layer of Al2O3 is shown to be effective in stabilizing the electrode/electrolyte interface(enhanced ICE to82.0%and moderate impedance increase over 200 cycles).Moreover,the phase transformation from layered to spinel is inhibited(96.3%average voltage retention)and thermal stability of the structure is significantly increased(heat release reduced by 72.4%).This study opens up a new avenue to address interface issues in LIB cathodes and prompts the practical applications of high capacity and voltage materials for high energy density batteries.

Optimization of manganese-rich slag extraction from low-manganese ore smelting by response surface methodology

Manganese-rich slag is a raw material for smelting silicon–manganese alloys using an electric furnace.The blast furnace method is the main method for smelting manganese-rich slag.This method has the problems of a long process,large coke consumption,and easy volatilization of metals such as lead and zinc,which affects smelting safety.A new technology for smelting manganese-rich slag with low-manganese high-iron ore by smelting reduction optimization was proposed.This technology has the advantages of a short process,low energy consumption,low carbon emissions,and comprehensive recycling of lead,zinc,and other metals.According to the chemical composition,X-ray diffraction analysis,and particle size analysis of Cote d’Ivoire low-manganese ore,an experiment was carried out on manganese-rich slag by reduction–smelting separation.Combined with the design scheme of the Box–Behnken principle,three experimental factors(temperature,basicity,and carbon content)were selected as the influences to study.The influence that each factor has on the recovery rate of manganese was studied by response surface methodology,and the experimental factors were optimized.The results show that under the conditions of a reduction-smelting temperature of 1402℃,basicity of R=0.10,and carbon content of 10 mass%,the recovery rate of manganese is 97%.A verification experiment was carried out under the optimal conditions,and the error was only 1.24%;this proves that the response surface method prediction model is reliable and accurate.This is of great significance for the comprehensive utilization of lean-manganese ore resources.

Self-reduction of Manganese-rich Slag Briquette Containing Carbon

The self-reduction experiment of manganese-rich slag briquette containing carbon was carried out in a high- temperature carbon tube furnace. The main factors affecting the reduction rate were analyzed, and the kinetic model of reduction was established. The results show that the increase of basicity of briquette has an obvious effect on im- proving reduction rate. When the carbon ratio of briquettes is 1.2 and its basicity is 1.0, the reduction rate can reach 90 %. It can accelerate reduction process and decrease reduction time when the appropriate flux CaF2 is added to the briquette. The apparent activation energy of chemical reaction is 24.07 kJ/mol, and the apparent activation energy of internal diffusion is 107.55 kJ/mol by calculation. Therefore, the reduction rate of briquette is determined by the mass transfer of CO in the product layer.

A Bifunctional-Modulated Conformal Li/Mn-Rich Layered Cathode for Fast-Charging,High Volumetric Density and Durable Li-Ion Full Cells

Lithium-and manganese-rich(LMR)layered cathode materials hold the great promise in designing the next-generation high energy density lithium ion batteries.However,due to the severe surface phase transformation and structure collapse,stabilizing LMR to suppress capacity fade has been a critical challenge.Here,a bifunctional strategy that integrates the advantages of surface modification and structural design is proposed to address the above issues.A model compound Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(MNC)with semi-hollow microsphere structure is synthesized,of which the surface is modified by surface-treated layer and graphene/car-bon nanotube dual layers.The unique structure design enabled high tap density(2.1 g cm^(−3))and bidirectional ion diffusion pathways.The dual surface coatings covalent bonded with MNC via C-O-M linkage greatly improves charge transfer efficiency and mitigates electrode degradation.Owing to the synergistic effect,the obtained MNC cathode is highly conformal with durable structure integrity,exhibiting high volumetric energy density(2234 Wh L^(−1))and predominant capacitive behavior.The assembled full cell,with nanograph-ite as the anode,reveals an energy density of 526.5 Wh kg^(−1),good rate performance(70.3%retention at 20 C)and long cycle life(1000 cycles).The strategy presented in this work may shed light on designing other high-performance energy devices.