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Abstract In this paper, we demonstrate for the first time the synthesis of spinel LiMn 2 O 4 using by-products of the electrolytic manganese through solid state reaction. LiMn 2 O 4 synthesized through by-products from coated titanium anodes exhibits a special biscuit-like hierarchical micro/nano structure and excellent electrochemical performance. When used as cathode material in lithium ion batteries, it delivers an initial discharge capacity of 119.1 mA h g−1 at 14.8 mA g−1, and high reversible discharge capacities of 94.1 mA h g−1 and 75.4 mA h g−1 can be maintained when the current density reach 740 and 1480 mA g−1. High capacity retention of about 90% can be also achieved after 200 cycles in the potential range of 3–4.3 V at 148 mA g−1. The electrochemical performance is much superior to that of the counterpart sample synthesized by conventional electrolytic manganese dioxide which can be ascribed to the unique hierarchical micro/nano architecture. However, on the other side, LiMn 2 O 4 synthesized by Pb anode slime suffer from poor electrochemical performance due to the inevitable Pb issue and other relevant impurities. These results may open up a new gate for the further application of by-product of electrolytic manganese. [ABSTRACT FROM AUTHOR]

Electrowinning is a vital process for the production of metal manganese, however, always suffer from low cathodic current efficiency and nodule issues. Herein, a new concept involving cylindrical cell and rotary electrolysis is proposed and demonstrated for manganese electrowinning process. Results indicate that manganese deposits on cylindrical cathode are uniform and the edge effect is effectively suppressed. The cathodic current efficiency increases from 77.65% to 82.56% and the corresponding energy consumption decreases from 5.29 kWh/kg to 4.27 kWh/kg with the comparison of traditional plate electrolytic cell. Based on the above results, fluid field is further introduced by stirring catholyte and rotating cathode respectively. The fluid field can refine manganese grains and significantly inhibit the formation of manganese nodules. Under the proper cathode rotating speed, the cathodic current efficiency reaches 86.22% and ideal compact flat electrolytic manganese flakes can be obtained. Our strategy here may also inspire other researchers especially in electrochemical fields to improve energy and mass efficiencies for a bubble-involving chemical process. Cylindrical electrode was applied to manganese electrowinning process, boosting both energy and mass efficiencies for this bubble-involving reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

Li- and Mn-rich layered oxides are receiving considerable attentions for the next-generation commercial lithium ion batteries owing to their high capacity and low cost. However, there is still some dispute about the ideal synthesis protocol to obtain the optimum electrochemical performances. Herein, we deeply explore the decomposition/lithiation mechanisms of sodium-contained Ni 1/6 Co 1/6 Mn 4/6 CO 3 precursor (NCM-P) during calcination process, and highlight the effects of heat treatment temperature and the lithium to NCM-P molar ratio (Li/ TM) on Li- and Mn-rich layered oxides. The results demonstrate that Ni 1/6 Co 1/6 Mn 4/6 CO 3 can be initially lithiated to LiNi 1/6 Co 1/6 Mn 4/6 O 2 , then gradually lithiated/decomposed to 0.1/6Li 4 Mn 5 O 12 ·2.5/6Li 2 MnO 3 ·0.5LiNi 1/3 Co 1/3 Mn 1/3 O 2 material. The cathode crystal crystallization and the components are significantly affected by heat treatment temperature and the Li/ TM ratios. The optimized synthetic conditions for Li- and Mn-rich cathode materials is in 500 °C for 4 h, 750 °C for 4 h, and 840 °C for 10 h under Li/ TM = 1.4. Under this condition, the synthesized Li- and Mn-rich oxides can deliver a first discharge capacity of 259.4 mAh·g−1 at 25 mA g−1 with 84.00% coulombic efficiency, and 218.2 mAh·g−1 at 250 mA g−1 with 90.97% capacity retention after 100 cycles. This study would give some guidance for the synthesis of Li-rich layered oxides. • High-performance Li- and Mn-rich oxides are synthesized by solid-state method. • The lithiation mechanisms of Ni 1/6 Co 1/6 Mn 4/6 CO 3 have been explored. • The sodium and lithium jointly control the physiochemical property of Li-rich oxide. • The synthesized Li-rich oxide delivers a discharge capacity of 218.2 mAh·g−1 at 250 mA g−1 • The study provides a guidance for the synthesis of Li- and Mn-rich layered oxide. [ABSTRACT FROM AUTHOR]

• Li 2 RuO 3 is first reported as coating material for LLOs. • LRO layer could form electronic/ionic highways on the surface of cathode material. • The interfacial stability and conductivity of cathode material were enhanced. • The electrochemical performance was greatly improved after incorporation of LRO. The interfacial property of cathode materials in Li-ion batteries plays a vital role for the mass transport in electrochemical process. In this paper, Li 2 RuO 3 coating layer, acting as an electronic/ionic conductive network, is introduced to lithium-rich Mn-based material that is known for its low rate capability and quick capacity fading. The reaction kinetics are promoted due to the depolarizing effect of this modified layer. The target material achieves a discharge capacity as high as 195.4 and 150.6 mAh g−1 at 2C and 8C, respectively. The conductive Li 2 RuO 3 coating layer helps to accelerate the transport of Li ion and electron at grain surface and relieve phase transformation, ultimately reducing the reaction resistance. Cycle stability is also enhanced (capacity retention of 92% after 100 cycles) by mitigating side reactions between cathode and electrolyte. This study provides an effective approach to ameliorate the sluggish Li-ion transport of lithium-rich Mn-based material and other analogous cathode materials. [ABSTRACT FROM AUTHOR]

• 4-fluorophenylboronic anhydride (TFTB) was employed as a multifunctional electrolyte additive for lithium ion batteries. • The TFTB exhibits unique H 2 O/HF impurity scavenging effect. • The TFTB simultaneously stabilizes the two-sided interfaces on both Si-C anode and NCM cathode. • The TFTB endows the NCM/Si-C full cell with improved reversible capacity and cycle performance. In this work, an electrolyte optimization strategy is proposed for simultaneously stabilizing the two-sided interfaces in the LiNi 0.5 Co 0.3 Mn 0.2 O 2 (NCM)/Si-C batteries by employing a multifunctional additive, 4-fluorophenylboronic anhydride (TFTB). It is revealed that the TFTB is capable of scavenging the trace amount of moisture and HF acidic species in the electrolyte by strongly coordinating with them, meanwhile, possesses preferential reduction/oxidation sequence in contrast to conventional carbonate solvents. Profited from these synergistic effects from the additive, favorable interface chemistry can be simultaneously built on both Si-C anode and NCM cathode accompanied by greatly suppressed electrolyte degradation, which not only well accommodates the volume change of the Si-C anode during cycling, but also effectively protects the NCM cathode from structural destruction. Consequently, the addition of the TFTB endows the NCM/Si-C full cell with improved reversible capacity and cycle performance. [ABSTRACT FROM AUTHOR]

Precious metal-free bifunctional electrocatalysts with efficient performance to ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) are the prerequisite to the commercialization of rechargeable Zn-air battery (RZAB). Here, ultrathin amorphous MnO 2 modified prawn shells-derived porous carbon (U–MnO 2 /PSNC) is designed and synthesized via a self-template assisted pyrolysis coupling in-situ redox reaction strategy. In this composite, the ultrathin amorphous MnO 2 provides high surface defects and homogeneous catalytic active sites. The conductive prawn shells-derived porous carbon displays macro-meso-microporous structure, promoting electric conductivity and offering fast pathway for mass diffusion. With optimized composition, the U–MnO 2 -0.01/PSNC delivers an excellent bifunctional to ORR/OER with a small ΔE (bifunctional activity parameter) value of 0.776 V. Moreover, the RZAB equipped with U–MnO 2 -0.01/PSNC displays a considerable stability with narrow decay of battery efficiency (1.10%) for ∼334 h (500 cycles) at 10 mA cm−2. This work enlightens a new pathway to design cost-effective bifunctional electrocatalysts for metal-air battery. [ABSTRACT FROM AUTHOR]