Monodisperse MgH2 nanoparticles with homogeneous distribution and a high loading percent are developed through hydrogenation-induced self-assembly under the structure-directing role of graphene. Graphene acts not only as a structural support, but also as a space barrier to prevent the growth of MgH2 nanoparticles and as a thermally conductive pathway, leading to outstanding performance.

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Magnesium coated by different transition metals (TM: Ti, Nb, V, Co, Mo, or Ni) with a grain size in the nano-scale formed a core (Mg)–shell (TM) like structure which can catalyse dehydrogenation.

energy density of commercialized LIBs still cannot meet the requirements for practical applications. Success in these fields will mostly depend on further studying and developing new electrode materials with higher energy density.Li-and Mn-rich layered oxide (LMRO) has been considered as a promising cathode material for the next-generation LIBs due to its high energy density more than 1000 W h kg −1 . [3][4][5][6][7] However, this material also suffers from several fatal drawbacks, such as severe capacity and voltage fading during cycling, [8][9][10] poor rate performance, [5,11,12] large initial irreversible capacity. [13,14] Among these problems, the capacity and voltage fading are the key scientific issues needing to be solved first. It is generally accepted that the structure instability of the LMRO cathode material is one of the intrinsic reasons of its fast capacity and voltage fading. [15][16][17] The phase transformation from layered to spinel structure gives rise to the crystal instability when the LMRO cathode is charged to 4.8 V. [18][19][20][21] The gradual growth of spinel phase during cycling brings about the appearance of a 3.0 V plateau resulting in the voltage fading and then consequently leading to the capacity fading. [22] On the other hand, the capacity fading is also caused by the dissolution of metal elements into the electrolyte. [23,24] Zheng et al. [8] believe that the loss of MnO and NiO results in the capacity loss of the Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2 electrode because of the formation of spinel phase and subsequent fragmentation and deactivation of transition metal ions. Moreover, the dissolution of metal elements is also due to the corrosion of hydroflouric acid (HF) coming from the reaction of the residual moisture with LiPF 6 . [25] Presently, several strategies have been proposed to suppress the capacity and voltage fading of LMRO cathode material. Surface coating with inert phases is one of the effective ways, such as MnO x , [26,27] Al 2 O 3 , [28,29] MoO 3 , [13] TiO 2 , [30] ZrO 2 , [31] AlPO 4 , [32,33] AlF 3, [34,35] to stabilize the structure of the LMRO cathode materials. Choi et al. [36] reported that the 0.3Li 2 MnO 3 -0.7LiMn 0.60 Ni 0.25 Co 0.15 O 2 cathode material coated by Al 2 O 3 improved not only its discharge capacity but also its cycling stability compared with the prinstine. Guo et al. [37] discovered that the Li 1.2 Ni 0.16 Co 0.068 Mn 0.56 O 2 coated by 3 wt% MnO 2 delivered the capacity retention of 93% after 50 cycles. Chen et al. [38] demonstrated that CePO 4 layer coating onto Poor cycling stability is one of the key scientific issues needing to be solved for Li-and Mn-rich layered oxide cathode. In this paper, sodium carboxymethyl cellulose (CMC) is first used as a novel binder in Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 cathode to enhance its cycling stability. Electrochemical performance is conducted by galvanostatic charge and discharge. Structure and morphology are characterized by X-ray diffraction, scanning electronic microscopy, high-resolution transmiss...

Mg-based materials are promising candidates for high capacity hydrogen storage. However, their poor hydrogenation/dehydrogenation kinetics and high desorption temperature are the main obstacles to their applications. This paper reports a method for in situ formation of cycle stable CeH 2.73 -MgH 2 -Ni nanocomposites, from the hydrogenation of as-melt Mg 80 Ce 18 Ni 2 alloy, with excellent hydrogen storage performance. The nanocomposites demonstrate reversible hydrogen storage capacity of more than 4.0 wt %, at a low desorption temperature with fast kinetics and long cycle life. The temperature for the full hydrogenation/dehydrogenation cycle of the composites is significantly decreased to 505 K, which is about 100 K lower than that for pure Mg. The hydrogen desorption activation energy is 63 ± 3 kJ/mol H 2 for the composites, which is significantly lower than those of Mg 3 Ce alloy and pure Mg (104 ± 7 and 158 ± 2 kJ/mol H 2 , respectively). X-ray diffraction and transmission electron microscopy have been used to reveal the mechanism that delivers this excellent cycle stability and fast hydriding/ dehydriding kinetics. It is found that the hydriding/dehydriding process is catalyzed by the combination of in situ formed extremely fine CeH 2 /CeH 2.73 and Ni to Mg/MgH 2 . In addition, this nanocomposite structure can effectively suppress Mg/MgH 2 grain growth and enable the material to maintain its high performance for more than 500 hydrogenation dehydrogenation cycles.

Sodium borohydride (NaBH4) is regarded as an excellent hydrogen‐generated material, but its irreversibility of hydrolysis and high cost of regeneration restrict its large‐scale application. In this study a convenient and economical method for NaBH4 regeneration is developed for the first time without hydrides used as starting materials for the reduction process. The real hydrolysis by‐products (NaBO2·2H2O and NaBO2·4H2O), instead of dehydrated sodium metaborate (NaBO2), are applied for the regeneration of NaBH4 with Mg at room temperature and atmospheric pressure. Therefore, the troublesome heat‐wasting process to obtain NaBO2 using a drying procedure at over 350 °C from NaBO2·xH2O is omitted. Moreover, the highest regeneration yields of NaBH4 are achieved to date with 68.55% and 64.06% from reaction with NaBO2·2H2O and NaBO2·4H2O, respectively. The cost of NaBH4 regeneration shows a 34‐fold reduction compared to the previous study that uses MgH2 as the reduction agent, where H2 is obtained from a separate process. Furthermore, the regeneration mechanism of NaBH4 is clarified and the intermediate compound, NaBH3(OH), is successfully observed for the first time during the regeneration process.

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Sodium borohydride (NaBH 4 )i sa mong the most studied hydrogen storage materials because it is able to deliver high-purity H 2 at room temperature with controllable kinetics via hydrolysis;h owever,i ts regeneration from the hydrolytic product has been challenging.Now,afacile method is reported to regenerate NaBH 4 with high yield and lowc osts.T he hydrolytic product NaBO 2 in aqueous solution reacts with CO 2 ,forming Na 2 B 4 O 7 ·10 H 2 Oand Na 2 CO 3 ,both of which are ball-milled with Mg under ambient conditions to form NaBH 4 in high yield (close to 80 %). Compared with previous studies, this approach avoids expensive reducing agents such as MgH 2 , bypasses the energy-intensive dehydration procedure to removewater from Na 2 B 4 O 7 ·10 H 2 O, and does not require highpressure H 2 gas,therefore leading to much reduced costs.This method is expected to effectively close the loop of NaBH 4 regeneration and hydrolysis,e nabling aw ide deployment of NaBH 4 for hydrogen storage.