Search

Background and Aims Zinc (Zn) is an essential element for humans and plants. However, Zn deficiency is widespread and 25 % of the world’s population is at risk of Zn deficiency. To overcome the deficiency of Zn intake, crops with high Zn content are required. However, most crop-producing areas have Zn-deficient soils, therefore crops with excellent Zn uptake/transport characteristics (i.e. high Zn efficiency) are needed. Our objective was to identify the crucial factors responsible for high Zn efficiency in the legume Lotus japonicus. Methods We evaluated Zn efficiency by static and real-time visualization of radioactive Zn (65Zn) uptake/transport in two L. japonicus accessions, MG-20 and B-129, that differ in Zn efficiency. The combination of visualization methods verified the dynamics of Zn accumulation and transport within the plant. We compared gene expression under a normal Zn concentration (control) and Zn deficiency to evaluate genetic factors that may determine the differential Zn efficiency of the accessions. Key Results The accession B-129 accumulated almost twice the amount of Zn as MG-20. In the static 65Zn images, 65Zn accumulated in meristematic tissues, such as root tips and the shoot apex, in both accessions. The positron-emitting tracer imaging system (PETIS), which follows the transport process in real time, revealed that 65Zn transport to the shoot was more rapid in B-129 than in MG-20. Many genes associated with Zn uptake and transport were more highly expressed in B-129 than in MG-20 under the control condition. These gene expression patterns under Zn deficiency differed from those under the control Zn condition. Conclusions PETIS confirmed that the real-time transport of 65Zn to the shoot was faster in B-129 than in MG-20. The high Zn efficiency of B-129 may be due to the elevated expression of a suite of Zn uptake- and transport-related genes.

This research provides insight into a unique salt tolerance mechanism of Vigna riukiuensis. V. riukiuensis is one of the salt-tolerant species identified from the genus Vigna. We have previously reported that V. riukiuensis accumulates a higher amount of sodium in the leaves, whereas V. nakashimae, a close relative of V. riukiuensis, suppresses sodium allocation to the leaves. We first suspected that V. riukiuensis would have developed vacuoles for sodium sequestration, but there were no differences compared to a salt-sensitive species V. angularis. However, many starch granules were observed in the chloroplasts of V. riukiuensis. In addition, forced degradation of leaf starch by shading treatment resulted in no radio-Na (22Na) accumulation in the leaves. We performed SEM–EDX to locate Na in leaf sections and detected Na in chloroplasts of V. riukiuensis, especially around the starch granules but not in the middle of. Our results could provide the second evidence of the Na-trapping system by starch granules, following the case of common reed that accumulates starch granule at the shoot base for binding Na.

福島原発事故後、放射性セシウムは長期間に渡り樹木内に保持されていた。これは樹木の生長・活動に利用される栄養元素と共に樹木内を移動するため、樹体外へ排出されにくいからと考えられている。今後起こり得る原発事故のリスクを正確に評価するため、放射性セシウムの輸送とそれを制御する分子メカニズムを明らかとする必要があるが、樹木のセシウム動態とその制御遺伝子については不明な点が多い。本発表では、放射性セシウム（Cs-137）を用いた樹木ポプラ内のセシウム輸送とその季節変動の観察、そしてその輸送を制御するPttSKOR-like2輸送体について紹介する。, QST高崎サイエンスフェスタ2021

放射性セシウムは福島原発事故後、長期間に渡り樹木内に保持されていた。これは、放射性セシウムが樹木の生長・活動に利用される栄養元素と共に樹木内を移動するため、樹体外へ排出されにくいからである。今後起こり得る原発事故のリスクを正確に評価するため、放射性セシウムの輸送とそれを制御する分子メカニズムを明らかとする必要があるが、樹木のセシウム動態とその制御遺伝子については不明な点が多い。本発表では、放射性セシウム（Cs-137）を用いた樹木ポプラ内のセシウム輸送とその日長による変化の観察、そしてその輸送を制御するPttSKOR-like2輸送体について紹介する。, 第18回放射線プロセスシンポジウム

Carbon-coated LiCoPO4 particles are synthesized by one-pot hydrothermal process using three different organic additives (carboxymethylcellulose sodium salt (CMC), glucose, and ascorbic acid). The effect of the organic additives on particle size, morphology, nature of carbon coating, and electrochemical property of the resulting LiCoPO4 is investigated. CMC plays important roles to decrease the particle size and form well-covered carbon coating on the surface. Carbon-coated LiCoPO4 prepared using CMC delivers higher initial discharge capacity of 135 mA h g−1 at 0.1 C, and shows superior rate capability and cyclic performance than the other samples. The improved electrochemical characteristics are attributed to not only the fine particle which allows facile electronic and ionic transport, but also the high coverage of carbon coating which improves the electrical conductivity and prevents the irreversible reactions of the charged LiCoPO4 with electrolyte.

In perennial woody plants, dormancy-induced alteration of potassium (K) localization is assumed one of the mechanisms for adapting and surviving the severe winter environment. To establish if radio-cesium (137Cs) localization is also affected by dormancy initiation, the artificial annual environmental cycle was applied to the model tree poplar. Under the short day-length condition, the amount of 137Cs in shoots absorbed through the roots was drastically suppressed, but the amount of 42K was unchanged. Potassium uptake from the rhizosphere is mainly mediated by KUP/HAK/KT and CNGC transporters. However, in poplar, these genes were constantly expressed under the short-day condition and there were no up- or down-regulation. These results indicated the suppression of 137Cs uptake was triggered by the short-day length, however, the key transporter and the mechanism remains unclear. We hypothesized that Cs and K transport systems are separately regulated in poplar.

Auxin flow is important for different root developmental processes such as root formation, emergence, elongation and gravitropism. However, the detailed information about the mechanisms regulating the auxin flow is less well understood in rice. We characterized the auxin transport-related mutants, Ospin-formed2-1 (Ospin2-1) and Ospin2-2, which exhibited curly root phenotypes and altered lateral root formation patterns in rice. The OsPIN2 gene encodes a member of the auxin efflux carrier proteins that possibly regulates the basipetal auxin flow from the root tip toward the root elongation zone. According to DR5-driven GUS expression, there is an asymmetric auxin distribution in the mutants that corresponded with the asymmetric cell elongation pattern in the mutant root tip. Auxin transport inhibitor, N-1-naphthylphthalamic acid and Ospin2-1 Osiaa13 double mutant rescued the curly root phenotype indicating that this phenotype results from a defect in proper auxin distribution. The typical curly root phenotype was not observed when Ospin2-1 was grown in distilled water as an alternative to tap water, although higher auxin levels were found at the root tip region of the mutant than that of the wild-type. Therefore, the lateral root formation zone in the mutant was shifted basipetally compared with the wild-type. These results reflect that an altered auxin flow in the root tip region is responsible for root elongation growth and lateral root formation patterns in rice.

Short day length-induced alteration of potassium (K) localization in perennial trees is believed to be a mechanism for surviving and adapting to severe winters. To investigate the relationship between cesium (Cs) and K localizations, a model tree poplar, hybrid aspen T89, was employed. Under short day length conditions, the amount of 137Cs absorbed through the root and translocated to the root was drastically reduced, but 42K was not. Potassium uptake from the rhizosphere is mediated mainly by KUP/HAK/KT and CNGC transporters. In poplar, however, these genes were constantly expressed under short-day conditions except for a slight increase in the expression a KUP/HAK/KT gene six weeks after the onset of the short-day treatment. These results indicated that the suppression of 137Cs uptake was triggered by short day length but not regulated by competitive Cs+ and K+ transport. We hypothesize that there are separately regulated Cs+ and K+ transport systems in poplar.

Small RNAs, such as small interfering RNAs (siRNAs) or microRNAs (miRNAs), regulate gene expression at transcriptional and posttranscriptional levels in eukaryotes. miRNAs are processed from duplexes formed on single-stranded RNA. They regulate expression of their target gene either by cleaving mRNA or supressing translation. In general, the primary miRNA transcripts are synthesized by RNA polymerase II and processed similarly to mRNAs. MIRNA genes are usually located in transcriptionally active euchromatic regions. In contrast, siRNAs are processed from duplexes made of two RNA molecules. One of them is often derived from a transposable element (TE) or from repetitive sequences that reside in heterochromatic regions. The other strand is synthesized by the RNA-dependent RNA polymerase on the first strand as a template. siRNAs establish epigenetic marks in parasitic DNA such as TEs, thus they usually act in cis. The rice miRNA miR820, encoded by CACTA TEs (five copies, located on different chromosomes), reduces the expression of the de novo DNA methyltransferase gene OsDRM2. Because miR820 is derived from silent TEs, in which the heterochromatic histone modifications are enriched, the mechanism of MIR820 transcription could be expected to differ from typical miRNAs. Here we show that the primary transcript of MIR820 is mainly derived from the CACTA TE copy on chromosome 7 (MIR820b). Histone modification and DNA methylation status around MIR820b differed from that of the other four loci. These unique epigenetic modifications in MIR820b were only found around the miR820 coding region. We conclude that MIR820b transcription may depend on the unique epigenetic modifications, which in turn may be established by the action of miR820 in cis. This suggests a dual function of miR820 in cis and in trans.

Natural variation for drought tolerance is a major issue in adaptation and geographic distribution of terrestrial plants. Despite the importance, little is known about the genes and molecular mechanisms that determine its naturally occurring diversity. We analyzed the intraspecific drought tolerance variation between 2 accessions of Arabidopsis thaliana, Columbia (Col)-0 and Wassilewskija (Ws)-2. Measurement of weight loss in detached seedlings demonstrated a clear difference between drought-tolerant Col-0 and drought-sensitive Ws-2. They also differed in their stomatal response under drought condition. Using a quantitative genetic approach, we found a significant quantitative locus on chromosome 1. Surveying in the locus, we extrapolated that the SLAC1 gene, which is associated with stomatal closure, was likely responsible for the difference of drought tolerance. Comparison of their nucleotide and amino acid sequences revealed that there were few differences in regions encoding SLAC1 protein but was a large deletion in SLAC1 promoter of Ws-2. Histochemical GUS staining showed that the SLAC1 expressed dominantly in guard cells of Col-0, but did less in guard cells of Ws-2. Quantitative PCR analysis also showed that transcript level of SLAC1 in guard cells was higher in Col-0 than in Ws-2. The SLAC1 transcription analyses indicate low accumulation of SLAC1 in guard cells of Ws-2. When taken together, our results suggest that the low drought tolerance of Ws-2 was associated with the deletion of the promoter region of Ws-2 SLAC1.

miR820 is a small RNA species (22 and 24 nucleotides), produced from transcripts originated from a region inside CACTA DNA transposons in rice. Because MIR820 is a transposon gene, its expression may depend on the transposon copy number. Here, we investigated the copy number of MIR820 and its expression levels in various cultivars and wild species of rice. We found no correlation between copy number and expression level, suggesting that MIR820 transcription is regulated not by the copy dosage but by the epigenetic state of each copy.

Leaf shape is one of the key determinants of plant architecture. Leaf shape also affects the amount of sunlight captured and influences photosynthetic efficiency; thus, it is an important agronomic trait in crop plants. Understanding the molecular mechanisms governing leaf shape is a central issue of plant developmental biology and agrobiotechnology. Here, we characterized the narrow-leaf phenotype of FL90, a linkage tester line of rice (Oryza sativa). Light and scanning electron microscopic analyses of FL90 leaves revealed defects in the development of marginal regions and a reduction in the number of longitudinal veins. The narrow-leaf phenotype of FL90 shows a two-factor recessive inheritance and is caused by the loss of function of two WUSCHEL-related homeobox genes, NAL2 and NAL3 (NAL2/3), which are duplicate genes orthologous to maize NS1 and NS2 and to Arabidopsis PRS. The overexpression of NAL2/3 in transgenic rice plants results in wider leaves containing increased numbers of veins, suggesting that NAL2/3 expression regulates leaf width. Thus, NAL2/3 can be used to modulate leaf shape and improve agronomic yield in crop plants.

Introduction LiCoPO4 has been focused as a promising cathode material to realize lithium-ion batteries with high energy density due to the high specific capacity of 167 mA h g-1 and a high operating potential of Co2+/Co3+ redox at 4.8 V vs. Li/Li+. However, the high operating potential sometimes results in a large irreversible capacity from the oxidative decomposition of electrolyte solutions during charge process. The decomposition occurs on the surface of electrode, so that coarse particles of active materials with low surface areas reduces the irreversible capacity. Based on this discussion, we synthesized the size-controlled LiCoPO4 and LiCoPO4 partially substituted with Fe and Ni by hydrothermal method1) . The particle sizes can be controlled by hydrothermal duration. The effect of particle size on the irreversible capacity derived from the oxidative decomposition of electrolyte solutions was investigated. Experimental LiCoPO4 was prepared from Li3PO4, CoSO4･7H2O. LiCo0.9M0.1PO4 (M=Fe or Fe) were prepared by replacing 10% of CoSO4･7H2O with FeSO4･7H2O or NiSO4･5H2O. Li3PO4, CoSO4･7H2O, FeSO4･7H2O (NiSO4･5H2O) were mixed in a molar rate of 1 : 0.9 : 0.1. The prepared solution was heated for 48 hours at 200 ºC with stirring in an autoclave. The product was collected by centrifugation and freeze-drying. Then, the resulting sample was mixed with sucrose and heated at 700 ºC for 1 h under 97 % Ar + 3% H2 atmosphere to form a carbon layer on the particle surface. The crystal structure, morphology, composition, and surface area of each sample were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma emission spectrometer (ICP) and the BET method, respectively. The state of carbon on the LiCo0.9M0.1PO4 particle was investigated by Raman spectroscopy. The carbon-coated samples were mixed with acetylene black and polyvinylidene fluoride in a weight ratio of 15% and 10% to make composite electrodes, The electrochemical properties were characterized with 2032 coin type cell in a potential range of 2.5 ~ 5.1 V at 30 ºC. Results and discussions Figure 1 shows XRD patterns of the products. All peaks were assigned to those of LiCoPO4 and no impurity was observed. In addition, the substitutions of Co in LiCoPO4 with Ni and Fe were confirmed from the peak shifts to higher and lower angles, respectively. Those substitutions were also confirmed by ICP analysis. The carbon-coating on the particle surface was confirmed by Raman spectroscopy for all samples after the heat treatment at 700 ºC with sucrose. The specific surface areas of samples were characterized by BET measurements to be 8.75 m2 g-1(LiCoPO4), 5.40 m2 g-1 (LiCo0.9Ni0.1PO4), 1.00 m2 g-1 (LiCo0.9Fe0.1PO4), respectively. The particle size was increased by the metal replacement. Figure 2 shows the cycleability of the cells for LiCoPO4, LiCo0.9Ni0.1PO4 and LiCo0.9Fe0.1PO4 cathodes. The initial discharge capacity of LiCo0.9Fe0.1PO4 / C represented the largest value of 148 mAh g-1. The irreversible capacity of LiCoPO4 in the initial cycle was about 196 mAh g-1. In contrast, LiCo0.9Ni0.1PO4 / C and LiCo0.9Fe0.1PO4 / C showed the smaller irreversible capacities of 112 mAh g-1 and 76 mAh g-1, respectively. This result suggests that the irreversible capacity of the metal substitution products in the initial cycle was less than that of no-metal substitution product. Figure 3 shows the SEM image of the LiCo0.9Fe0.1PO4 / C particle after the cycle test. No crack in the particle was observed. Thus, the deterioration of the discharge capacity may not be due to the deterioration of the particles. LiCo0.9M0.1PO4 particle size was increased by both longer hydrothermal treatment duration and metal-substitution. The BET surface area of particle was decreased to 1.00 m2 g-1 from 8.75 m2 g-1. The decomposition of the electrolytic solution during charge was reduced with decreasing of BET surface area corresponding to electrochemical surface area. The irreversible capacity in the initial cycle was decreased to 76 mAh g-1 from 196 mAh g-1. Furthermore, it has been reported that Fe-doping improves the Li conductivity and electronic conductivity of LiCoPO4 2). These improvements are also possible reasons. Reference 1) J. L. Allen, T. R. Jow, J. Wolfenstine, J Power sources, 196 (2011) 8656-8661. 2) Y. M. Kang, Energy Environ. Sci, 4 (2011) 4978-4983 Figure 1

Introduction Lithium ion batteries (LIB) have been widely used as power sources for portable electronic devices such as laptop computers and cellular phones due to their high energy density. A battery research has been become more important issue for large scale applications such as EVs and HEVs. LiMnPO4 has been focused as a promising cathode material to realize high performance of LIB. So far, many approaches have been done to improve the electrochemical properties of LiMnPO4 by carbon coating, cation doping and so on. An electric and Li+ conductivities of LiMnPO4 are intrinsically low. The Mn substitution with Fe has been done as one of effective approaches to improve the electrochemical properties of LiMnPO4. However, its substitution effect has not been fully understood. The conventional evaluation method using composite electrodes has some difficulties due to porous structure of composite electrode. Therefore, we have conducted a single particle measurement using one active material particle (mainly secondary particle) or a composite particle obtained by taking out a part of composite electrode. We have reported to reduce an influence of the electrode structure on the electrochemical response by using single particle measurement (1). A phosphate-based cathode materials have an excellent thermal stability. These materials are promising active materials for large batteries. However, a slow electrochemical reaction of LiMnPO4 should be improved to obtain high rate capability. A Fe substitution for LiMnPO4 has improved its rate capability (2). In this study, we synthesized carbon-coated LiFexMn1-xPO4. A single particle measurement was employed to understand the intrinsic effect of Mn substitution with Fe on the electrochemical properties of LiMnPO4. Experimental Li2SO4, MnSO4•5H2O, FeSO4•7H2O, (NH4)2HPO4, and carboxymethyl cellulose (CMC) were used as starting materials to synthesized carbon coated LiFexMn1-xPO4 by hydrothermal method. The hydrothermal treatment was performed at 200 ºC for 3 h. The reaction product was dried and then grounded with planetary ball mill (400 rpm, 1 hour × 10 times) to obtain fine powder. The obtained powder was then heated at 700 ºC for 1 h under 97% Ar + 3% H2 atmosphere for a graphitization of CMC on particle surface to obtain LiFex Mn1-xPO4/C. A small composite particle used for single particle measurement was obtained by stripping from the composite electrode with a weight ratio of LiFexMn1-xPO4/C: AB: PVdF = 85: 10: 5 on aluminum current collector. Au micro-electrode with 10 mm diameter was attached to a LiFexMn1-xPO4/C composite electrode particle in an electrolyte (1 mol dm-3 LiPF6 / EC : EMC = 3 : 7 in vol.) using a micromanipulator under optical microscope observation. All the experiments were carried out under Ar atmosphere to remove the effect of water and oxygen. Results and discussion Figure 1 shows the XRD patterns of LiFexMn1-xPO4 synthesized by hydrothermal method. All peaks are attributable to olivine structure of LiFexMn1-xPO4, suggesting that the synthesized LiFexMn1-xPO4 samples are single phase without impurity. The Fe substitution in LiMnPO4was also confirmed from Rietveld analysis. Figure 2 shows the rate capabilities of LiFexMn1-xPO4/C composite electrode particles by single particle measurement. Discharge capacities at 1.5 C and 15 C were plotted against x in LiFexMn1-xPO4/C. In single particle measurement, in order to normalize a variation of particle size, the capacities were indicated by depth of discharge (DOD). The capacity retention at 15 C was improved with increasing amount of Fe substitution. A comparison of discharge curves for each composite particle, a potential plateau corresponding to Mn2+/3+ appeared at more noble potential with increasing of Fe substitution amount. The improvement of rate capability may be due to the improved electronic conductivity and suppressed Jahn-Teller deformation of Mn by Fe substitution. Reference [1] H. Munakata, K. Annaka, K. Kanamura, The 81th Electrochemical Society of Japan, p.343(2Q01). [2] Seung-Min Oh et al , J. Power Sources 196 (2011) 6924-6928 Figure 1

Lithium metal phosphates (LiMPO4) have attracted much attention as promising cathode materials to realize high safety in rechargeable lithium-ion batteries. Their thermal and structural stabilities are very high due to strong covalent bonds among oxygen and phosphorus atoms compared to those of currently used LiCoO2. Actually, the good cycle performance of LiFePO4 has been demonstrated in many practical applications [1]. However, its operating potential (around 3.5 V vs. Li /Li+) is lower than that of LiCoO2. Thus, it is difficult to improve the energy density of lithium-ion batteries by replacing LiCoO2 with LiFePO4. In addition to LiFePO4, LiCoPO4 has become of major interest lately due to a high operating potential at around 4.8 V vs. Li /Li+. The ionic and electronic conductivities of lithium metal phosphates are basically very low, and transition metal-doping has been studied as one of effective approaches for their improvement [2, 3]. In this study, we synthesized transition metal-doped LiCoPO4 (LiCo0.9 M 0.1PO4 (M= Co, Fe, Mg)) by hydrothermal method and investigated those electrochemical properties thoroughly. Li3PO4, CoSO4·7H2O and FeSO4·7H2O or MgSO4·7H2O as starting materials were mixed in molar ratio of 1: 0.9: 0.1. This mixture and carboxymethyl cellulose sodium salt (carbon coating) were added to degassed water under N2 atmosphere to obtain the precursor solution with Co2+ and M ions concentration = 3 mol dm-3. After hydrothermal treatment at 200 ºC for 24 h, the resulting precipitation was separated centrifugally and then freeze-dried. The obtained powder was then heated at 700 ºC for 1 h under 97% Ar + 3% H2 atmosphere to promote the graphitization of carbon species on particle surface to obtain LiCo0.9 M 0.1PO4/C. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TGA) and Raman spectroscopy, respectively. The electrochemical properties of sample were investigated using a composite electrode with the weight composition of LiCo0.9 M 0.1PO4/C: acetylene black: polyvinylidene difluoride = 75: 15: 10 in 2032 coin type cells. 1 mol dm-3 LiPF6/ ethylene carbonate: diethyl carbonate = 1: 2 (in volume) was used as an electrolyte solution. The charge - discharge measurement was performed in a potential range of 2.5 ~ 5.1 V at 30 ºC. Fig. 1 shows XRD patterns of LiCoPO4/C, LiCo0.9Fe0.1PO4/C and LiCo0.9Mg0.1PO4/C. Each sample was well-crystallized in an orthorhombic olivine structure with a Pnma space group. The XRD peaks of LiCoPO4/C shifted to larger and smaller 2θ in LiCo0.9Fe0.1PO4/C and LiCo0.9Mg0.1PO4/C, respectively. This result agrees with different ion sizes of Fe2+ (larger) and Mg2+ (smaller) compared to Co2+, and suggests that Co2+ ions in the LiCoPO4 are successfully substituted in the doped LiCo0.9 M 0.1PO4. Fig. 2 shows SEM images of LiCoPO4 with and without M-doping. The size of particles became a little bit larger by Fe-doping. In contrast, very small particles were obtained by Mg-doping. Fig. 3 shows the charge - discharge curves of the samples at initial 3 cycles. The polarization became lower in both doped samples than that of pristine LiCoPO4/C. In addition, the irreversible capacity between charge and discharge capacities decreased by doping of Fe2+ and Mg2+ions. References [1] A. K. Padhi, K. S. Nanjundaswamy, J. B. Goodenough, J. Electrochem. Soc., 144(1997) 1188-1194. [2] L. Dimesso, C. Spanheimer, W. jaegermann, J Power sources, 254(2014) 204-208. [3] J. L. Allen, T. R. Jow, J. Wolfenstine, J Power sources, 196 (2011) 8656-8661. Figure 1

Active materials for rechargeable lithium-ion batteries are generally evaluated as porous composite electrodes including binder and conductive carbon. However, this method sometimes makes it difficult to understand the intrinsic electrochemical properties of active material because the electrochemical response of composite electrode is strongly influenced by the electrode structure and composition. In order to overcome this problem, we have focused on single particle measurement, in which a single particle of active material can be evaluated [1]. Lithium metal phosphates have been investigated as promising cathode active materials with high thermal and structural stability. Though their electronic and Li+ ion conductivities are very low, those drawbacks can be improved by carbon coating and formation of fine particles, respectively. It has been demonstrated that the electrochemical performance of LiFePO4 can be increased up to a practical use level by such particle design. However, its operating potential is low (around 3.5 V vs. Li /Li+) compared to conventional LiCoO2. Thus, LiCoPO4 have been particularly focused in recent years, due to its high operating potential (around 4.8 V vs. Li /Li+). In this study, the effect of carbon coating on the electrochemical properties of LiCoPO4 was investigated by single particle measurement. LiCoPO4 was synthesized by hydrothermal method using Li3PO4 as Li and P sources and CoSO4·7H2O as a Co source, then coated with carbon by using sucrose as a carbon source. The morphology of LiCoPO4­ particles was characterized with a scanning electron microscope (SEM). The amount of carbon on LiCoPO4 was estimated by thermogravimetric analysis (TGA). The electrochemical properties of pristine and carbon-coated LiCoPO4 particles were evaluated by single particle measurement (Fig. 1), using a grass coated Au wire (Φ10 μm diameter) as a micro current collector. The single particle measurement was performed in a potential range of 2.5 ~ 5.1 V vs. Li /Li+ at room temperature under Ar atmosphere. A mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (3:7 in volume) containing 1 mol dm-3 LiPF6 was used as an electrolyte solution. Fig. 2 shows SEM images of pristine and carbon-coated LiCoPO4. The pristine LiCoPO4 particles were cubic and more than 5 μm in size, and those shape and size were maintained after the carbon coating. From TGA result, the amount of carbon on LiCoPO4 was estimated to be 0.5 wt%. Fig. 3 shows the charge – discharge curves of pristine LiCoPO4 particle at initial 3 cycles, in which the charge was carried out at 0.2 nA until the electrode potential reached to 5.1 V vs. Li /Li+ and then the potential was hold at 2 hours, followed by 0.2 nA discharge. It was hardly operated due to high ohmic resistance. Fig. 4 shows the charge – discharge curves of carbon-coated LiCoPO4 particle with 20 μm diameter at initial 3 cycles, in which the charge was carried out at 3 nA until the electrode potential reached to 5.1 V vs. Li /Li+ and then the potential was hold until the charge current dropped to 0.3 nA, followed by 3 nA discharge. The carbon-coated LiCoPO4 showed better electrochemical performance with the plateaus corresponding to Li+ extraction and insertion were clearly observed at 4.8 and 4.7 V vs. Li /Li+, respectively, although the irreversible capacity and capacity fading were observed due to the decomposition of electrolyte solution at high voltage [2]. Electrochemical properties of LiCoPO4 was greatly improved by the small amount of carbon even though the particle size was as large as 20 μm, suggesting that LiCoPO4 is a promising cathode material to realize high energy density lithium-ion batteries. References [1] H. Munakata et al. , Journal of Power Sources 217 (2012) 444 – 448. [2] E. Markevich et al. , Electrochemistry Communications 15 (2012) 22–25. Figure 1