Ikuro Nakane

Lithium-containing manganese dioxide (composite dimensional manganese oxide: CDMO) as positive material for a lithium secondary battery

Abstract Lithium-containing manganese dioxide (CDMO) has been developed as the positive material for lithium secondary batteries. CDMO is prepared from lithium salt and manganese dioxide by heat treatment. It is a composite oxide of γ/β-MnO 2 and Li 2 MnO 3 . The influence on rechargeability of lithium salts, heat-treatment temperature, and manganese dioxide type has been investigated by conducting cycle tests with flat cells. Lithium hydroxide is more reactive with MnO 2 in the production of Li 2 MnO 3 than either Li 2 O or Li 2 CO 3 . The optimum condition for preparing CDMO is to heat treat LiOH and MnO 2 at about 375 °C. CDMO prepared from EMD (electrolytic manganese dioxide) yields a larger and more stable capacity than CDMO prepared from CMD (chemical manganese dioxide). Sodium-free EMD exhibits the largest discharge capacity.

Improvement of lithium-containing manganese dioxide (composite dimensional manganese oxide: CDMO) as positive material for lithium secondary batteries

Abstract Lithium-containing manganese dioxide (CDMO) has been developed as the positive material for lithium secondary batteries. CDMO is prepared from lithium salt and manganese dioxide by heat treatment. The material is a composite oxide of γ/β-MnO2 and Li2MnO3. The charge condition has been investigated in order to develop an improved CDMO that will exhibit a higher discharge voltage and a larger capacity. CDMO charged to a high potential (i.e., 3.6 V versus LiAl electrode) displays higher discharge voltage and larger capacity than CDMO subjected to normal charge (i.e., 3.3 V versus LiAl). It is concluded that when CDMO is charged to a high potential, lithium inserted not only by electrochemical reaction but also by heat treatment are removed from the γ/β-MnO2 phase. The optimum conditions for preparing improved CDMO is to heat treat LiOH and electrolytic manganese dioxide (EMD) at a Li/Li+Mn atomic ratio of 0.3 at ∼250 °C. The improved CDMO delivers a discharge capacity of over 200 mA h g−1. Also, excellent rechargeability is experienced, even when CDMO is charged to a high potential.

Investigation of an electrolyte for lithium secondary batteries with lithium-containing manganese dioxide as the positive material

Abstract We have already developed lithium-containing manganese dioxide (CDMO, composite dimensional manganese oxide) with excellent rechargeability and high discharge capacity for use as a positive electrode material in lithium secondary batteries. We also have improved the cycle performance of lithium-aluminum alloy for use as a negative electrode material by adding manganese to aluminum. The effect of an electrolyte on battery performance such as cycle life, discharge characteristics at low temperature and storage characteristics, were investigated for CDMO/Li-Al flat cells. LiCF 3 SO 3 showed excellent discharge characteristics both at room temperature and −20 °C. In addition, the charge/discharge cycle at room temperature was best when using LiCF 3 SO 3 -ethylene carbonate (EC)/1,2-butylene carbonate (BC)/1,2-dimethoxyethane (DME), as electrolyte.

A study on electrolytes for manganese dioxide-lithium cells

Abstract The physical properties of organic electrolyte used in manganese dioxide-lithium cells play a major role in determining various cell characteristics. The influence on various cell characteristics of electrolytes has been investigated with flat cells. LiCF 3 SO 3 is the suitable solute in terms of low-temperature, storage and overdischarge characteristics. Mixture of ethylene carbonate (EC), 1,2-butylene carbonate (BC) and 1,2-dimethoxyethane (DME) is the suitable solvent in terms of high-rate discharge and storage characteristics.