Structural Studies in Lithium Insertion into SnO-B[sub 2]O[sub 3] Glasses and Their Applications for All-Solid-State Batteries

Abstract

The local structure of electrochemically lithium-inserted SnO-B 2 O 3 glasses was investigated by several spectroscopic techniques to clarify a lithium insertion mechanism into the glasses. 50SnO•50B 2 O 3 ͑mol %͒ glass showed two plateaus around 1.5 and 0.5 V ͑vs. Li ϩ /Li͒ on the lithium insertion process and exhibited a high capacity of 1240 mAh g Ϫ1 in the case of using a conventional liquid electrolyte. On the first plateau ͑1.5 V vs. Li ϩ /Li͒, metallic Sn with small domains was formed and the coordination environment at boron in the glass network was not changed. On the second plateau ͑0.5 V vs. Li ϩ /Li͒, the borate glass network was rearranged by a transformation from tetrahedral BO 4 to trianglar BO 3 boron units, which provides an additional free space compensating an increase in volume followed by a formation of Li-Sn alloy domains. Hence, the larger the fraction of tetrahedral BO 4 unit is in the SnO-B 2 O 3 glasses, the higher the charge-discharge capacities are. The SnO-B 2 O 3 glasses are applicable to all-solid-state lithium rechargeable batteries as anode materials with high capacity.Tin oxide-based glasses and crystals have been studied extensively as anode materials for lithium secondary batteries since the first report by Idota et al. [1][2][3][4][5][6][7][8][9] These anode materials show high specific capacities twice that of carbon materials, which are commercially used as anode materials for lithium-ion secondary batteries.Recently, we reported that the binary system SnO-B 2 O 3 has a wide glass-forming region with 0 р SnO ͑mol %͒ р 75, and these glasses work as an anode material with high capacity using a conventional cell with liquid electrolytes. 10 Charge-discharge capacities depend on the glass composition and are maximized at the composition of 50 mol % SnO. 11 B NMR measurements have revealed that four-coordinated boron in the glass network is maximized at the composition of 50 mol % SnO, 11 suggesting that there is a close relationship between electrochemical capacity and local glass structure.To clarify the origin of the relationship, an investigation of structural changes during electrochemical lithium insertion to the SnO-B 2 O 3 binary glasses is important. Structural studies on electrochemical reaction of lithium with SnO-based glasses by several spectroscopic techniques have been reported for multi-oxide systems such as SnO-B 2 O 3 -P 2 O 5 -Al 2 O 3 . 5,6,8 Those studies for the simple binary system SnO-B 2 O 3 , however, have not been examined in detail.Nowadays, developing all-solid-state lithium rechargeable batteries with high reliability and high safety is desirable to replace the current lithium-ion batteries using liquid electrolytes, which have inherently irresolvable problems of leakage and inflammability. Allsolid-state electrochemical cells consisting of Li-In alloy or In ͑an-ode͒, a superionic oxysulfide glass ͑solid electrolyte͒, and LiCoO 2 ͑cathode͒ have been reported to work as lithium secondary batteries and exhibit excellent cycling properties. 12-15 SnO-ba...

Preparation and characterization of SnO–P2O5 glasses as anode materials for lithium secondary batteries

“…4. Two-step electrochemical reaction was also observed in the SnO-B 2 O 3 and SnO-BPO 4 systems [2][3][4][5][6][7]11]. The first plateau is due to the formation of metallic Sn 0 (Sn 2+ !…”

“…We have analyzed the structure of the SnO-B 2 O 3 glasses by several spectroscopic techniques such as Raman, NMR, and XPS [9]. Glass transition temperatures, activation energies for viscous flow, and specific capacity of the glasses proved to be influenced by the glass structure, namely by four-coordinated borons and non-bridging oxygens in the glass network [9][10][11]. From the structural point of view, binary phosphate glasses are an interesting glass matrix as the SnO-based anode materials for lithium secondary batteries.…”

Preparation and Characterization of Glassy Materials for All-Solid-State Lithium Secondary Batteries(Review)

“…Figure 10 shows the composition dependence of the first discharge capacity of the SnO-B 2 O 3 glasses using a mixture of 1 M LiPF 6 EC DEC 11 as a liquid electrolyte. 40 The fraction of four-coordinated boron N 4 in the glasses, which was determined by 11 B MAS-NMR measurements, 37 is also shown in this figure. The capacity increases up to the composition with 50 mol!…”

“…Figure 11 shows the first charge-discharge profile for anéall-ceramicêcell using the 50SnO50B 2 O 3 glass as a negative electrode and LiCoO 2 as a positive electrode. 40 The 95 0.6Li 2 S0.4SiS 2 5Li 3 BO 3 mol! oxysulfide glass was used as a solid electrolyte.…”

Tin-phosphate glass anode for sodium ion batteries

“…12 After their report, numerous studies on tin-based oxide glasses have been performed. [13][14][15][16][17][18][19][20] We developed the new tin-phosphate (designate as GSPO) glass anode recently. 11 It was shown from the XPS analysis that the average oxidation state of tin ions in GSPO is +2 in the region above 70 mol.% of SnO.…”