JPS58128658A - Silver oxide secondary battery - Google Patents

Abstract

PURPOSE:To enhance the charge-and-discharge reversibility of a silver oxide secondary battery by increasing the amount of electrolyte held in the positive electrode by mixing a specified amount of potassium titanate fiber into a positive active material. CONSTITUTION:After 5-50wt% of potassium titanate fiber which is a minute monocrystal fiber of potassium titanate is mixed into silver oxide, the mixture is pressed and molded so as to form a positive active material 1. Next, after the positive active material 1 is installed in a positive can 3, a separator 4, an electrolyte-absorbing member 5 and a negative agent 7 are combined, and an electrolyte prepared by dissolving zinc oxide into an aqueous potassium hydroxide solution is poured into the battery, thereby constituting a silver oxide secondary battery. Therefore, due to the liquid-absorbing performance of the potassium titanate fiber, the amount of the electrolyte held in the positive electrode can be increased. As a result, the charge-and-discharge reversibility of the battery can be enhanced by reducing the concentration of Ag ions during the discharge according to the above increase of the amount of the electrolyte held in the positive electrode.

Description

【発明の詳細な説明】 本発明は酸化銀二次電池の改良に係り、充放電可逆性の
向上をはかることを目的とする。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of a silver oxide secondary battery, and aims to improve charge/discharge reversibility.

酸化銀二次電池の充放電特性は特に深い深度の場合必ず
しも満足できるものとはいえない。これは充電時に生成
するＡｇｚＯＩ−がある厚みになるとＯトイオンの拡散
が困難となり、充電反応が進行しにくくなることと、放
電で生成する銀粒子が徐々に大きくなっていくために反
応面積が減少し充電特性が低下していくことによるもの
と考えられる。The charging and discharging characteristics of silver oxide secondary batteries are not necessarily satisfactory, especially at deep depths. This is because when the AgzOI produced during charging reaches a certain thickness, it becomes difficult for the oxygen ions to diffuse, making it difficult for the charging reaction to proceed, and because the silver particles produced during discharging gradually become larger, the reaction area decreases. This is thought to be due to the deterioration of charging characteristics.

本発明はそのような事情に照らし、チタン酸カリウム繊
維を正極活物質中に混入することにより、正極内の″電
解液保持量を増加させ、充放電可逆性を向上させたもの
である。In light of such circumstances, the present invention increases the amount of electrolyte held in the positive electrode and improves charge/discharge reversibility by incorporating potassium titanate fibers into the positive electrode active material.

本発明において用いるチタン酸カリウム繊維はチタン酸
カリウムのウィスカー（微細な単結晶繊維）であって、
耐酸化性、耐アルカリ性にすぐれ、吸液性を有している
。従って、これを正極活物質に添加し、混合すると正極
内の電解液保持量が増加し、電解液量が多くなったぶん
だけ放電時のＡｐ　＋イオンの濃度が低下して、析出す
る銀粒子が微細になり、充電時の反応面積が増加して充
電電気量が多くなり、充放電可逆性が向上する。The potassium titanate fibers used in the present invention are potassium titanate whiskers (fine single crystal fibers),
It has excellent oxidation resistance, alkali resistance, and liquid absorption properties. Therefore, when this is added to the cathode active material and mixed, the amount of electrolyte held in the cathode increases, and the concentration of Ap + ions during discharge decreases by the amount of electrolyte that increases, reducing the amount of silver particles that precipitate. It becomes finer, increases the reaction area during charging, increases the amount of charged electricity, and improves charge/discharge reversibility.

チタン酸カリウム繊維の添加量としては、少なすぎると
上述の効果を充分に発揮で春ないし、多すぎるとそのぶ
ん正極活物質の充填量が減少して放電容量の低下を招く
ので、正極活物質との混合物中チタン酸カリウム繊維が
５〜５０重ｔ％になるようにするのが好ましい。なお、
これら正極活物質とチタン酸カリウム繊維との混合物に
導電性、流動性などの改良のためりん状黒鉛などの導電
助剤を少量添加してもよい。If the amount of potassium titanate fiber added is too small, the above-mentioned effect will not be fully exhibited, and if it is too large, the filling amount of the positive electrode active material will decrease and the discharge capacity will decrease. It is preferable that the potassium titanate fibers in the mixture be 5 to 50% by weight. In addition,
A small amount of a conductive additive such as phosphorous graphite may be added to the mixture of these positive electrode active materials and potassium titanate fibers to improve conductivity, fluidity, etc.

つぎに本発明の実施例を図面とともに説明する。Next, embodiments of the present invention will be described with reference to the drawings.

第１図は本発明の酸化銀二次電池の一実施例を示す断面
図であり、（１）は正極合剤で、この正極合剤（１）は
酸イト銀（Ａｇ２０）　１００部（重量部、以下同様）
とチタン酸カリウム繊維（イＬ学組成に２０・６Ｔｉ０
２、平均繊維長２５５ｍ、平均繊維径０．２μＦｆｆ）
１０部とを混合した混合物２２０ｍＦを採取して５　ｔ
／ａｇ２で加圧成形したものである。（２）は正極合剤
の加圧成形時に正極合剤（１）の同縁部に固着させたス
テンレス鋼製環状台座であり、（３）は正極缶、（４）
はセパレータで、このセパレータ（４）はセロハンの両
面にグラフトフィルム（架橋低密度ポリエチレンフィル
ムにメタクリル酸をグラフト重合させたグラフトフィル
ム）をラミネートした複合膜からなるものである。（５
）はビニロン−レーヨン混抄紙よりなる電解液吸収体で
、（６）は負極熾子板であり、（７）は６４　ｍｇのア
マルガム化亜鉛を活物質とする負極剤で、（８）　Ｆｉ
ナイロンｌｌ製の環状ガスケットである。そして、この
電池には酸化亜鉛を溶解させた８５電量チ水酸イヒカリ
ウム水溶液よりなる電解液が注入されている。FIG. 1 is a cross-sectional view showing one embodiment of the silver oxide secondary battery of the present invention. (1) is a positive electrode mixture, and this positive electrode mixture (1) contains 100 parts (parts by weight) of silver oxide (Ag20). , hereinafter the same)
and potassium titanate fiber (20.6 Ti0 in the chemical composition)
2. Average fiber length 255m, average fiber diameter 0.2μFff)
Collect 220 mF of the mixture of 10 parts and add 5 t.
/ag2 pressure molded. (2) is a stainless steel annular pedestal fixed to the same edge of positive electrode mixture (1) during pressure molding of the positive electrode mixture, (3) is a positive electrode can, and (4)
is a separator, and this separator (4) is made of a composite film in which a graft film (a graft film obtained by graft polymerizing methacrylic acid to a cross-linked low-density polyethylene film) is laminated on both sides of cellophane. (5
) is an electrolyte absorber made of vinylon-rayon mixed paper, (6) is a negative electrode glass plate, (7) is a negative electrode material containing 64 mg of amalgamated zinc as an active material, and (8) Fi
It is an annular gasket made of nylon II. An electrolytic solution consisting of an 85-coulometric potassium thihydroxide aqueous solution in which zinc oxide is dissolved is injected into this battery.

つぎの第１表は前記のごとき構成からなる本発明の′醒
池＾とチタン酸カリウム繊維を加えることなく酸化銀の
み２５０　Ｆｊｆｆを加圧成形した正極を用いた従来電
池Ｂ　ｆ　１５　ｋΩ定抵抗放電で１．２ｖまで放電し
、１　ｍＡ定電流充電で１．８Ｖまで充電したときの容
量回復率を示すものである。なお容量回復率は１５にΩ
定抵抗放電で１．２■まで放電したときの放電電気量を
Ｑｌ、１　ｍＡ定電流充電で１．８ｖまで充電したとき
の充電電気量をＱ２とするとき、下記の第１式％式％ 第１表に示すように、本発明の電池Ａ＃ｉ従来電池Ｂに
比べて容量回復率が大きく、充放電可逆性がすぐれてい
゛る。The following Table 1 shows the conventional battery B f 15 kΩ constant resistance using the 'same pond' of the present invention having the above-mentioned configuration and a positive electrode formed by pressure molding only silver oxide without adding potassium titanate fiber. It shows the capacity recovery rate when the battery was discharged to 1.2V and charged to 1.8V with 1 mA constant current charging. The capacity recovery rate is 15Ω.
When the amount of electricity discharged when discharging to 1.2V with constant resistance discharge is Ql, and the amount of electricity charged when charging up to 1.8V with 1 mA constant current charging is Q2, the following formula 1% formula % As shown in Table 1, the battery A#i of the present invention has a larger capacity recovery rate and better charge/discharge reversibility than the conventional battery B.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の酸化銀二次′１１池の一実施例を小−
＃ｌ！ｌ′Ｉｒ！ｌ］凶Ｃ：　ｈ　６　。 （１）・・・正極合剤 特許出願人　　日立マクセル株式会社 第１図Figure 1 shows a small example of the secondary silver oxide '11 pond of the present invention.
#l! l'Ir! l] Bad C: h 6. (1)...Cathode mixture patent applicant Hitachi Maxell Ltd. Figure 1

Claims (1)

【特許請求の範囲】[Claims] ！、　チタン酸カリウム繊維を正極活物質中和混入し九
ことを特徴とする酸化銀二次電池。! A silver oxide secondary battery characterized in that potassium titanate fibers are neutralized and mixed with a positive electrode active material.